NFC-Microcontroller implementation for battery-less sensors based on organic semiconductors

Sustainable and low-cost environmental or biomedical sensors have to fulfil two important requirements. First, they need to enable wireless data transfer, second they should be low-power devices, enabling operation without a battery, driven only by energy harvesting processes. In this scenario, this thesis proposes the implementation of the NXP NHS3152 Near Field Communication (NFC) microchip for the realization of two passive battery-less sensor devices, thought as wearable and low-cost sensors for oxygen concentration and X-ray exposure dose. Regarding the first device, low-power electrochemical oxygen sensors are realized with Organic Electro-Chemical Transistors (OECTs). The sensor design and the readout scheme are optimized to enable battery-less operation with the NHS3152 microchip. A detailed analysis is conducted to investigate the power consumption of OECT-based sensors and to model the dependence on transistor and material parameters. For our application, I demonstrate an energy of 4 µJ to get a readout with a sampling error of 5%. The second sensor device consists of a battery-less NFC dosimeter that exploits a direct X-ray photodiode (Hamamatsu S3590-09) and achieves dose measurements in the range of minimum 2 mGy to a maximum of 80 mGy, over a timeframe of 3 hours. This work shows the possibility of employing the NHS3152 microchip with low-power sensors and it paves the way for realizing devices that are optimized to obtain higher resolutions when using this microchip.