Solar Fridge
Designing a solar-powered refrigerator to store vaccines
Project Background
Mission
More than 1.5 million people die from vaccine-preventable illnesses each year due to limited access to vaccines. Areas with warm climates and limited electricity access are particularly impacted as vaccines need to be kept at a certain temperature range to remain viable.
Therefore, there is a need to develop a sustainable and cost-effective vaccine storage system to maintain vaccine viability during power shut-offs.
Community Partner
During the summer of 2017, our team performed a problem definition trip with our community partners in Rincon Claro – a small village in the Dominican Republic. We learned that the greatest problem they are facing is on-site vaccine storage at their local clinic, making the Solar Fridge a perfect fit. We also visited other communities and concluded vaccine storage is an overarching problem in this region. This trip helped Solar Fridge establish a long-term connection with Dr. Jorge Ramirez, the doctor of Rincon Claro. After making promising progress with our prototype, Solar Fridge plans to travel again to Rincon Claro to implement and receive feedback on our developments.
Design Requirements
User Need
Design Requirement
Design Specification
Vaccines viability is maintained so there is no waste
Maintain vaccine viability during power shut-off
Uniform 2°C and 8°C [1] temperature range for 72+ hour holdover time [2] at maximal 43°C ambient temperature
Fridge must be affordable for all clinics
Cost effectiveness
Manufacturing + shipping costs <$900
Nurses/Doctors need to easily see internal temperatures of fridge
Provide feedback and alerts
Indicator for temperature excursions outside 2°C and 8°C
Displays present, max, min temperatures
Stores past temperatures with 1 measurement/30 min [3]
Follow safe storage conditions for vaccine viability
Storability and organization
Vaccines stores 2-3 inches for unit boundaries [3]
Storage of 50+ vaccines
Separation for 9+ vaccine types [4]
Project History
The origins of Solar Fridge began as a Senior design project in 2008 and transitioned into an interdisciplinary team within M-HEAL a few years later. There have been several iterations of the prototype since the project’s creation and ultimately the team has focused on creating a solar-powered fridge.
By 2022, our Temperature Control and Electrical sub teams each created low-fidelity prototypes based on extensive brainstorming and material research. The Temperature Control sub team focused on constructing a highly insulated and portable cooler while the Electrical sub team made a cooling system using a Peltier Device and PID controller. Each of these subsystems was tested individually and adjusted according to the results.
In winter 2023, Solar Fridge combined these two prototypes and received positive results from testing. After several prototype modifications, repetitive testing, and result analyses, Temperature Control and Electrical sub team members worked together to brainstorm what features our next prototype iteration will include. During this time, our Business sub team developed a new website platform for Solar Fridge and guided the team to the Michigan Business Challenge Finals, a competition for new business proposals.
In fall 2023, we began work on our high-fidelity prototype that we plan to bring during our travel to Rincon Claro this summer. The Temperature Control sub team purchased a new and larger cooler and integrated upgraded insulation while the Electrical sub team began to convert our power source to solar panels. Additionally, the Business sub team began funding and travel planning for the summer.
Leads
References
[1] NSF 456 vaccine refrigerators and freezers testing. UL. (n.d.). Retrieved December 1, 2021, from https://www.ul.com/services/nsf-456-vaccine-refrigerators-and-freezers-testing.
[2] E. Maritz, personal communication, October 3, 2021
[3] Centers for Disease Control and Prevention. (2019, July 11). Vaccines storage and handling toolkit. Centers for Disease Control and Prevention. Retrieved December 1, 2021, from https://www.cdc.gov/vaccines/hcp/admin/storage/toolkit/index.html.
[4] Dr. Jorge Ramirez, personal communication, November 13, 2021
[5] “How to design a peltier module system,” CUI Devices, 02-Apr-2019. [Online]. Available: https://www.cuidevices.com/blog/how-to-design-a-peltier-module-system. [Accessed: 06-Apr-2023].