Oxide Thin-Film Electronics for the Front-End Conditioning of Flexible Magnetic Field Sensors

Unobtrusive magneto-reception can enable innovative applications in diverse scenarios ranging from the interaction of humans with virtual objects to the controlled movement of micro-robots. The required bio-compatible magnetic sensor systems have to be cheap and able to conform to the movement of reconfigurable surfaces and biological tissue, while providing excellent performance. The key to realize such systems is the integration of magnetic sensors with on-site conditioning electronics directly on large-area plastic substrates. In fact, ad-hoc optimized oxide thin-film transistors provide a technology platform which is not affected by mechanical deformation or magnetic fields and can hence be used to boost the performance of magnetic sensor systems through front-end conditioning. Flexible oxide conditioning circuits provide voltage gains close to 50 dB at operation voltages down 1.7 V while bent to radii <4 mm. Fully flexible Co/Cu giant magnetoresistance sensors, Wheatstone bridges and amplifiers can be integrated on a single polymer foil and result in a 50 mu m-thin conformal system with a 25 V/V/kOe sensitivity.