Modular Medical Fridge
Solar-powered thermoelectric fridge for vaccine storage in Lagos hospitals during power outages.
Overview
Hospitals in Lagos, Nigeria face frequent power outages, which causes medicine and vaccine spoilage. Around 30% of vaccines are lost to spoilage from these outages. For Praxis III (ESC204), my team set out to design a more energy efficient fridge that could run on solar power or grid power (when available) to address this issue.
We used a thermoelectric cooling system that theoretically would be more efficient than a traditional fridge if used modularly. The image below is a 1 page description of our prototype.
The Prototype
We prototyped most aspects of our design except for the thermoelectric cooling system (wasn't possible within the constraints of the course). Instead we proxied it with a box containing ice, with a fan that blew the cold air into the fridge. We had a servo motor that dynamically controlled the angle of the fan to blow the cold air towards the hottest region of the box, which was detected by 6 temperature sensors connected to 2 Raspberry Pi Pico Ws. We also had LEDs that lit up the fridge when the lid was opened, with a magnetic sensor that controlled this.
I designed the circuit schematic in Altium before assembly and also integrated it with a web app using the RPPW's for remote monitoring. This allowed us to monitor the temperature sensors in real time, set target temperatures, and toggle modes remotely.
You can see the full CAD of the prototype, the altium schematics, as well as a photo of me and Lawrence assembling the electrical components below.
Results
We were able to achieve a 5°C cooling effect while keeping the temperatures of all 6 sensors within 0.5°C of each other with the fan mechanism.
The final prototype below shows the completed box with all the electronic components.
