Preparation of dielectric layers for applications in digital microfluidic thermal switches

Blaž Velkavrh, Urban Tomc, Matej Šadl, Victor Regis, Maja Koblar, Bianka Colarič, Andrej Kitanovski, Hana Uršič

Abstract


In this work, we prepared dielectric layers of three different dielectric materials – Al2O3, polyimide and epoxy-based photopolymer SU-8 and investigated their properties. Aerosol deposition method was used to prepare Al2O3 and polyimide layers, while spin-coating method was used for SU-8 layers. Microstructural analysis revealed dense layers with no anomalies. Temperature- and frequency-independent dielectric permittivity ε’ was observed for Al2O3 and SU-8 layers, while there was slight downside trend with increasing temperature for polyimide layers. According to Young-Lippmann equation of electrowetting on dielectric (EWOD) effect, Al2O3 is considered to be the best due to highest ε’ (∼11) among all three materials, since it requires the lowest voltage to achieve certain droplet contact angle with EWOD.


Keywords


dielectric layers, aerosol deposition method, spin-coating method, microfluidics, thermal switch

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DOI: https://doi.org/10.33180/InfMIDEM2024.305

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