Bio-mimetic synthetic cell hydrogel magnetometer

Abstract

We present a bio-inspired hydrogel magnetometer where the cell potential (Voc) between two hydrogels is used to measure an external magnetic field. Ferromagnetic particles located in the hydrogels move in response to the external field and change the Voc (sensitivity ~ 3.7 V T−1). As the field becomes larger than a critical field Bc (~38 mT), these particles puncture the hydrogel boundary shorting out the concentration gradient region and abruptly reducing the Voc (sensitivity ~ 23.5 V T−1). In this regime, the Voc behaves similar to the neuron firing. In subsequent measurement cycles, the particles remain in punctured holes and the sensor behaviour is neuron-like with lower sensitivity (~20 V T−1). Voc also changes as a function of pressure (8 mV kPa−1) and temperature (2 mV K−1). After 4 h, the ionic concentration gradient diminishes in the device, and similar to biological cell fatigue, Voc decreases and can be recharged with many different techniques.