COMPOSITIONS AND METHODS TO FABRICATE A PHOTOACTIVE SUBSTRATE SUITABLE FOR SHAPED GLASS STRUCTURES
A shaped photosensitive glass composition comprising silica, K 2 O, Na 2 O, Ag 2 O, B 2 O 3 , Al 2 O 3 , Li 2 O, and CeO 2 with a high anisotropic-etch ratio formed by a novel construction method. Furthermore, such shaped glass structures can be used to form a negative mold for casting the shape in other materials. Structures of the photosensitive glass composition may include micro-channels, micro-optics, microposts, or arrays of hollow micro-needles.
1 . A shaped glass structure with a high anisotropic-etch ratio comprising:
a photosensitive glass substrate with a glass transformation temperature, wherein the photosensitive glass substrate comprises:
a glass composition comprising
60-76 weight % silica,
6 weight %-16 weight % of a combination of K 2 O and Na 2 O with
at least 3 weight % K 2 O,
0.001-1 weight % Ag 2 O,
0.75 weight %-7 weight % B 2 O 3 , and
5-8 weight % Al 2 O 3 , with the combination of B 2 O 3 , and Al 2 O 3 not exceeding 13 weight %,
8-15 weight % Li 2 O, and
0.04-0.1 weight % CeO 2 , and
one or more patterned structure.
2 . The shaped glass structure of claim 1 , wherein the patterned structure comprises at least one portion exposed to an activating energy source, such as ultraviolet light, while leaving at least a second portion of the glass substrate unexposed, wherein at least a part of the exposed portion is a crystalline material formed by heating the glass substrate to a temperature near the glass transformation temperature, wherein when etching the glass substrate in an etchant, the anisotropic-etch ratio of the exposed portion to the unexposed portion is at least 30:1 when the glass is exposed to a broad spectrum mid-ultraviolet flood lamp, to provide a shaped glass structure with an aspect ratio of at least 30:1, and to provide shaped glass structures with an aspect ratio much greater than 30:1 when the glass is exposed using a high powered energy source, such as a laser.
3 . The shaped glass structure of claim 1 , wherein the glass composition is essentially germanium-free.
4 . The shaped glass structure of claim 1 , wherein the glass composition comprises at least 0.5 weight % B 2 O 3 .
5 . The shaped glass structure of claim 1 , wherein the glass composition comprises at least 1.25 weight % B 2 O 3 .
6 . The shaped glass structure of claim 1 , wherein the glass composition comprises at least 0.3 weight % Sb 2 O 3 or As 2 O 3 .
7 . The shaped glass structure of claim 1 , wherein the glass composition comprises 0.003-1 weight % Au 2 O.
8 . The shaped glass structure claim 1 , wherein the glass composition contains 1-18 weight % of an oxide selected from the group consisting of CaO, ZnO, PbO, MgO and BaO.
9 . The shaped glass structure of claim 1 , wherein the glass composition contains 0-5 weight %, iron (Fe 2 O 3 ) to make the composition paramagnetic and/or to use iron (II) and iron (III) to quench intrinsic autofluorescence.
10 . The shaped glass structure of claim 1 , wherein the glass composition comprises up to 2 weight % Copper Oxide.
11 . The shaped glass structure of claim 1 , wherein the anisotropic-etch ratio of exposed portion to the unexposed portion is 30-45:1.
12 . The shaped glass structure of claim 22 , wherein the anisotropic-etch ratio of exposed portion to said unexposed portion is at least one of 10-20:1; 21-29:1; 30-45:1; 20-40:1; 41-45:1; and 30-50:1.
13 . The shaped glass structure of claim 1 , wherein the etchant comprises hydrofluoric acid.
14 . The shaped glass structure of claim 1 , wherein the wavelength of the ultraviolet light is about 308-312 nm.