Abstract:
Recently, microstructured PDMS based pressure sensors are explored as a potential candidate in biosignal monitoring and electronic-skin applications. Here, we have fabricated capacitive pressure sensors
with micro-pyramidal PDMS dielectric thin films, and studied the influence of surface coverage and
arrangement of these structures on the sensitivity of pressure sensor devices. Pressure sensor with periodically arranged pyramids (surface coverage: 36.7%) exhibited sensitivity of 0.16 kPa-1 in <1 kPa and
0.04 kPa-1 in 0.75-2.5 kPa pressure range, whereas the pressure sensor with diagonally arranged pyramids (surface coverage: 45.2%) exhibited sensitivity of 0.1 kPa-1 in <1 kPa and 0.05 kPa-1 in 0.75-2.5 kPa
pressure range respectively. Despite having large surface coverage, pressure sensor with the diagonally
arranged pyramids exhibited high sensitivity (0.05 kPa-1)in 1-2.5 kPa pressure range than the periodically
arranged pyramids owing to the large displacement and increase in effective permittivity of diagonally
arranged pyramids. Simulation studies on the developed pressure sensor structures using Ansys and
Opera also confirmed the relatively large displacement and C/Co in diagonally arranged pyramids compared to periodically arranged pyramids having slightly low surface coverage. Experimental results and
simulations demonstrate that the sensitivity of these kinds of pressure sensors can also be tuned by
arrangement of pyramids. Also, the developed flexible capacitive pressure sensor is demonstrated for
in-vivo, real-time pulse wave form recording.
