METHOD AND DEVICE FOR DETECTING THE PRESENCE OF A SINGLE TARGET NUCLEIC ACID IN A SAMPLE

1 . A method for detecting whether at least one molecule of a first target nucleic acid is present in a first sample portion, said method comprising:

loading a first sample portion into a first sample chamber, said first sample chamber comprising at least a portion of an inside of a first microcapillary device, said first sample portion comprising at least part of a sample, whereby if said first sample portion contains at least a single molecule of said target nucleic acid, said first sample portion would attain a detectable concentration of said target nucleic acid within a portion of said first sample portion after a single round of amplification;

subjecting said first sample portion in said first sample chamber to at least a first amplification step; and then

determining whether said first sample portion contains at least one molecule of said target nucleic acid.

2 . A method as recited in claim 1 , wherein said microcapillary device comprises at least one surface which exhibits at least one characteristic selected from the group consisting of hydrophobicity, hydrophilicity, electromagnetic force exertion and electrostatic force exertion.

3 . A method as recited in claim 1 , wherein said microcapillary device is tubular or linear.

4 . A method as recited in claim 1 , wherein said microcapillary device comprises a planar capillary region.

5 . A method as recited in claim 4 , wherein said sample chamber has opposing barriers separated by 500 microns or less, said barriers defining said capillary region.

6 . A method as recited in claim 5 , wherein said opposing barriers are separated by 100 microns or less.

7 . A method as recited in claim 1 , wherein said sample chamber has at least one dimension of 500 microns or less.

8 . A method as recited in claim 7 , wherein said sample chamber has at least one dimension of 100 microns or less.

9 . A method as recited in claim 1 , wherein said sample chamber has opposing barriers separated by 500 microns or less.

10 . A method as recited in claim 9 , wherein said sample chamber has opposing barriers separated by 100 microns or less.

11 . A method as recited in claim 1 , wherein said first microcapillary device is positioned in a microfluidic device which comprises a plurality of microcapillary devices, and said method further comprises loading a second sample portion into a second microcapillary device.

12 . A method as recited in claim 11 , wherein said method further comprises positioning at least a first amplification targeting reagent in said first sample chamber and positioning at least a second amplification targeting reagent in said second microcapillary device.

13 . A method as recited in claim 12 , wherein said first amplification targeting reagent differs from said second amplification targeting reagent.

14 . A method as recited in claim 1 , wherein said first amplification step is a homogeneous amplification step.

15 . A method as recited in claim 1 , wherein said first amplification step is a thermocycle step

16 . A method as recited in claim 1 , wherein if said first sample portion contains at least a single molecule of said target nucleic acid, said first sample portion would attain a detectable concentration of said target nucleic acid within a portion of said first sample chamber after a single amplification step.

17 . A method as recited in claim 1 , wherein said first sample chamber further comprises constituents for enabling amplification of a target nucleic acid.

18 . A method as recited in claim 1 , wherein said sample chamber comprises means for minimizing diffusion of said first sample portion.

19 . A method as recited in claim 18 , wherein said means for minimizing diffusion comprises at least one feature selected from among glass beads, gels, absorbent particles and electrophoretic means.

20 . A method as recited in claim 1 , wherein said method further comprises loading a first fluid and a second fluid into said first microcapillary device such that said first sample portion is disposed between said first fluid and said second fluid.

21 . A method as recited in claim 20 , wherein said first fluid is immiscible with said first sample portion, and said second fluid is immiscible with said first sample portion.

22 . A method as recited in claim 20 , wherein said method further comprises curing said first fluid and said second fluid.

23 . A method as recited in claim 20 , wherein said first fluid and said second fluid each comprise a first composition.

24 . A method as recited in claim 20 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

25 . A method as recited in claim 1 , wherein said method comprises loading a plurality of sample portions and a plurality of fluids into said first microcapillary device, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

26 . A method as recited in claim 1 , wherein said first sample chamber has an internal volume of about 100 nanoliters or less.

27 . A method as recited in claim 1 , wherein said first sample chamber has an internal volume of about 10 nanoliters or less.

28 . A method as recited in claim 1 , wherein said first sample chamber has an internal volume of about 1 nanoliter or less.

29 . A method as recited in claim 1 , wherein said first sample portion has a volume of about 60 nanoliters or less.

30 . A method as recited in claim 1 , wherein said first sample portion has a volume of about 100 nanoliters or less.

31 . A method as recited in claim 1 , wherein said first microcapillary device has an inner diameter in the range of from 20 micrometers to 75 micrometers.

32 . A method as recited in claim 1 , wherein said first microcapillary device has an inner diameter of about 100 micrometers.

33 . A method as recited in claim 1 , wherein said first microcapillary device has an inner diameter of about 100 micrometers or less.

34 . A method as recited in claim 1 , wherein said first microcapillary device has an inner diameter of about 500 micrometers or less.

35 . A method as recited in claim 1 , wherein said microcapillary device has at least one inner dimension of 20 micrometers or less.

36 . A method as recited in claim 1 , wherein said first microcapillary device has a length in the range of from about 1 mm to about 100 mm.

37 . A method as recited in claim 1 , wherein said first microcapillary device has a length of about 4 cm.

38 . A method as recited in claim 1 , wherein said first microcapillary device comprises at least two surfaces spaced from each other by about 20 micrometers or less.

39 . A method as recited in claim 1 , wherein said method further comprises positioning at least a first amplification targeting reagent in said first sample chamber.

40 . A method as recited in claim 39 , wherein said first amplification targeting reagent is positioned in said first sample chamber prior to said loading a first sample portion.

41 . A method as recited in claim 39 , wherein said first amplification targeting reagent is positioned in said first sample chamber while said first sample portion is being loaded into said first sample chamber.

42 . A method as recited in claim 39 , wherein said first amplification targeting reagent is positioned in said first sample chamber after said loading a first sample portion.

43 . A method as recited in claim 1 , wherein said loading of said first sample portion is carried out using at least capillary action.

44 . A method as recited in claim 1 , wherein said method further comprises positioning a sealing device adjacent to said first sample chamber.

45 . A method as recited in claim 44 , wherein said sealing device is selected from the group consisting of microscope slide coverslips, tapes, films, silicon films, silicon devices, and devices comprising an array of reactants.

46 . A method as recited in claim 1 , wherein said first target nucleic acid comprises at least one nucleic acid sequence of at least one pathogenic organism.

47 . A method as recited in claim 1 , wherein said first sample portion comprises at least one forensic sample.

48 . A method as recited in claim 1 , wherein said first target nucleic acid is indicative of the likelihood or presence of at least one genetic disorder.

49 . A method as recited in claim 1 , wherein said method for detecting whether at least one molecule of said first target nucleic acid is present in said first sample portion is part of a procedure selected from among the group consisting of analyzing mutations in activated oncogenes, molecular cloning, analyzing DNA, and detecting at least one sequence difference.

50 . A method as recited in claim 49 , wherein said procedure comprises at least one task selected from among the group consisting of generating specific sequences of DNA for cloning or use as probes, detecting segments of DNA for genetic mapping, detecting expressed sequences by amplification of particular segments of cDNA, analyzing expressed sequences by amplification of particular segments of cDNA, generating libraries of cDNA from small amounts of mRNA, generating large amounts of DNA for sequencing, analyzing mutations, and chromosome crawling.

51 . A method as recited in claim 49 , wherein said sequence difference is selected from among insertions, deletions and changes.

52 . A method as recited in claim 1 , wherein said method for detecting whether at least one molecule of said first target nucleic acid is present in said first sample portion is part of a procedure selected from among the group consisting of fertility procedures, immunology procedures, cytology procedures, gas analysis procedures and pharmaceutical screening procedures.

53 . A microfluidic device comprising:

a first sample chamber; and

a first sample portion, said first sample chamber comprising at least a portion of an inside of a first microcapillary device, said first sample portion being positioned in said first sample chamber, whereby if said first sample portion contains at least a single molecule of a target nucleic acid, said first sample portion would attain a detectable concentration of said target nucleic acid within a portion of said first sample chamber after a single round of amplification.

54 . A microfluidic device as recited in claim 53 , wherein said first sample chamber further comprises constituents for enabling amplification of a target nucleic acid.

55 . A microfluidic device as recited in claim 53 , wherein if said first sample portion contains at least a single molecule of said target nucleic acid, said first sample portion would attain a detectable concentration of said target nucleic acid within a portion of said first sample chamber after a single amplification step.

56 . A microfluidic device as recited in claim 55 , wherein said microcapillary device comprises a planar capillary region.

57 . A microfluidic device as recited in claim 56 , wherein said first sample chamber has opposing barriers separated by 500 microns or less, said barriers defining said capillary region.

58 . A microfluidic device as recited in claim 57 , wherein said opposing barriers are separated by 100 microns or less.

59 . A microfluidic device as recited in claim 53 , wherein said first sample chamber has at least one dimension of 500 microns or less.

60 . A microfluidic device as recited in claim 59 , wherein said first sample chamber has at least one dimension of 100 microns or less.

61 . A microfluidic device as recited in claim 53 , wherein said first sample chamber has opposing barriers separated by 500 microns or less.

62 . A microfluidic device as recited in claim 61 , wherein said first sample chamber has opposing barriers separated by 100 microns or less.

63 . A microfluidic device as recited in claim 53 , wherein said first microcapillary device has an inner diameter in the range of from 20 micrometers to 75 micrometers.

64 . A microfluidic device as recited in claim 53 , wherein said first microcapillary device has an inner diameter of about 100 micrometers.

65 . A microfluidic device as recited in claim 53 , wherein said first microcapillary device has an inner diameter of about 100 micrometers or less.

66 . A microfluidic device as recited in claim 53 , wherein said first microcapillary device has an inner diameter of about 500 micrometers or less.

67 . A microfluidic device as recited in claim 53 , wherein said first microcapillary device has a length in the range of from about 1 mm to about 100 mm.

68 . A microfluidic device as recited in claim 53 , wherein said first microcapillary device has a length of about 4 cm.

69 . A microfluidic device as recited in claim 53 , wherein said first microcapillary device comprises at least two surfaces spaced from each other by about 20 micrometers or less.

70 . A microfluidic device as recited in claim 53 , wherein said microfluidic device further comprises at least a first amplification targeting reagent positioned in said first sample chamber.

71 . A microfluidic device as recited in claim 53 , wherein said microfluidic device comprises a plurality of microcapillary devices.

72 . A microfluidic device as recited in claim 71 , wherein each of said microcapillary devices contains at least one amplification targeting reagent.

73 . A microfluidic device as recited in claim 71 , wherein at least said first sample chamber contains at least a first amplification targeting reagent, and at least a second microcapillary device contains at least a second amplification targeting reagent, said first amplification targeting reagent differing from said second amplification targeting reagent.

74 . A microfluidic device as recited in claim 53 , wherein said sample chamber comprises means for minimizing diffusion of said first sample portion.

75 . A microfluidic device as recited in claim 74 , wherein said means for minimizing diffusion comprises at least one feature selected from among glass beads, gels, absorbent particles and electrophoretic means.

76 . A microfluidic device as recited in claim 53 , wherein said microfluidic device further comprises a first fluid and a second fluid positioned in said first microcapillary device such that said first sample portion is disposed between said first fluid and said second fluid.

77 . A microfluidic device as recited in claim 76 , wherein said first fluid is immiscible with said first sample portion, and said second fluid is immiscible with said first sample portion.

78 . A microfluidic device as recited in claim 76 , wherein said first fluid and said second fluid have been cured.

79 . A microfluidic device as recited in claim 76 , wherein said first fluid and said second fluid each comprise a first composition.

80 . A microfluidic device as recited in claim 76 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

81 . A microfluidic device as recited in claim 53 , wherein said microfluidic device comprises a plurality of sample portions and a plurality of fluids positioned in said first microcapillary device, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

82 . A microfluidic device as recited in claim 53 , wherein said first sample chamber has an internal volume of about 100 nanoliters or less.

83 . A microfluidic device as recited in claim 53 , wherein said first sample chamber has an internal volume of about 10 nanoliters or less.

84 . A microfluidic device as recited in claim 53 , wherein said first sample chamber has an internal volume of about 1 nanoliter or less.

85 . A microfluidic device as recited in claim 53 , wherein said first sample portion has a volume of about 60 nanoliters or less.

86 . A microfluidic device as recited in claim 53 , wherein said first sample portion has a volume of about 100 nanoliters or less.

87 . A microfluidic device as recited in claim 53 , wherein said microfluidic device further comprises a sealing device adjacent to said first sample chamber.

88 . A microfluidic device as recited in claim 87 , wherein said sealing device is selected from the group consisting of microscope slide coverslips, tapes, films, silicon films, silicon devices, and devices comprising an array of reactants.

89 . A microfluidic device comprising:

a first sample chamber; and

at least one amplification targeting reagent positioned in said first sample chamber, said first sample chamber comprising at least a portion of an inside of a first microcapillary device,

whereby if a sample portion which contains at least a single molecule of said target nucleic acid is loaded in said first sample chamber, said first sample portion would attain a detectable concentration of said target nucleic acid within a portion of said first sample chamber after a single round of amplification.

90 . A microfluidic device as recited in claim 89 , wherein said first sample chamber further comprises constituents for enabling amplification of a target nucleic acid.

91 . A microfluidic device as recited in claim 89 , wherein if said first sample portion contains at least a single molecule of said target nucleic acid, said first sample portion would attain a detectable concentration of said target nucleic acid within a portion of said first sample chamber after a single amplification step.

92 . A microfluidic device as recited in claim 89 , wherein said microcapillary device comprises a planar capillary region.

93 . A microfluidic device as recited in claim 92 , wherein said first sample chamber has opposing barriers separated by 500 microns or less, said barriers defining said capillary region.

94 . A microfluidic device as recited in claim 93 , wherein said opposing barriers are separated by 100 microns or less.

95 . A microfluidic device as recited in claim 89 , wherein said first sample chamber has at least one dimension of 500 microns or less.

96 . A microfluidic device as recited in claim 95 , wherein said first sample chamber has at least one dimension of 100 microns or less.

97 . A microfluidic device as recited in claim 89 , wherein said first sample chamber has opposing barriers separated by 500 microns or less.

98 . A microfluidic device as recited in claim 97 , wherein said first sample chamber has opposing barriers separated by 100 microns or less.

99 . A microfluidic device as recited in claim 89 , wherein said microfluidic device comprises a plurality of microcapillary devices.

100 . A microfluidic device as recited in claim 99 , wherein each of said microcapillary devices contains at least one amplification targeting reagent.

101 . A microfluidic device as recited in claim 99 , wherein at least said first sample chamber contains at least a first amplification targeting reagent, and at least a second microcapillary device contains at least a second amplification targeting reagent, said first amplification targeting reagent differing from said second amplification targeting reagent.

102 . A microfluidic device as recited in claim 89 , wherein said sample chamber comprises means for minimizing diffusion of said first sample portion.

103 . A microfluidic device as recited in claim 102 , wherein said means for minimizing diffusion comprises at least one feature selected from among glass beads, gels, absorbent particles and electrophoretic means.

104 . A microfluidic device as recited in claim 89 , wherein said microfluidic device further comprises at least a first sample portion, a first fluid and a second fluid positioned in said microcapillary device such that said first sample portion is disposed between said first fluid and said second fluid.

105 . A microfluidic device as recited in claim 104 , wherein said first fluid is immiscible with said first sample portion, and said second fluid is immiscible with said first sample portion.

106 . A microfluidic device as recited in claim 104 , wherein said first fluid and said second fluid have been cured.

107 . A microfluidic device as recited in claim 104 , wherein said first fluid and said second fluid each comprise a first composition.

108 . A microfluidic device as recited in claim 104 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

109 . A microfluidic device as recited in claim 89 , wherein said microfluidic device further comprises a plurality of sample portions and a plurality of fluids positioned in said microcapillary device, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

110 . A microfluidic device as recited in claim 89 , wherein said first sample chamber has an internal volume of about 100 nanoliters or less.

111 . A microfluidic device as recited in claim 89 , wherein said first sample chamber has an internal volume of about 10 nanoliters or less.

112 . A microfluidic device as recited in claim 89 , wherein said first sample chamber has an internal volume of about 1 nanoliter or less.

113 . A microfluidic device as recited in claim 89 , wherein said microfluidic device further comprises a first sample portion positioned in said microcapillary, said first sample portion having a volume of about 60 nanoliters or less.

114 . A microfluidic device as recited in claim 89 , wherein said microfluidic device further comprises a first sample portion positioned in said microcapillary, said first sample portion having a volume of about 100 nanoliters or less.

115 . A microfluidic device as recited in claim 89 , wherein said first microcapillary device has an inner diameter in the range of from 20 micrometers to 75 micrometers.

116 . A microfluidic device as recited in claim 89 , wherein said first microcapillary device has an inner diameter of about 100 micrometers.

117 . A microfluidic device as recited in claim 89 , wherein said first microcapillary device has an inner diameter of about 100 micrometers or less.

118 . A microfluidic device as recited in claim 89 , wherein said first microcapillary device has an inner diameter of about 500 micrometers or less.

119 . A microfluidic device as recited in claim 89 , wherein said first microcapillary device has a length in the range of from about 1 mm to about 100 mm.

120 . A microfluidic device as recited in claim 89 , wherein said first microcapillary device has a length of about 4 cm.

121 . A microfluidic device as recited in claim 89 , wherein said first microcapillary device comprises at least two surfaces spaced from each other by about 20 micrometers or less.

122 . A method for detecting, for each of a plurality of sample portions, whether the sample portion contains at least one molecule of at least a first target nucleic acid, said method comprising:

loading sample portions of at least a first sample into a plurality of respective sample chambers, each said sample chamber comprising at least a portion of an inside of a microcapillary device, whereby if a sample portion loaded in one of said respective sample chambers contains at least a single molecule of said first target nucleic acid, said sample portion would attain a detectable concentration of said first target nucleic acid within a portion of said sample portion after a single round of amplification;

subjecting said sample portions to at least a first amplification step; and then

for each of a plurality of said sample portions, determining whether said sample portion contains at least one molecule of said first target nucleic acid.

123 . A method as recited in claim 122 , wherein said first amplification step is a homogeneous amplification step.

124 . A method as recited in claim 122 , wherein said first amplification step is a thermocycle step

125 . A method as recited in claim 122 , wherein if said first sample portion contains at least a single molecule of said first target nucleic acid, said first sample portion would attain a detectable concentration of said first target nucleic acid within a portion of said first sample chamber after a single amplification step.

126 . A method as recited in claim 122 , wherein each of said microcapillary devices comprises a planar capillary region.

127 . A method as recited in claim 126 , wherein each of said microcapillary devices has opposing barriers separated by 500 microns or less, said barriers defining said capillary region.

128 . A method as recited in claim 127 , wherein said opposing barriers are separated by 100 microns or less.

129 . A method as recited in claim 122 , wherein each of said sample chambers has at least one dimension of 500 microns or less.

130 . A method as recited in claim 129 , wherein each of said first sample chambers has at least one dimension of 100 microns or less.

131 . A method as recited in claim 122 , wherein each of said first sample chambers has opposing barriers separated by 500 microns or less.

132 . A method as recited in claim 131 , wherein each of said first sample chambers has opposing barriers separated by 100 microns or less.

133 . A method as recited in claim 122 , wherein at least a first of said sample chambers further comprises constituents for enabling amplification of said first target nucleic acid.

134 . A method as recited in claim 122 , wherein each said microcapillary device comprises sealed ends.

135 . A method as recited in claim 122 , wherein said method comprises loading portions of a single sample into a plurality of sample chambers and, for each sample chamber, determining whether the sample chamber contains said first target nucleic acid.

136 . A method as recited in claim 122 , wherein said method comprises loading portions of a single sample into a plurality of sample chamber and, for each of different sample chambers, determining whether the sample chamber contains one of a plurality of target nucleic acids.

137 . A method as recited in claim 136 , wherein said method comprises determining, for each of a first group of said sample chambers, whether the sample chamber contains said first target nucleic acid, and, for each of a second group of said sample chambers, whether the sample chamber contains a second target nucleic acid.

138 . A method as recited in claim 122 , wherein said method comprises loading at least one portion of a first sample into each of a first group of sample chambers, and loading at least one portion of a second sample into each of a second group of sample chambers.

139 . A method as recited in claim 138 , wherein said method comprises determining, for each of said first group of sample chambers, whether the sample chamber contains said first target nucleic acid, and, for each of said second group of sample chambers, whether the sample chamber contains a second target nucleic acid.

140 . A method as recited in claim 138 , wherein said method comprises determining, for each of said first and second groups of sample chambers, whether the sample chamber contains said first target nucleic acid.

141 . A method as recited in claim 122 , wherein at least one of said sample chambers comprises means for minimizing diffusion of said first sample portion.

142 . A method as recited in claim 141 , wherein said means for minimizing diffusion comprises at least one feature selected from among glass beads, gels, absorbent particles and electrophoretic means.

143 . A method as recited in claim 122 , wherein said method further comprises loading a first fluid and a second fluid into at least one of said microcapillary devices such that said first sample portion is disposed between said first fluid and said second fluid.

144 . A method as recited in claim 143 , wherein said first fluid is immiscible with said first sample portion, and said second fluid is immiscible with said first sample portion.

145 . A method as recited in claim 143 , wherein said method further comprises curing said first fluid and said second fluid.

146 . A method as recited in claim 143 , wherein said first fluid and said second fluid each comprise a first composition.

147 . A method as recited in claim 143 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

148 . A method as recited in claim 122 , wherein said method comprises loading a plurality of sample portions and a plurality of fluids into at least one of said microcapillary devices, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

149 . A method as recited in claim 122 , wherein said method further comprises positioning at least a first amplification targeting reagent in at least a first of said sample chambers.

150 . A method as recited in claim 149 , wherein said first amplification targeting reagent is positioned in said first sample chamber prior to loading a sample portion in said first sample chamber.

151 . A method as recited in claim 149 , wherein said first amplification targeting reagent is positioned in said first sample chamber while a sample portion is being loaded into said first sample chamber.

152 . A method as recited in claim 149 , wherein said first amplification targeting reagent is positioned in said first sample chamber after a sample portion is loaded into said first sample chamber.

153 . A method as recited in claim 122 , wherein said method further comprises positioning at least a first amplification targeting reagent in at least a first of said sample chambers and at least a second amplification targeting reagent in at least a second of said sample chambers.

154 . A method as recited in claim 122 , wherein said loading of said first sample portion is carried out using at least capillary action.

155 . A method as recited in claim 122 , wherein at least one of said sample chambers has an internal volume of about 100 nanoliters or less.

156 . A method as recited in claim 122 , wherein at least one of said sample chambers has an internal volume of about 10 nanoliter's or less.

157 . A method as recited in claim 122 , wherein at least one of said sample chambers has an internal volume of about 1 nanoliter or less.

158 . A method as recited in claim 122 , wherein said first sample portion has a volume of about 60 nanoliters or less.

159 . A method as recited in claim 122 , wherein said first sample portion has a volume of about 100 nanoliters or less.

160 . A microfluidic assembly, comprising:

at least a first microcapillary device, said microcapillary device defining at least a first sample chamber;

at least one reagent which enables amplification of a target nucleic acid, said at least one reagent being positioned within said sample chamber.

161 . A microfluidic device as recited in claim 160 , wherein if a first sample portion which contains at least a single molecule of said target nucleic acid is loaded into said first sample chamber, said first sample portion would attain a detectable concentration of said target nucleic acid within a portion of said first sample chamber after a single amplification step.

162 . A microfluidic device as recited in claim 160 , wherein said microcapillary device comprises a planar capillary region.

163 . A microfluidic device as recited in claim 162 , wherein said first sample chamber has opposing barriers separated by 500 microns or less, said barriers defining said capillary region.

164 . A microfluidic device as recited in claim 163 , wherein said opposing barriers are separated by 100 microns or less.

165 . A microfluidic device as recited in claim 160 , wherein said first sample chamber has at least one dimension of 500 microns or less.

166 . A microfluidic device as recited in claim 165 , wherein said first sample chamber has at least one dimension of 100 microns or less.

167 . A microfluidic device as recited in claim 160 , wherein said first sample chamber has opposing barriers separated by 500 microns or less.

168 . A microfluidic device as recited in claim 167 , wherein said first sample chamber has opposing barriers separated by 100 microns or less.

169 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device is positioned in a microfluidic device which comprises a plurality of microcapillary devices.

170 . A microfluidic device as recited in claim 169 , wherein each of said microcapillary devices contains at least one amplification targeting reagent.

171 . A microfluidic device as recited in claim 169 , wherein at least said first sample chamber contains at least a first amplification targeting reagent, and at least a second microcapillary device contains at least a second amplification targeting reagent, said first amplification targeting reagent differing from said second amplification targeting reagent.

172 . A microfluidic device as recited in claim 160 , wherein said first sample chamber comprises means for minimizing diffusion of a sample portion if said sample portion is positioned in said first sample chamber.

173 . A microfluidic device as recited in claim 172 , wherein said means for minimizing diffusion comprises at least one feature selected from among glass beads, gels, absorbent particles and electrophoretic means.

174 . A microfluidic device as recited in claim 160 , wherein at least a first sample portion, a first fluid and a second fluid are positioned in said microcapillary device such that said first sample portion is disposed between said first fluid and said second fluid.

175 . A microfluidic device as recited in claim 174 , wherein said first fluid is immiscible with said first sample portion, and said second fluid is immiscible with said first sample portion.

176 . A microfluidic device as recited in claim 174 , wherein said first fluid and said second fluid have been cured.

177 . A microfluidic device as recited in claim 174 , wherein said first fluid and said second fluid each comprise a first composition.

178 . A microfluidic device as recited in claim 174 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

179 . A microfluidic device as recited in claim 160 , wherein a plurality of sample portions and a plurality of fluids are positioned in said microcapillary device, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

180 . A microfluidic device as recited in claim 160 , wherein said first sample chamber has an internal volume of about 100 nanoliters or less.

181 . A microfluidic device as recited in claim 160 , wherein said first sample chamber has an internal volume of about 10 nanoliters or less.

182 . A microfluidic device as recited in claim 160 , wherein said first sample chamber has an internal volume of about 1 nanoliter or less.

183 . A microfluidic device as recited in claim 160 , wherein a first sample portion is positioned in said first sample chamber, said first sample portion having a volume of about 60 nanoliters or less.

184 . A microfluidic device as recited in claim 160 , wherein a first sample portion is positioned in said first sample chamber, said first sample portion having a volume of about 100 nanoliters or less.

185 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device has an inner diameter in the range of from 20 micrometers to 75 micrometers.

186 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device has an inner diameter of about 100 micrometers.

187 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device has an inner diameter of about 100 micrometers or less.

188 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device has an inner diameter of about 500 micrometers or less.

189 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device has a length in the range of from about 1 mm to about 100 mm.

190 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device has a length of about 4 cm.

191 . A microfluidic device as recited in claim 160 , wherein said first microcapillary device comprises at least two surfaces spaced from each other by about 20 micrometers or less.

192 . A method for detecting whether at least one molecule of a first target nucleic acid is present in a first sample portion, said method comprising:

loading a first sample into a first region of a sample retaining means positioned within a microcapillary device, said first sample comprising at least part of a fluid sample, whereby if a first portion of said first sample contains at least a single molecule of said target nucleic acid, said first portion of said first sample would attain a detectable concentration of said target nucleic acid within a first portion of said sample retaining means after a single round of amplification;

subjecting said first portion of said first sample to at least a first amplification step; and then

determining whether said first portion of said first sample contains at least one molecule of said target nucleic acid.

193 . A method as recited in claim 192 , wherein said sample retaining means comprises at least one member selected from among the group consisting of glass beads, gels, absorbent particles, barrier means and electrophoretic means.

194 . A method as recited in claim 193 , wherein said method further comprises:

subjecting a second portion of said first sample to at least a first amplification step; and then

determining whether said second portion of said first sample contains at least one molecule of said target nucleic acid.

195 . A method as recited in claim 193 , wherein said method further comprises:

loading a second sample into a second region of said sample retaining means, said second sample portion comprising a part of said fluid sample, whereby if said second sample contains at least a single molecule of said target nucleic acid, said second sample would attain a detectable concentration of said target nucleic acid after a single round of amplification;

subjecting said second sample to at least a first amplification step; and then

determining whether said second sample contains at least one molecule of said target nucleic acid.

196 . A method as recited in claim 193 , wherein said microcapillary device comprises at least one surface which exhibits at least one characteristic selected from the group consisting of hydrophobicity, hydrophilicity, electromagnetic force exertion and electrostatic force exertion.

197 . A method as recited in claim 193 , wherein said microcapillary device is tubular or linear.

198 . A method as recited in claim 193 , wherein said microcapillary device is planar.

199 . A method as recited in claim 198 , wherein said sample retaining means is positioned between opposing barriers separated by 500 microns or less, said barriers defining a capillary region of said capillary device.

200 . A method as recited in claim 199 , wherein said opposing barriers are separated by 100 microns or less.

201 . A method as recited in claim 193 , wherein said method further comprises loading a first fluid and a second fluid into said first microcapillary device such that said first portion of said first sample is disposed between said first fluid and said second fluid.

202 . A method as recited in claim 201 , wherein said first fluid is immiscible with said first portion of said first sample, and said second fluid is immiscible with said first sample portion.

203 . A method as recited in claim 201 , wherein said method further comprises curing said first fluid and said second fluid.

204 . A method as recited in claim 201 , wherein said first fluid and said second fluid each comprise a first composition.

205 . A method as recited in claim 201 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

206 . A method as recited in claim 193 , wherein said method comprises loading a plurality of sample portions and a plurality of fluids into said first microcapillary device, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

207 . A method as recited in claim 193 , wherein said method further comprises positioning at least a first amplification targeting reagent in said first region of said sample retaining means.

208 . A method as recited in claim 193 , wherein said sample retaining means has at least one dimension of 500 microns or less.

209 . A method as recited in claim 208 , wherein said sample retaining means has at least one dimension of 100 microns or less.

210 . A method as recited in claim 193 , wherein said sample retaining means is positioned between opposing barriers separated by 500 microns or less.

211 . A method as recited in claim 210 , wherein said sample retaining means is positioned between opposing barriers separated by 100 microns or less.

212 . A method as recited in claim 192 , wherein said method further comprises:

subjecting a second portion of said first sample to at least a first amplification step; and then

determining whether said second portion of said first sample contains at least one molecule of said target nucleic acid.

213 . A method as recited in claim 192 , wherein said method further comprises:

loading a second sample into a second region of said sample retaining means, said second sample portion comprising a part of said fluid sample, whereby if said second sample contains at least a single molecule of said target nucleic acid, said second sample would attain a detectable concentration of said target nucleic acid after a single round of amplification;

subjecting said second sample to at least a first amplification step; and then

determining whether said second sample contains at least one molecule of said target nucleic acid.

214 . A method as recited in claim 192 , wherein said microcapillary device comprises at least one surface which exhibits at least one characteristic selected from the group consisting of hydrophobicity, hydrophilicity, electromagnetic force exertion and electrostatic force exertion.

215 . A method as recited in claim 192 , wherein said microcapillary device is tubular or linear.

216 . A method as recited in claim 192 , wherein said microcapillary device is planar.

217 . A method as recited in claim 192 , wherein said method further comprises loading a first fluid and a second fluid into said first microcapillary device such that said first portion of said first sample is disposed between said first fluid and said second fluid.

218 . A method as recited in claim 217 , wherein said first fluid is immiscible with said first portion of said first sample, and said second fluid is immiscible with said first sample portion.

219 . A method as recited in claim 217 , wherein said method further comprises curing said first fluid and said second fluid.

220 . A method as recited in claim 217 , wherein said first fluid and said second fluid each comprise a first composition.

221 . A method as recited in claim 217 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

222 . A method as recited in claim 192 , wherein said method comprises loading a plurality of sample portions and a plurality of fluids into said first microcapillary device, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

223 . A method as recited in claim 192 , wherein said method further comprises positioning at least a first amplification targeting reagent in said first region of said sample retaining means.

224 . A method as recited in claim 192 , wherein said sample retaining means has at least one dimension of 500 microns or less.

225 . A method as recited in claim 224 , wherein said sample retaining means has at least one dimension of 100 microns or less.

226 . A method as recited in claim 192 , wherein said sample retaining means is positioned between opposing barriers separated by 500 microns or less.

227 . A method as recited in claim 226 , wherein said sample retaining means is positioned between opposing barriers separated by 100 microns or less.

228 . A method as recited in claim 192 , wherein said first target nucleic acid comprises at least one nucleic acid sequence of at least one pathogenic organism.

229 . A method as recited in claim 192 , wherein said first sample portion comprises at least one forensic sample.

230 . A method as recited in claim 192 , wherein said first target nucleic acid is indicative of the likelihood or presence of at least one genetic disorder.

231 . A method as recited in claim 192 , wherein said method for detecting whether at least one molecule of said first target nucleic acid is present in said first sample portion is part of a procedure selected from among the group consisting of analyzing mutations in activated oncogenes, molecular cloning, analyzing DNA, and detecting at least one sequence difference.

232 . A method as recited in claim 231 , wherein said procedure comprises at least one task selected from among the group consisting of generating specific sequences of DNA for cloning or use as probes, detecting segments of DNA for genetic mapping, detecting expressed sequences by amplification of particular segments of cDNA, analyzing expressed sequences by amplification of particular segments of cDNA, generating libraries of cDNA from small amounts of mRNA, generating large amounts of DNA for sequencing, analyzing mutations, and chromosome crawling.

233 . A method as recited in claim 231 , wherein said sequence difference is selected from among insertions, deletions and changes.

234 . A method as recited in claim 192 , wherein said method for detecting whether at least one molecule of said first target nucleic acid is present in said first sample portion is part of a procedure selected from among the group consisting of fertility procedures, immunology procedures, cytology procedures, gas analysis procedures and pharmaceutical screening procedures.

235 . A microfluidic device comprising:

at least a first microcapillary device comprising at least a first microcapillary region;

at least a first sample retaining means positioned within said first microcapillary region; and

at least a first sample portion, said first sample portion being positioned in at least a first region of said first sample retaining means, whereby if said first sample portion contains at least a single molecule of a target nucleic acid, said first sample portion would attain a detectable concentration of said target nucleic acid after a single round of amplification.

236 . A microfluidic device as recited in claim 235 , wherein said first sample retaining means comprises at least one feature selected from among glass beads, gels, absorbent particles, barrier means and electrophoretic means.

237 . A microfluidic device as recited in claim 235 , wherein said first region of said first sample retaining means further comprises constituents for enabling amplification of a target nucleic acid.

238 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region is planar.

239 . A microfluidic device as recited in claim 238 , wherein said first microfluidic device comprises opposing barriers separated by 500 microns or less, said barriers defining said microcapillary region.

240 . A microfluidic device as recited in claim 239 , wherein said opposing barriers are separated by 100 microns or less.

241 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has an inner diameter in the range of from 20 micrometers to 75 micrometers.

242 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has an inner diameter of about 100 micrometers.

243 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has an inner diameter of about 100 micrometers or less.

244 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has an inner diameter of about 500 micrometers or less.

245 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has a length in the range of from about 1 mm to about 100 mm.

246 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has a length of about 4 cm.

247 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region comprises at least two surfaces spaced from each other by about 20 micrometers or less.

248 . A microfluidic device as recited in claim 235 , wherein said microfluidic device further comprises at least a first amplification targeting reagent positioned in said first microcapillary region.

249 . A microfluidic device as recited in claim 235 , wherein said microfluidic device comprises a plurality of microcapillary devices.

250 . A microfluidic device as recited in claim 235 , wherein each of said microcapillary devices contains at least one amplification targeting reagent.

251 . A microfluidic device as recited in claim 250 , wherein at least said first microcapillary region contains at least a first amplification targeting reagent, and at least a second microcapillary device contains at least a second amplification targeting reagent, said first amplification targeting reagent differing from said second amplification targeting reagent.

252 . A microfluidic device as recited in claim 235 , wherein said microfluidic device further comprises a first fluid and a second fluid positioned in said first microcapillary device such that said first sample portion is disposed between said first fluid and said second fluid.

253 . A microfluidic device as recited in claim 252 , wherein said first fluid is immiscible with said first sample portion, and said second fluid is immiscible with said first sample portion.

254 . A microfluidic device as recited in claim 252 , wherein said first fluid and said second fluid have been cured.

255 . A microfluidic device as recited in claim 252 , wherein said first fluid and said second fluid each comprise a first composition.

256 . A microfluidic device as recited in claim 252 , wherein at least one of said first and second fluids comprises at least one fluid selected from among the group consisting of mineral oils, gases and curable monomer formulations.

257 . A microfluidic device as recited in claim 235 , wherein said microfluidic device comprises a plurality of sample portions and a plurality of fluids positioned in said first microcapillary device, each of said sample portions having first and second ends in contact with respective fluids with which said sample portion is immiscible.

258 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has an internal volume of about 100 nanoliters or less.

259 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has an internal volume of about 10 nanoliters or less.

260 . A microfluidic device as recited in claim 235 , wherein said first microcapillary region has an internal volume of about 1 nanoliter or less.

261 . A microfluidic device as recited in claim 235 , wherein said first sample portion has a volume of about 60 nanoliters or less.

262 . A microfluidic device as recited in claim 235 , wherein said first sample portion has a volume of about 100 nanoliters or less.

263 . A microfluidic device comprising:

at least a first microcapillary device comprising at least a first microcapillary region;

at least a first sample retaining means positioned within said first microcapillary region; and

at least one amplification targeting reagent positioned in at least a first region of said first sample retaining means,

whereby if a sample portion which contains at least a single molecule of a target nucleic acid is loaded in said first region of said first sample retaining means, said sample portion would attain a detectable concentration of said target nucleic acid after a single round of amplification.

264 . A microfluidic device as recited in claim 263 , wherein said first sample retaining means comprises at least one feature selected from among glass beads, gels, absorbent particles, barrier means and electrophoretic means.

265 . A microfluidic device as recited in claim 263 , wherein said first region of said first sample retaining means further comprises constituents for enabling amplification of a target nucleic acid.

266 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region is planar.

267 . A microfluidic device as recited in claim 266 , wherein said first microfluidic device comprises opposing barriers separated by 500 microns or less, said barriers defining said microcapillary region.

268 . A microfluidic device as recited in claim 267 , wherein said opposing barriers are separated by 100 microns or less.

269 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has an inner diameter in the range of from 20 micrometers to 75 micrometers.

270 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has an inner diameter of about 100 micrometers.

271 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has an inner diameter of about 100 micrometers or less.

272 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has an inner diameter of about 500 micrometers or less.

273 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has a length in the range of from about 1 mm to about 100 mm.

274 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has a length of about 4 cm.

275 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region comprises at least two surfaces spaced from each other by about 20 micrometers or less.

276 . A microfluidic device as recited in claim 263 , wherein said microfluidic device further comprises at least a first amplification targeting reagent positioned in said first microcapillary region.

277 . A microfluidic device as recited in claim 263 , wherein said microfluidic device comprises a plurality of microcapillary devices.

278 . A microfluidic device as recited in claim 277 , wherein each of said microcapillary devices contains at least one amplification targeting reagent.

279 . A microfluidic device as recited in claim 277 , wherein at least said first microcapillary region contains at least a first amplification targeting reagent, and at least a second microcapillary device contains at least a second amplification targeting reagent, said first amplification targeting reagent differing from said second amplification targeting reagent.

280 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has an internal volume of about 100 nanoliters or less.

281 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has an internal volume of about 10 nanoliters or less.

282 . A microfluidic device as recited in claim 263 , wherein said first microcapillary region has an internal volume of about 1 nanoliter or less.