Monday, March 3, 2014

New Prototype - Cushions and Capacitive Sensors

It was time to move on from the first prototype that used metal lids and a hardboard. In this prototype cushions stitched with conductive fabric were used as the buttons. However, any conductive material can be used here instead of the fabric as the fabric can be costly. Instead of using Makey-Makey as in the previous prototype, Adafruit’s Bluefruit EZ-Key controller has been used to map inputs to keys in a typical computer keyboard.
Adafruit’s Bluefruit EZ-Key controller
Connectivity from EZ-Key to the computer is wireless (Bluetooth) unlike Makey-Makey which allows more flexibility. Two capacitive sensor modules have been deployed to receive inputs from cushions which then were transferred to EZ-Key. It is possible to emulate twelve (12) keys in the keyboard using this setup. My associate supervisor and one of the grad students helped to fix capacitive sensor modules, EZ-KEY and the batteries which power them in to a small plastic box.

Knbos to recieve capacitive inputs

Inside the plastic box
Wires with a pin on one end and a crocodile clip on the other were used to connect cushions with the capacitive sensor modules using knobs on top of the plastic box (see Figure 4). Unlike Makey-Makey, there is no requirement for the person to be grounded as a capacitive sensor can detect the proximity of a moving object and trigger a switch once it reaches a given range within the sensor. A simple GUI based software application is also available to customize key mappings of EZ-Key, if required.

Cushions with conductive fabric connected to the capacitive sensors

 Instructional video for the prototyope
Next step is to take this set-up to the people who I had discussions with and recieve their feedback. Fingers crossed for positive and constructive feedback...

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