The University of Massachusetts Amherst
University of Massachusetts Amherst

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MIE Seminar Series: "Wettability Engineering: Digital Microfluidics by Electrowetting and Electrodewetting"


Friday, September 4, 2020 - 10:00am


Professor Tingyi “Leo” Liu University of Massachusetts, Amherst




Water covers more than 70% of the Earth’s surface, and it is one of the essential sources of life. Although water drops appear to be light and fragile to us, they present a drastically different impression for small-size creatures such as insects. Such difference comes from the liquid surface tension which becomes dominant at smaller scales. Rather than suffering from surface tension, Consequently, a strong force that overcomes the surface tension is required in general to create movements of small drops on a substrate. there are lots of natural species that positively utilize surface tension to change their interactions with water through wettability controls with inspiring hydrophobic and hydrophilic patterns.
In this talk, I will present methods to control droplet movements by electrical signals in artificial devices. I will first show the development history of electrowetting and electrowetting-on-dielectric, which have spurred explosive advancement in both academic research and commercialized applications since the millennium. I will then present our recent advancement of electrodewetting – an unprecedented phenomenon that is opposite to the well-known electrowetting. I will guide you through a journey of how we realize such counterintuitive electrically-induced liquid repellency by wettability engineering at the interface. This new mechanism frees us from hydrophobic coatings and dielectric layers as well as their associated problems, showing improved reliability with extended longevity and strong resilience even to electrolysis, which is the most common failure mode when controlling fluids electrically. To show its generality for digital microfluidics, we have further developed a microfluidic platform to performs all the basic digital microfluidic operations.

Prof. Tingyi “Leo” Liu received his B.E. in Electrical Engineering from Zhejiang University, Hangzhou, China in 2009, M.S. and Ph.D. in Mechanical Engineering from the University of California, Los Angeles (UCLA) in 2011 and 2014, respectively. He joined the University of Massachusetts Amherst in 2018. He is now leading the Interdisciplinary Interface Engineering Laboratory (Inter²EngrLAB). His research focuses on utilizing micro- and nano-fabrication to study diverse interfacial phenomena and to engineer the heterogeneous interfaces for interdisciplinary applications such as soft and stretchable bioelectronics.