Final Design

In the field of pediatrics, it has been demonstrated that infants develop better through skin to skin contact with their parents. However, because of the unstable conditions of premature babies, they cannot spend enough time with their parents to gain from the benefits of this experience. Dr. Jae Kim from the University of California San Diego Medical Center was interested in creating a unit to serve as a substitute for the parents. The goal was to develop a unit that could simulate the warmth, skin texture and human tissue comfort that parents provide during skin to skin interaction. In addition, the unit was to be responsive to the baby’s needs through temperature regulation as well as provide a mechanical response to mimic human interaction to the baby’s restlessness. The unit that was built after intensive and research and development is comprised of two main components: mattress and structure.

Mattress

The mattress itself has three layers which can be seen in figure 1 below.

Figure 1: The different layers of the silicone mattress

The top is the simulated skin layer which is special blend of silicone that was cured on top of leather to replicate the texture of skin. The silicone met the sponsor’s request of a simulated skin like feeling, similar thermal conductivity (silicone .22 W/m-K, human skin .37 W/m-K), similar elastic properties and hypoallergenic contact surface.

The middle layer of the mattress acts as a heat reservoir in between the heater layer and the simulated skin. This layer serves to hold the heat and release it slowly. Rice embedded in silicone was chosen after plenty of material testing.

The bottom layer contains silicone rubber heat strips that were embedded in silicone. The silicone rubber heat strips were optimal due to their high power output being able to heat the skin like layer to 37 degrees Celsius in less than ten minutes.

Structure

          The structure that was developed consists of four panels that are driven independently with four stepper motors. These panels are hinged to the screw wall as seen on figure 2 below and attached to a lead screw that is driven by a stepper motor. This configuration allows for upward and downward motion of each panel independently.

Figure 2 CAD of the Motion Platform (left) and 4 panels at different positions (right)

            Toggle switches are used to activate the desired preset positions of the four panels. Furthermore, a force sensing resistor was used to activate random mechanical responses once the baby moves. These responses include rocking, breathing, and a circular wave type motion.

Conclusion

          The unit that was developed met all of the requirements set forth by the sponsor. The mattress can successfully warm up the simulated skin layer to 37°C within ten minutes and can reach higher temperatures if it is called for by a cold preterm baby. The simulated skin layer feels as close to human skin as possible. The structure is able to provide multiple responsive movements that can be used to soothe a restless baby without carrying it. This is important as the preemies in the NICU may not always be able to be picked up due to their condition or fragility.

Figure 3 Picture of final unit