Out With the Old


  1. Not enough skills from class utilized.
  2. Too many non-class skills needed.
  3. Just a little too weird.

Final Project 2.0

My desk is on the floor of a large, open lab space. A lot of times, people will steal my chair when I'm not around. This bugs me a lot, because I'm very particular about my chair settings. So I'm going to build a device that will automatically recognize my biological signature when I'm sitting at my desk. Then, if anybody else tries to use my chair, it sets off a super annoying alarm.


The seat and back cushion will both be made of a flexible composite material. I'll use the spandex fabric with either the Smooth On rubber or dragon skin for the matrix. These materials will be vacume formed onto a 3D model of the chair so that they fit just right. Capacitive and pressure sensors will be placed inside the composite during casting.


I will build pressure sensors using a neoprene foam with copper foil on either side. The copper will be used as a step-response capacitive sensor to give a rough estimate of pressure. I'll use several of these sensors spaced along the seat to recognize the weight profile of a specific user.

The back of the seat will contain several capacitive sensing blocks in order to recognize the capacitive profile of the person in the seat. These will not be pressure sensitive, but instead be tuned to the chemistry of whoever's in the chair.


I will use both peizzo electric buzzers and RGB LEDs to make a big commotion when someone other than me sits in the chair. Hopefully it will be so annoying that they'll get frustrated and leave. These output devices will also have to be embedded into the chair.

Learning and Control

I will mount a button under the armrest of my chair that will trigger the learning phase. The goal will be to have one ATMega168 reading all of the inputs and making decisions about who's sitting in the chair. I'll use an extra ATTiny45 to drive the LEDs and buzzers (possibly 2).

Materials List

  1. One ATMega168 and up to two ATTiny's (44 or 45).
  2. Up to 2 piezzo electric buzzers and 5 RGB LEDs (perhaps 2 DC motors as well).
  3. A small amount of copper foil.
  4. Construction foam in which to mill the chair molds.
  5. Two or three PCBs.
  6. Spandex cloth and a reasonable amount of flexible casting material.