DropleX: Liquid sensing using tablet touchscreens

Capacitive touchscreens on smart devices such as tablets have conventionally been designed to reject the effects of liquids such as raindrops, treating them as unwanted noise. In this work, we take the opposite approach and investigate whether commodity capacitive touchscreens can instead be repurposed to perform liquid sensing.

To do this, we have developed a physics-informed mechanism that disables the touchscreen's built-in adaptive filters, originally designed to reject the effects of liquid drops such as rain, without any hardware modifications.

We will investigate microliter-scale adulteration in soda, wine, and milk, threshold detection of trace chemical concentrations, and through-container adulterant detection to detect if a drink has been spiked or if a sealed liquid has been contaminated. Given the predominance of touchscreens, this project can open new opportunities for liquid sensing on everyday devices.