Novel CMOS Thermo-Capacitive Sensing Method for Lab-on-Chip Applications.

This paper introduces a novel droplet-sensing platform enabling precise monitoring of droplet evaporation. The platform includes a capacitive interface circuit connected to a 256-electrode array, allowing for the measurement of small capacitance changes when the electrodes are exposed to chemical solvents. While capacitive sensors offer advantages in measuring dielectric changes, their effectiveness in reliably monitoring small changes during droplet evaporation, especially in low-alcohol concentration water-alcohol mixtures, is limited. The study highlights the challenges associated with using capacitive sensors for this purpose and proposes a novel approach that analyzes the duration of droplet presence before evaporation as a crucial parameter for assessing suitable mixtures in life science applications. Experimental results from our thermo-capacitive sensing method demonstrate that, in open-top sensing conditions, the average time of evaporation (ToE) change ratio (TCR) for water-alcohol mixtures is approximately 5 to 7 times higher than the average capacitance change ratio (CCR). This research aims to advance droplet monitoring techniques in various scientific applications.