Electric field gradient focusing device

1 . An electric field gradient focusing device comprising:

a fluidic channel having an inlet and an outlet for a fluid;

a first actuator comprising a first plurality of electrodes adjacent to the fluidic channel;

an AC voltage source that is operatively coupled to the first plurality of electrodes of the first actuator and configured to apply an AC voltage across the first plurality of electrodes, thereby inducing fluid flow in the fluidic channel via electroosmosis;

a second actuator comprising a second plurality of electrodes adjacent to the fluidic channel;

a plurality of pairs of side-chambers and a first array of semi-permeable membranes along a first wall of the fluidic channel and a second array of semi-permeable membranes along a second wall of the fluidic channel, the first wall and the second wall arranged on opposite sides of the fluidic channel, wherein the plurality of pairs of side-chambers are arranged such that a first side-chamber of a pair of side-chambers is connected to the first wall of the fluidic channel by a respective semi-permeable membrane of the first array of semi-permeable membranes, wherein a second side-chamber of the pair of side-chambers is connected to the second wall at a same position longitudinally along the fluidic channel as the first side-chamber by a respective semi-permeable membrane of the second array of semi-permeable membranes, wherein each semi-permeable membrane is conductive to ions, and wherein the second actuator comprises a pair of electrodes of the second plurality of electrodes in each of the plurality of pairs of side-chambers;

a DC voltage source that is operatively coupled to the second plurality of electrodes of the second actuator and configured to apply a DC voltage across the second plurality of electrodes, thereby generating a nonuniform DC electric field gradient longitudinally along at least part of the fluidic channel.

2 . The electric field gradient focusing device of claim 1 , wherein the first actuator comprises a first array of electrode pairs of the first plurality of electrodes along a wall of the fluidic channel, wherein the first actuator comprises first conductors configured to electrically connect the first array of electrode pairs to the AC voltage source in such a way that an AC electric field can be generated between a first electrode and a second electrode of each electrode pair, and wherein each electrode pair is composed of electrodes differing by at least one of their geometry or their elevation with respect to the wall of the fluidic channel.

3 . The electric field gradient focusing device of claim 2 , wherein the AC voltage source is connected to the first electrode of each of at least two electrode pairs of the first array of electrode pairs.

4 . The electric field gradient focusing device of claim 2 , wherein the first actuator is configured to apply a further DC voltage at each electrode of the first array of electrode pairs that is within 0.02 V of the DC voltage of the DC electric field gradient in the fluidic channel.

5 . The electric field gradient focusing device of claim 2 , wherein the first array of electrode pairs comprises at least two groups of electrode pairs, wherein a frequency and/or an amplitude of the AC electric field generated between the first and second electrodes of each electrode pair is different for each of the at least two groups of electrode pairs.

6 . The electric field gradient focusing device of claim 2 , wherein the second actuator comprises at least two electrodes of the second plurality of electrodes and second conductors configured to electrically connect the at least two electrodes to the DC voltage source, wherein the first array of electrode pairs of the first actuator are different from the at least two electrodes of the second actuator.

7 . The electric field gradient focusing device of claim 6 , wherein the at least two electrodes of the second actuator are Faradaic electrodes.

8 . The electric field gradient focusing device of claim 1 , wherein the first array of semi-permeable membranes has a conductance per area towards cations of at least 0.1 S/m 2 at 30° C. and 70% relative humidity and a conductance per area towards anions that is at least 10 times lower at 30° C. and 70% relative humidity than the conductance per area towards cations for the first array of semi-permeable membranes, and wherein the second array of semi-permeable membranes has a conductance per area towards anions of at least 0.1 S/m 2 at 30° C. and 70% relative humidity and a conductance per area towards cations that is at least 10 times lower at 30° C. and 70% relative humidity than the conductance per area towards anions for the second array of semi-permeable membranes.

9 . A microfluidic chip comprising the electric field gradient focusing device of claim 1 .

10 . The electric field gradient focusing device of claim 1 , wherein the pairs of electrodes in each of the plurality of pairs of side-chambers are each configured with one electrode in a respective first side-chamber and one electrode in a respective second side chamber that is paired with the respective first side-chamber, and wherein the second actuator and the DC voltage source are configured to generate a DC voltage bias between each pair of electrodes in each pair of side-chambers.

11 . The electric field gradient focusing device of claim 10 , wherein, for a given pair of side-chambers, the first side-chamber is configured to be at a higher voltage than the second side-chamber.

12 . The electric field gradient focusing device of claim 10 , wherein the plurality of pairs of side-chambers are arranged such that an absolute field strength of the DC voltage bias between the pairs of electrodes is lowest near the inlet of the fluidic channel and increases longitudinally along the fluidic channel.

13 . A system for particle separation comprising:

an electric field gradient focusing device comprising:

a fluidic channel having an inlet and an outlet for a fluid;

a first actuator comprising a first plurality of electrodes adjacent to the fluidic channel;

a second actuator comprising a second plurality of electrodes adjacent to the fluidic channel; and

a plurality of pairs of side-chambers and a first array of semi-permeable membranes along a first wall of the fluidic channel and a second array of semi-permeable membranes along a second wall of the fluidic channel, the first wall and the second wall arranged on opposite sides of the fluidic channel, wherein the plurality of pairs of side-chambers are arranged such that a first side-chamber of a pair of side-chambers is connected to the first wall of the fluidic channel by a respective semi-permeable membrane of the first array of semi-permeable membranes, wherein a second side-chamber of the pair of side-chambers is connected to the second wall at a same position longitudinally along the fluidic channel as the first side-chamber by a respective semi-permeable membrane of the second array of semi-permeable membranes, wherein each semi-permeable membrane is conductive to ions, and wherein the second actuator comprises a pair of electrodes of the second plurality of electrodes in each of the plurality of pairs of side-chambers;

a fluidic input configured to provide a fluid comprising a mixture of charged particles comprising a first charged particle; and

a controller comprising one or more processors that are operatively coupled to the first plurality of electrodes of the first actuator and to the second plurality of electrodes of the second actuator and that are configured to: (i) apply an AC voltage across the first plurality of electrodes of the first actuator, thereby inducing a fluid flow in the fluidic channel via electroosmosis and (ii) apply a DC voltage across the second plurality of electrodes of the second actuator, thereby generating a nonuniform DC electric field gradient longitudinally along at least part of the fluidic channel.

14 . The system for particle separation of claim 13 , wherein the first actuator comprises a first array of electrode pairs of the first plurality of electrodes along a wall of the fluidic channel, wherein the first actuator comprises first conductors configured to electrically connect the first array of electrode pairs to an AC power source in such a way that an AC electric field can be generated between a first electrode and a second electrode of each electrode pair, and wherein each electrode pair is composed of electrodes differing by at least one of their geometry or their elevation with respect to the wall of the fluidic channel.

15 . The system for particle separation of claim 14 , wherein the second actuator comprises at least two electrodes of the second plurality of electrodes and second conductors configured to electrically connect the at least two electrodes to a DC power source, wherein the first array of electrode pairs of the first actuator are different from the at least two electrodes of the second actuator.

16 . The system for particle separation of claim 13 , wherein the first array of semi-permeable membranes has a conductance per area towards cations of at least 0.1 S/m 2 at 30° C. and 70% relative humidity and a conductance per area towards anions that is at least 10 times lower at 30° C. and 70% relative humidity than the conductance per area towards cations for the first array of semi-permeable membranes, and wherein the second array of semi-permeable membranes has a conductance per area towards anions of at least 0.1 S/m 2 at 30° C. and 70% relative humidity and a conductance per area towards cations that is at least 10 times lower at 30° C. and 70% relative humidity than the conductance per area towards anions for the second array of semi-permeable membranes.

17 . A system for particle separation comprising:

an electric field gradient focusing device comprising:

a fluidic channel having an inlet and an outlet for a fluid;

a first actuator comprising a first plurality of electrodes adjacent to the fluidic channel;

an AC voltage source that is operatively coupled to the first plurality of electrodes of the first actuator and configured to apply an AC voltage across the first plurality of electrodes of the first actuator, thereby inducing fluidic flow in the fluidic channel via electroosmosis;

a second actuator comprising a second plurality of electrodes adjacent to the fluidic channel;

a DC voltage source that is operatively coupled to the second plurality of electrodes of the second actuator and configured to apply a DC voltage across the second plurality of electrodes of the second actuator, thereby inducing a DC electric field gradient longitudinally along at least part of the fluidic channel;

a side-chamber having an inlet and an outlet for a fluid, wherein the side-chamber extends longitudinally along a length of the fluidic channel; and

a semi-permeable membrane that extends longitudinally along the length of the fluidic channel, separating the fluidic channel from the side-chamber;

a first fluidic input configured to provide a first fluid comprising a mixture of charged particles comprising a first charged particle and a first concentration of an ion to the inlet of the fluidic channel; and

a second fluidic input configured to provide a second fluid to the inlet of the side-chamber, wherein the second fluid has a second concentration of the ion that is less than the first concentration of the ion in the first fluid and wherein providing the second fluid to the inlet of the side-chamber induces a gradient in concentration of the ion in the fluidic channel along at least a portion of the fluidic channel such that the DC electric field gradient along the portion of the fluidic channel is nonuniform, wherein the gradient in concentration of the ion is induced by ions from the fluidic channel passing through the semi-permeable membrane that connects the side-chamber to the fluidic channel, and wherein the semi-permeable membrane is not permeable to the first charged particle.

18 . The system for particle separation of claim 17 , wherein the first actuator comprises a first array of electrode pairs of the first plurality of electrodes along a wall of the fluidic channel, wherein the first actuator comprises first conductors configured to electrically connect the first array of electrode pairs to the AC voltage source in such a way that an AC electric field can be generated between a first electrode and a second electrode of each electrode pair, and wherein each electrode pair is composed of electrodes differing by at least one of their geometry or their elevation with respect to the wall of the fluidic channel.

19 . The system for particle separation of claim 18 , wherein the second actuator comprises at least two electrodes of the second plurality of electrodes and second conductors configured to electrically connect the at least two electrodes to the DC voltage source, wherein the first array of electrode pairs of the first actuator are different from the at least two electrodes of the second actuator.