We present the design, fabrication, and preliminary testing of a flexible array of sensor switches intended for
applications in wearable electronics and sensor systems. The touch pad sensor arrays feature flexible printed circuit
board (flexible PCB) substrates and/or flexible conductive composite polymer (CCP) structures, resulting in highly
flexible switch arrays. Each switch consists of 4 elements: fascia, target, spacer and a sensor coil. The user presses the
fascia, bringing the target in contact with the sensor coil. Any change in the position of the target changes the coil
inductance due to the generation of eddy currents, which are detected by an electronic circuit and custom software.
Contact between the target and coil also measurably changes the inductance of the coils. Different sizes and geometries
(square, circular, hexagonal and octagonal) of coils in both flexible PCB metal (copper) and CCP were investigated to
determine which couple best with the CCP that forms the target for the inductive coils. We describe techniques for
patterning two-layer inductive coils on flexible PCBs. Using this process, we demonstrate coil trace thicknesses of 200
micrometers. We also present a new low cost microfabrication technique to create inductive flexible coils using
embedded CCP in polydimethylsiloxane (PDMS) as an alternative to flexible PCB metal coils. We further describe an
electronic circuit that accurately measures inductances as low as 500 nH that is used to detect the change in the
inductance of a sensor’s coil when the user presses the target element of the sensor. The inductance for a sensor
composed of CCP square coils and CCP target was measured to be approximately 35 μH before being pressed. When
pressed, the inductance dropped to 3.8 μH, a change which was easily detected.
We present the initial experimental results for manipulating micro-robots featuring permanent magnetic polymer magnets for guided wireless endoscopy applications. The magnetic polymers are fabricated by doping polydimethylsiloxane (PDMS) with permanent isotropic rare earth magnetic powder (MQFP 12-5) with an average particle size of 6 μm. The prepared magnetic nanocomposite polymer (M-NCP) is patterned in the desired shape against a plexiglass mold via soft lithography techniques. It is observed that the fabricated micro-robot magnets have a magnetic field strength of 50 mT and can easily be actuated by applying a field of 8.3 mT (field measured at the capsule’s position) and moved at a rate of 5 inches/second.
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