Auto-Adjust Pillow

Main and secondary circuit boards.
An under-the-hood look at the pressure sensor and internal pillow chambers.
Close-up view of four-chambered pillow.
Close-up view of velostat and copper fabricated pressure sheets.

Inspiration

Our project, the auto-adjust pillow, is a pillow that addresses the problem of stiff neck, a problem that many people face every night they sleep. Stiff neck occurs because when people sleep, they generally stay in the same position in the middle of the night without moving, and often since these positions are unnatural for the body, they can wake up with a stiff neck. As such, alongside Dr. Nalaka Gooneratne, we wanted to create an embedded device that could address these problems.

What it does

In order to address these problems, our device is going to be able to inflate and deflate at regular intervals in the middle of the night in order to move the patients neck to keep them from having a stiff neck. However, we don’t want to wake individuals due to their head moving, so we plan on using pressure sensors as a measure of sleep state.

How we built it

We first will use pressure sensors to both model the head as well as determine if the individual has moved their head recently (as people generally move their head more in lighter sleep). Finally, we have to build the actual pillow and the inflation mechanisms in order to allow it to inflate and deflate.

Baseline Goals

Working single chamber inflatable pillow that can cycle between air inflation, inaction, and deflation
Working pressure sensor grid that can be used to generate a "heat map" on an LCD screen
Using the pressure sensor values to determine if someone has moved and if they have, not cycling the pillow

Reach Goals

Multi-chamber (4) inflation that can inflate separately and cycle separately
Minimize excessive wiring and produce clean-looking prototype
Seamlessly integrate the sensors into the pillow

Hardware and Mechanical Effort

Build the pressure sensor matrix, using velostat and copper foil
Matrix serves as a series of voltage dividers, where voltage is sent to foil column by column, and then all the rows are measured per column
Used mbed, op-amps, and transistors to select voltages
Used mbed to cycle high to low, op-amps to gain the voltage of this
Connected these to transistors to select between voltage and ground
Used solenoids to inflate pillow
Valves that can let through air or block it based on voltage
Have motor always running, and turn on off solenoid to limit voltage

Software Effort

Analog read the 16 different pressure areas where the copper overlaps
Determine whether the pressure is above, within, or below the threshold
Thickness coefficient for scaling pressure values with respect to inflation percentage
Display a corresponding pressure map for visualization purposes
Cycling the pillow through inflation/deflation via solenoids, except when person has moved past a certain threshold, then stop inflating and deflating for a certain amount of time