Fig. 2: Efficient electrode geometry for digitally driven, wireless open-channel fluidics.

a Scanning electron microscopy (SEM) cross-section of our electrode stack after fabrication with a sidewall angle, α, clearly defined. b Theoretical threshold-voltage curves were plotted as a function of α, using our measured device parameters with ±1 standard deviation. This was simulated for both dielectric (DI water) and ionic (PBS) solutions. Experimental data for both regimes are in good agreement. c The theoretical and observed voltage gain is plotted as a function of frequency for nonresonant, resonant, and wireless resonant operation. A wireless NFC circuit was also designed and powered using a smartphone to actuate PBS buffer. A theoretical curve to simulate the complex circuitry within the smartphone device was fitted to the observed data using our known circuit elements. d The required input voltage experimentally found for DI water and PBS buffer for three different device configurations: wired nonresonant, wired resonant (via a series inductor), and resonant wireless using inductively coupled coils (1–1.5 cm separation). With resonant operation, the input voltage for both dielectric and conductive solutions is below the threshold for a digital logic signal. Error bars are ±1 standard deviation. Source data are provided as a Source Data file for Fig. 1b, d.