Co-design of a four-chip NFC system and microfluidic channel for point-of-care electrochemical sensing

Fast, on-site chemical sensing is essential for various applications, including point-of-care analyses that can exploit NFC communications for ease of use with commercial smartphones. Here, we report the layout design of a novel four-chip NFC system integrated with microfluidics for electrochemical sensing, enabling simultaneous analysis of up to four chemical species. Last-generation commercial-off the-shelf NFC boards capable of performing open circuit potentiometry are utilized. However, based on the microfluidic circuit, more liquid samples may be required, hindering measurement accuracy. On the other hand, the arrangement of the commercial-off-the-shelf NFC boards themselves must adapt to the channel’s shape to minimize liquid losses and avoid eventual interferences between the boards. Hence, three layouts of the NFC-microfluidic system are initially considered, and the best one was experimentally selected to optimize i) the amplitude of the read areas, ii) the communication quality, quantified by passive load modulation, and iii) the number of liquid samples required by the microfluidic. The selected system layout is finally validated by quantifying sodium in a standard solution, showing promising results. The resulting system can be used multiple times by simply changing the sensing electrodes and the low-cost, paper-based microfluidic. Ongoing work includes optimizing the microfluidic circuit for blood sensing and testing the system in clinical settings by integrating all the components into an ad-hoc 3D-printed case.