Flexible printed circuit board for biomolecule weight sensing

Abstract 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 µ g, the sensor delivers a resolution of 10 µ g and a limit of detection of 21.16 µ 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.