mojtaba/amini
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2020·Personal project

Digital glucose meter prototype on Arduino

An Arduino firmware that reads the current of a glucose test strip through an INA219 sensor on I²C, detects the strip and the reaction peak, and converts the reading to mg/dL on a 20×4 LCD — a study prototype, with its mechanical parts designed in CAD.

Code on GitHub ↗Email me →
Role
Embedded developer — firmware, electronics integration, mechanical parts
Period
2020
Context
Arduino · I²C · open source
Technology
Arduino · C++ · INA219 · I²C · LCD · CAD

Hardware

An Arduino board, an INA219 current and voltage sensor on the I²C bus, set to its 16 V / 400 mA calibration for more resolution on small currents, a 20×4 LCD on I²C, and mechanical parts designed in CAD (STEP files in the repository).

Firmware

A state machine: detect the strip from a low but non-zero shunt voltage, ask for blood on the display, wait for the reaction, find the current peak, measure about 4.5 seconds later with millis() timing, convert with a linear calibration to mg/dL and show the result.

What it teaches

Calibration is the real product: temperature, strip batch and reaction time change the reading, and a real device needs clinical validation and certification under the EU IVDR. This was a study prototype, not a medical instrument.

Further reading

Article · Sep 2026
A glucose meter on Arduino: what an embedded prototype teaches

In 2020 I built a digital glucose meter prototype with an Arduino, an INA219 current sensor and an LCD. How it works, where the code was fragile, and why a prototype is not a medical device.