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Aravind Vijayaraghavan: Capacitive pressure and touch sensors with suspended graphene-polymer heterostructure membranes

posted 30 Apr 2019, 04:21 by Peter Boggild   [ updated 30 Apr 2019, 07:14 ]
I will present the fabrication and characterization of a suspended graphene/polymer heterostructure membrane spanning a large array of micro-cavities each up to 30 µm in diameter with 100 %  
yield.[1] Such membrannes are then employed in a capacitive pressure sensor covering an area of just 1 mm2, showing reproducible pressure transduction under static and dynamic loading up to pressures of 250 kPa, and in good agreement with calculations. Next, I will demonstrate a novel strained membrane transfer and optimizing the sensor architecture. This enables suspended structures with less than 50 nm of air dielectric gap, giving a pressure sensitivity of 123 aF/Pa per mm2 over a pressure range of 0 to 100 kPa.[2] Lastly, we demonstrate a touch-mode capacitive pressure sensor (TMCPS) incorporating a SU-8 spacer grid structure.[3] This results in a partially suspended membrane configuration, which produces reproducible deflection, even after exposing the membrane to pressures over 10 times the operating range. The device shows a pressure sensitivity of 27.1 ± 0.5 fF/Pa over a pressure range of 0.5 kPa to 8.5 kPa. I will describe our ongoing work to develop a fully transparent, flexible, multi-touch, force-touch capacitive sensor interface, and commercialisation efforts through the new spin-out Atomic Mechanics Ltd. and discuss the future of graphene-based pressure and touch sensors. 
1. Berger, et al. Nanoscale 2016 2. Berger, et al. Nanoscale 2017 3. Berger, et al. 2D Materials 2017

Dr. Aravind Vijayaraghavan is a Reader in Nanomaterials in the School of Materials and the National Graphene Institute at The University of Manchester. He leads the Nano-functional Materials Group (www.nanofunc.com) and his research involves the science and technology of graphene and 2-dimensional materials, particularly for applications in composites, sensors and biotechnology. He was previously a post-doctoral research fellow at Massachusetts Institute of Technology, USA and an Alexander von Humboldt Fellow at Karlsruhe Institute of Technology, Germany. He obtained his MEng (2002) and PhD (2006) from Rensselaer Polytechnic Institute, USA and his BTech (2000) from the Indian Institute of Technology - Madras, India. He has published over 80 papers in international peer reviewed journals and delivered over 60 presentations at international conferences. Dr. Vijayaraghavan is also a leader in science communication and won the 2013 Joshua Phillips Award for Innovation in Science Engagement and was Science Communicator in Residence at the 2013 Manchester Science Festival. He has also been awarded a Royal Society Pairing Scheme Award (2013) and a British Science Association Media Fellowship (2017). He has delivered over 40 public lectures. He is the founder of two spin-out companies, Grafine Ltd. (www.gra-fine.com) and Atomic Mechanics Ltd. (www.atomic-mechanics.com) which commercialise applications of graphene in the fields of composites and sensors respectively.