Electrolyte concentration effects on DC voltage electrowetting

• Published in: Sensors and actuators. A. Physical. Vol. 240; pp. 126 - 130
• Main Authors: Sawane, Yogesh B., Wadhai, Sandip M., Limaye, A.V., Banpurkar, Arun G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2016
• Subjects: DC electrowetting; Direct current; Droplets; Electric potential; Electrodes; Electrolyte concentration; Electrolytes; Liquids; Planar and interdigitated electrode; PMMA-teflon bilayer for consistent EW in air ambient; Reduction (electrolytic); Voltage; Electrolyte concentration; DC electrowetting; PMMA-teflon bilayer for consistent EW in air ambient; Planar and interdigitated electrode
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2016.01.049

Electrowetting contact angle (CA) change Δcosθ (V) plotted against voltage square V2 for aqueous droplet where concentration varies from 0 to 2M. [Display omitted] •The electrowetting on aqueous droplet with varied electrolyte concentration shows scaling relation to their surface tension.•The EW response on PMMA-Teflon bilayer exhibits low CA hysteresis without oil ambient hence potential dielectric for open microfluidic systems. Electrowetting (EW) allows an executive control on wetting of liquid in several digital micro-fluidic systems driven by both alternating (AC) and direct current (DC) voltages. The electrolytes are inevitable in all fluidic systems that can produce a huge change in conductivity and change in concentration of ions at solid-liquid interface. We report that for an orders of magnitude increase in concentration of KCl electrolyte in a droplet there is minor reduction in DC voltage EW response. The rescaled EW response validates that the result is due to change in surface tension of solution as a function of the electrolyte concentration. Our study demonstrates the efficacy of DC voltage EW in handling aqueous droplets containing a broad range of electrolyte concentration on both planar as well as interdigitated electrode platforms.