Liquid Droplet for Motion Sensing

In this letter, inspired by the structure of a utricle/ balloon within the vestibular system as a body balance organ, a device with a droplet of ionic liquid (IL) for motion sensing is designed and fabricated. The droplet of IL serves as the inertial mass, and active carbon is used as the electrodes. The fabricated motion-sensing device with a droplet of IL (~15 μL) in a micro-square-groove (2 mm × 3 mm × 5 mm) and two coaxial parallel active-carbon electrodes can successfully detect low-frequency acceleration, even without signal amplification. A voltage signal with a magnitude of millivolts is detected across the system load R
_L
. In the frequency range of 2.5 to 11.75 Hz, the resonant frequency of the device is measured as 7.13Hz, and the peak output voltage across R
_L
is 10.2 mV. This motion-sensing system is promising for future stretchable electronic systems with bionic micro-fluidic sub-structures.