Mechanical engineering capstone project at Rice University. Problem statement was to design a low-cost neonatal incubator for the developing world. Design developed over the course of 2014-2015 with team of senior Mechanical and Bio-engineering students. Project continued on by Rice 360.
Hypothermia contributes to 18-42% of neonatal deaths worldwide (Wariki, 2012). In the developing world, incubators are too costly, unsafe, or ineffective, so hypothermia is one of the leading causes of neonatal death (Lunze, 2013). Hypothermia is a medical condition where the body loses heat faster than it can be produced. A normal body temperature is 37°C, and anything under 35°C is classified as hypothermia (Lunze, 2013). Neonates are at a high risk for hypothermia due to their large surface area, low mass, and low thermal insulation (Fanaroff, 2013).
One method of hypothermia management is the incubator, an enclosed device that controls environmental conditions such as temperature and humidity, reducing convective and evaporative heat loss (Fanaroff, 2013; Lunze, 2013).
Competing products take several forms. The GE Giraffe is the gold standard in the developed world for incubators; however, it costs upwards of $37,000 USD. In low-resource settings, incubators tend to be much simpler and more affordable, but often lack necessary features. The Hot Cot is the current incubator standard in Malawian hospitals. It is equipped with four light bulbs. However, the use of the light bulbs poses a fire hazard if device is not consistently monitored. The Embrace, is a low-cost thermoregulator that relies on heated phase change wax in an insulated sleeping bag. As the device does not use electricity, it is not able to respond to core body temperature and heat is lost when it is opened for feeding.
Based on the problem statement and research on competing products, we designed a low cost incubator with temperature feedback that is proven safe and meets the needs infants and healthcare providers in the developing world. Our Design Criteria were as follows:
- Double-walled wood and acrylic box
- Heating pads in back wall and beneath floor
- Probes read infant and incubator temperature
- System automatically regulates temperature based on the infant probe
- Alarms alert care provider to overheating, under-heating, or power loss
For testing we developed a “Simubaby.” This consisted of an IV bag with circulating warm water. Before testing the system, we tested both the probes and Simubaby. Once these were tested and results were satisfactory, the incubator was tested with 4 different probes. Each experiment was repeated a minimum of 3 times and was done for 5 different target temperatures. Testing showed that the incubator could heat up to target temperature in less than an hour and maintain that temperature.
Incubator is capable of raising and sustaining temperature of hypothermic infants. The current design costs under $250 USD and is capable of in-country manufacturing (based on resources of Malawian partners).
While the design is capable of heating an infant, it’s heat retention is sub-par and only works when there is minimal air circulation. Future designs should focus on optimizing heat retention and increasing air circulation.
The project was handed over to Rice 360. Rice 360 hired an engineer to work full time on continuing the design.
Final Presentation and Materials:
More detailed information on the design process, testing, research, and references can be found in the following documents.