Do you hate a hot pillow? Are you constantly turning your pillow over, all night long? Me too, so I created the Digital Pillow, the world’s first microprocessor controlled, water-cooled pillow — and it works.
I started with a simple proof-of-concept prototype that consisted of two CPU coolers: a simple air-cooled heatsink and a water heat exchanger. I placed a solid-state, semiconductor heat pump called a Peltier junction between the two. I connected a small water pump and ran a coil of tubing through a pillow.
This worked well but had some problems. The pillow was warm at first because the padding insulates, but by morning it was too cold. I realized the only way to solve these problems was to add a microcontroller and redesign the “human interface” — the pillow itself.
The design I ended up with uses an Arduino Micro, 10 temperature sensors, two ultraquiet fans, a speed-controlled water pump, a water flow sensor and an LCD display with keypad. I also upgraded to a 231-watt Peltier junction that generates 788 BTU of cooling power and a 20-amp power supply to power it all. Over-engineering? What’s that?
For the pillow, I used a large rugged water bladder that I stitched to the top of a standard polyfill pillow and attached hose fittings to the cap. The pillow contains six temperature sensors that send the pillow temperature back to the Arduino, which then regulates the Peltier junction power to maintain a constant, comfortable temperature. Other temperature sensors monitor the junction and power supply temperatures and adjust the fan and pump speeds to the minimum settings needed to keep the system running cool. After an initial cool-down cycle that lasts about six minutes, the Digital Pillow runs almost silently.
For more info on this project, check out thedigitalpillow.com.