°C-Guard - Medical IoT app for temperature monitoring

The requirement

pfm medical °C-Guard is a digital Bluetooth thermometer for fully automatic observation and documentation of temperatures during storage and transport of vaccines and medications. °C-Guard measures the temperature every 5 minutes and stores it. Via the °C-Guard app, every period can be evaluated using a smartphone or tablet - whether on site or during errand runs.

°C-Guard sensor

The challenge

The challenge was to develop an app that evaluates and visualizes the temperature measurement data. The app had to offer simple and intuitive operation and present the data in a clear dashboard and be developed for iOS and Android. An additional challenge was the communication with the sensor via Bluetooth Low Energy, as the specification provided to us was incomplete and in Chinese. Thus, we first reverse-engineered the protocol. While reverse-engineering, we also noticed some unused optimization opportunities, which we implemented. For example, we were able to speed up the temperature synchronization by a factor of 10.

Chinese BLE specifications

Interesting in terms of programming were the complex algorithms for simultaneous monitoring of multiple sensors via BLE and the extensive configuration options for alarms. Alarms can be triggered at different intervals and at specific times. When an alarm is triggered, it calls a serverless function, which in turn notifies the user in the configured way (email, etc.). This process had to be very stable, as the main use case of the product is in the medical field.

The result

The app was successfully developed and is available in the App Store and Google Play Store and in multiple languages. It is a full-fledged product successfully marketed by pfm medical and used in several countries.

App Store Play Store