Digital microfluidic devices including dual substrates with thin-film transistors and capacitive sensing

Abstract

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.