A robust and low cost ionic liquid based strain
sensor is fabricated for high strain measurements in biomed-
ical applications (up to 40 % and higher). A tubular 5 mm
long silicone microchannel with an inner diameter of 310
μm and an outer diameter of 650 μm is filled with an ionic
liquid. Three ionic liquids have been investigated: 1-butyl-
1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide,
ethylammonium nitrate and cholinium ethanoate. When
the channel is axially stretched, geometrical deformations
change the electrical impedance of the liquid channel. The
sensors display a linear response and low hysteresis with
an average gauge factors of 1.99 for strains up to 40 %.
Additionally, to fix the sensor by surgical stitching to soft
biological tissue, a sensor with tube clamps consisting of
photopatternable SU-8 epoxy-based resin is proposed.