Medical Implant NFC Embedded System

Abstract

This work is part of the SUPRE (SUbcutaneous PREssure sensor system) research project with the goal of developing health services for patients with dysfunctional urinary bladders. The NANO group at UiO has previously designed and implemented an ASIC SoC (System-on-Chip) using NFC for a blood glucose sensor, while the Polytechnique Montreal has developed an embedded system based on MICS (Medical Implant Communication Service) for a bladder pressure sensor. The system in this work is an alternative to the ASIC design, aiming to achieve similarresultsusinganembeddedsystem. Thegoalistoachieveamoreflexiblesystem with shorter redesign times at the cost of a larger form factor with higher power draw. The design is based around a Xilinx FPGA with an integrated ADC, further increasing flexibility at the cost of size and power. The functionality is implemented primarily using finite state machines, the code was written in VHDL. The goal is to be able to communicate with an NFC tag through SPI and use its on-board memory to temporarily store the pressure sensor readings. The system is idle until a request is initiated externally, for example by an NFC capable mobile phone, after which the analog input is sampled and written back to the tag. A prototype system has been implemented with the AMS 3955 NFC tag and a Basys3 FPGA development board. A custom PCB is the next step for an embedded system, a proposal of which is included in this thesis.