Figure ) presents a 3D view and a cross-sectional view of the assembled system while (c) and (d) show a close-up view of the measuring system, both in photo and in 3D. The black inner support part serves three main functions: i) to secure the AS7341 board in place, ii) to block external light from reaching the sensor, and iii) to align the sensor with the microfluidic chip. The support features a square aperture (1.8 mm wide) that allows the light from the source to reach the optical sensor after crossing the microfluidic chip. Although placing the sensor closer to the light source would increase the amount of light it receives, the design includes a 10.7 mm clearance to accommodate the tube fittings. This reduction in light is compensated by increasing the measurement integration time. The system is held in place for measurements by a white frame with a mounting bolt. For data acquisition, the sensor is connected to a Raspberry Pi Zero, paired with a 320 × 280 pixel screen (Display HAT Mini, Pimoroni, UK). The sensor is designed to function as a standalone unit, capable of plotting absorbance and measuring the electrolyte's SoC using a pre-loaded calibration without the need of an external computer.