SAM CHIN

Capacitive Droplet Sensing | 2017

Droplet and Touch sensing using PSOc

I worked on prototyping capacitive sensing for programmable droplets - a platform that moves water droplets through a grid using electrowetting. All robust actuation systems require feedback; my work begins adding droplet and touch sensing to the platform.

Each pad had a different raw capacitance due to differences dielectric thickness and pad irregularities. I created test platform and a calibration process to normalize droplet and touch events for a small number of pads.

After normalizing droplet presence and touch, I tested a number of different liquids (coffee, salt water, de-ionized water, milk) to see if they were distinguishable. Through this testing I learned that the coupling between pads through the water had a much larger effect on the capacitance than the intrinsic qualities of the liquid.