DIGITAL MICROFLUIDIC DEVICES INCLUDING DUAL SUBSTRATES WITH THIN-FILM TRANSISTORS AND CAPACITIVE SENSING
An active matrix electrowetting on dielectric (AM-EWoD) device including a top substrate with driving electrodes and capacitive sensing. As depicted herein the bottom substrate includes a first plurality of electrodes to propel various droplets through a microfluidic region, while the top substrate includes a second plurality of electrodes that are configured to interrogate the droplets with capacitive sensing. In some embodiments, the top substrate has zones of high-resolution sensing and zones of low-resolution sensing.
1 . A digital microfluidic device, comprising:
a first substrate comprising a plurality of propulsion electrodes coupled to a set of thin-film-transistors, and including a hydrophobic layer covering both the plurality of propulsion electrodes and the set of thin-film-transistors;
a second substrate comprising
a first plurality of sensing electrodes and a first plurality of drive electrodes in a first area of the second substrate, wherein the density of sensing electrodes in the first area is between 20 and 200 sensing electrodes per linear centimeter;
a second plurality of sensing electrodes and a second plurality of drive electrodes in a second area of the second substrate wherein the density of sensing electrodes in the second area is between 1 and 15 sensing electrodes per linear centimeter;
a spacer separating the first and second substrates and creating a microfluidic region between the first and second substrates;
a controller operatively coupled to the set of thin-film-transistors and configured to provide a propulsion voltage between at least a portion of the propulsion electrodes and the first plurality of drive electrodes and the second plurality of drive electrodes.
2 . The digital microfluidic device of claim 1 , wherein the set of thin-film-transistors comprises amorphous silicon.
3 . The digital microfluidic device of claim 1 , wherein the plurality of propulsion electrodes are arranged in an array.
4 . The digital microfluidic device of claim 3 , wherein the array of propulsion electrodes includes at least 25 propulsion electrodes per linear centimeter.
5 . The digital microfluidic device of claim 1 , wherein the sensing electrodes in the second plurality of sensing electrodes are between 0.01 and 5 mm in width.
6 . The digital microfluidic device of claim 1 , wherein the second substrate includes at least one light-transmissive region.
7 . The digital microfluidic device of claim 6 , wherein the light-transmissive region is at least 10 mm 2 in area.
8 . The digital microfluidic device of claim 1 , wherein the density of sensing electrodes in the first area is at least three times as many sensing electrodes per 100 mm 2 as the density of sensing electrodes in the second area.
9 . The digital microfluidic device of claim 1 , wherein the first area is smaller than the second area.
10 . The digital microfluidic device of claim 9 , wherein the second area is at least three times larger than the first area.
11 . The digital microfluidic device of claim 1 , wherein the first plurality of sensing electrodes, the first plurality of drive electrodes, the second plurality of sensing electrodes, and the second plurality of drive electrodes are all covered by a second hydrophobic layer.
12 . The digital microfluidic device of claim 1 , further comprising a dielectric layer between the hydrophobic layer and the plurality of propulsion electrodes and the set of thin-film-transistors.