Design of a Low-Cost Baby Incubator
Inspiration
Incubators, which are essential for the management and treatment of preterm babies, are usually very expensive. Their prices range anywhere from $3,000 (18,000 cedis) to $100,000 (600,000 cedis). This is especially worrying because preterm babies account for majority of neonatal deaths worldwide. In 2019 in Ghana, data collected in Cape Coast Teaching Hospital showed that 9% of babies born were preterm. In numbers, this amounted to 271 babies. Of these numbers, only 67.6% of them survived. This is put in context of a country with limited resources yet so many developmental projects to undertake. I was inspired to think up something that would be beneficial not just to my own country, but other countries that may need it. I’m working on the assets and will have it uploaded on my Github soon.
The incubator works simply by circulating air through the system. Fresh air enters through a vent and is filtered with a replaceable bacteria filter. This fresh air is sucked in by a fan through which the air is raised to the desired temperature. After the temperature of the air is raised, the air passes over a container of water and gets humidified. This air passes out of the air outlet, into the main incubation chamber, and back into the air inlet to complete the cycle.
Temperature Control
The heating element is adapted from the same heating element used in kettles. It will be powered by 220VAC (mains) and the temperature will be controlled using a solid state relay which takes information about the temperature of the incubation chamber and switches on or off till it reaches desired levels. The heating element also passively heats the bed of the baby, with the direct heat being stepped down through an insulation layer.
Humidity Control
The humidity is controlled by adjusting the speed of the fan using a motor controller since the humidity of the incubation chamber is directly proportional to the flowrate of the air passing through the water.
Oxygen Control
The oxygen flow will be controlled manually on a valve from the oxygen tank. However, the oxygen concentration sensor will raise an alarm if oxygen levels exceed or fall under desired thresholds.
Electronics Design
ESP32 Microcontroller
The ESP32 is a WiFi enabled microcontroller, which serves as the “brain” for the incubator. It collects data from all the sensors and uses that data to control the speed of the fan and the temperature of the heating element. Because it is WiFi enabled, it can send this data via Web or WLAN to a web or mobile application.
DHT11 Temperature & Humidity Sensor
This is responsible for measuring the temperature and humidity of the incubation chamber.
Transistor
The transistor allows the ESP32 to switch on or off the solid state relay. This is because the relay operates at 5V which is different from the nominal voltage of the 3.3V microcontroller. It is also to prevent the microcontroller from sourcing too much current to the relay.
12V Boost Converter
The 12V boost converter steps up the voltage from 5V to 12V for the fan since the fan has a 12V operating voltage
Brushless Motor Controller
The fan is akin to the one used in the cooling system of desktop computers, thus it requires a special circuit to drive it as well as to control its speed.
MQ5 Gas Sensor
This device is responsible for measuring the oxygen levels in the air passing through the incubation chamber.
Solid State Relay
The solid state relay turns on and off the heating element to control the temperature of the incubation chamber. The choice for a solid state relay is because it is much more reliable than an electromechanical relay.
LCD & Buzzer
To display sensor readings and sound any alerts or warnings.
Mechanical Design
Body 1
Body 1 is a 100cm x 65cm x 50 cm frame going to be fabricated by joining several sections of lasercut 5mm acrylic. The recommended joining technique is gluing.
Body 2.1
Body 2.1 is going to be a 3cm to 4cm thick MDF plywood with jigsaw-cut holes for the air inlet and outlets into the incubation chamber. The MDF plywood is to support the mass of the baby and the bed.
Body 2.2
This is going to be made out of alucobond. With relevant holes for oxygen pipe, fresh air vent, etc. cut either using a jigsaw cutter or a CNC router.
Hardware User Interface for Control Panel
Physical buttons for the hardware interface are to be 3D printed with the casing of the control panel being fabricated from laser-cut acrylic.
Conclusion
This is a tentative post, and will evolve as the project grows. I really have a passion to develop technology that will change people’s lives. However, I currently do not have the means — so I want to make as much design information as I can be available to the world so we can all develop it together. Stay tuned for more projects.
