Dynamic Contact Angle Variation with Applied Voltage and Droplet Volume in Digital Microfluidics

Abstract

Digital microfluidics allows for controlled droplet movement by applying AC or DC voltages. In this research, we investigated the dynamic contact angle variation of droplets at different voltages and droplet volumes in a digital microfluidics platform. Volumes of 10 µL, 14 µL, and 18 µL were investigated with voltages ranging from 250 V to 400 V. The goal was to investigate how variations in voltage and droplet volume affected the contact angle, specifically by tracking variations in the advancing and receding contact angles. The findings showed that as voltage rises, the contact angle decreases more noticeably in terms of both advancing and receding angles. This shows that higher voltages boost the electrowetting effect and lead to better droplet dispersal and substrate wetting. Furthermore, it was found that across the studied voltage range, the effect of volume on the contact angle was largely consistent. The relation between voltage, volume, and contact angle in electrowetting is better understood from our analysis.

Keywords

• digital microfluidics
• electrowetting
• contact angle
• voltage
• droplet volume