Flexible printed circuit board for biomolecule weight sensing

This work presents the design, implementation, and characterization of a piezoresistive force sensor integrated into a flexible printed circuit board (FlexPCB). We propose a flexPCB-based MEMS sensing system with graphite as the sensing element and polyimide as the principal substrate material, intended for disposable and low-cost applications. The sensor, which was manufactured using a conventional PCB technique and silk-screen printing, can detect biomolecules attached to nanomagnetic particles with an apparent weight of 0.209 V/V mg-1 when exposed to an applied magnetic field. Within a detection range of 0-80 mu g, the sensor delivers a resolution of 10 mu g and a limit of detection of 21.16 mu g. While the detection limit reflects the weight of the nanomagnetic particle, the actual sensitivity to the biomolecule is substantially higher, allowing the system to detect lower biomolecule quantities effectively.