Touch sensitive pads tailored to you
The Enabling Technology project was a collaboration between Sam Jewell and Ross Atkin at the Royal College of Art Helen Hamlyn Centre for Design, the charity Scope and BT. The project looked at ways to narrow the gap between mainstream and assistive technology, to better meet the diverse needs of disabled people. One way to do this is to create pieces of technology that can be tailored to the specific needs of an individual. The researchers created the ‘Tailored Touch’ concept to illustrate this point producing two tailored interfaces, a touchmouse and the Lynstrument.
The touchmouse breaks mouse functions out into individual pads so it can be more easily controlled by someone with poor motor control. Using Electric Paint means the sensor pads can be created in any size or position to meet the needs of the individual user. You can make your own by following this tutorial.
The Lynstrument was created in partnership with musician Lyn Levett to enable her to have better control when performing. Check out the video and the bottom of this page to see the process of creating it- and to hear her amazing music!
Watch the case study here, or scroll down to follow the step-by-step tutorial to create your own Lynstrument using Electric Paint.
Step 2 To begin you will need:
Starting top left, and going clockwise, finally spiralling into the centre
1. 0.1″ (2.54mm) Crimp Connector Housing: 2 Pin – we need 6 of these. Can use a different size, as long as you have enough for 12 pins total.
2. Male Crimp Pins for 0.1″ Housings – again 12 total
3. Multi-core wire
4. Small washers – you guessed it, 12 total
5. USB to USB Micro cable
6. Breadboard. This size or bigger is great
7. Header pins – 3 sets of 12 pins, and 1 set of 6 pins
8. MPR121 chip on a breakout board, again by sparkfun
9. 3.3v Pro Micro – a mini Arduino board made by SparkFun
10. 5x jumper wires – different colours preferred, or single core wire can also be used.
11. 50ml Electric Paint
Step 3 Get the tools
Here are the tools I use, again clockwise from top left:
1. Wire strippers – this type is very cheap and works well for our needs
2. Pliers – toothed nose rather than smooth is best – for crimping the crimp pins. A crimping tool here is even better
3. A “Third hand” tool for soldering (optional, but helps)
4. Paperclips to help soldering the header pins
6. Soldering Iron
7. Soldering iron tip cleaner – again somewhat optional, but helps
Step 4 Solder the header pins
First we’ll solder the header pins. Paperclips can be great for holding them in place while you solder – see photos!
Once you have 3-4 pins soldered in you can take off the paperclips to do the rest.
Solder headers onto both sides of the ProMicro, and both sides of the MPR121 Breakout board.
Step 5 Stick into Breadboard and wire up
Put the two red boards into the breadboard and wire them up exactly as shown.
Simple stuff – Vcc to 3.3V with a red cable, ground to ground with a black one. The others as shown here:
IRQ (on MPR) to A2 (on ProMocro)
SCL (on MPR) to 3 (on ProMicro)
SDA (on MPR) to 2 (on ProMicro)
Leave one row of empty holes on the breadboard next to pins 0 to 11 on the MPR chip – we’ll use these later to attach our touch sensitive pads.
You’re may look more like the second photo shown if you are using jumper wires.
Step 6 Print the stencil, get a scalpel
Get hold of a scalpel or other cutting knife, metal ruler and cutting mat.
Then print the stencil as shown onto a sheet of A3.
This will be used to stencil (paint) the touch sensitive pads for our mouse. The pads with letters on (L R S D) will be mouse buttons – Left click, Right click, Drag and Scroll. The other 8 will be mouse movement directions.
Cut the 8 mouse directions out completely from the paper as shown.
Also cut around 90% of the Mouse buttons – both the letters themselves and the pads, so that they are just held into the paper at the corners, as shown in the last 2 photos on this step.
Step 7 Mount onto card with spray mount
Spray the back of the stencil VERY LIGHTLY with spray mount – just one pass of the paper from far away to begin with. If it doesn’t stick first time, then have another go, but we need to be able to peel the paper off again at the end.
Mount it onto card – we prefer white card of about 1mm thickness, but any card will work. Preferably not black, as the paint will be black!
Then use a knife to cut the final corners around the letters, and peel out the mouse buttons leaving the letters stuck down as shown in the last image on this page.
Step 8 Make holes in the corners of every touch pad
Use a sharp point, as that found on a pair of compasses or a circle cutter, to poke holes through the card in the corner of every touch pad, as shown.
Step 9 Cut the wires for the back
Choose where you want the Breadboard to stick onto the card later – we prefer above the R and S touch pads – and then measure out and cut wires to go between each hole (poked through in the last step) and each socket on the breadboard at the MPR chip.
Leave about 1-2 inches spare at this stage for good measure, depending on how precise / confident you are!
Step 10 Fit the washers and wires
The washers are needed to make a good electrical connection between the painted pad and the wire.
Push the wire through from the back of the cardboard, and then strip with the wire strippers as shown.
Twist the multicore next with fingers, then feed through the washer and twist back on itself.
Pull the wire back through from behind the cardboard so that the washer is right up against the hole in the card. Then push it flat so it sits flat on the card. This is quite important – if it isn’t sitting flat try squeezing the wire flat against the washer with the pliers as shown- – also try pushing the washer down onto the card and then TOWARDS THE HOLE. I have found this helps form a corner in the wire so the washer sits flat.
Tape the wire on the back to keep it tidy, where it will end up – ie where the breadboard will be stuck on the front.
Repeat for the other 11 wires and washers.
Step 11 Paint with Electric Paint!
Get yourself a brush, a cup of water, and some conductive paint.
Lift the washers so you get paint underneath as well as on top – then stick the washers down and be generous with the paint to make them stick down.
When it’s just about dry, lift the paper stencil letter first, with a knife blade if you need, and then take off the whole stencil.
Be careful with mucky fingers – the paint can be very messy, and gets everywhere if you are not careful.
Step 12 Fit the crimp pins - mouse buttons first
First stick the breadboard down with the sticky pad that comes stuck on the back of the breadboard.
Then cut a slot in the cardboard between the pins 0-11 on the MPR chip, and the touch pads. You might need to flip the board over and move the wires before you cut this slot, so you don’t cut into them by accident.
Next feed through your first wires through the slot. Start with the 4 mouse buttons, at each end of the slot as shown.
Cut any excess wire, strip, and then crimp the crimp pins onto the ends of the wires as shown. Finally put the crimped pins into their housings. These will go into pin 0, 1, 10 and 11 on the MPR chip (in the order L, R, S, D)
Step 13 Finish remaining wires
Feed the remaining wires through, crimp and finish them.
Our code is set up to use the wires in this order:
Up-Right on pin 9
Right on pin 8
Down-Right on pin 7
Down on pin 6
Continue clockwise until
Up on pin 2
Step 14 Upload the code
Step 13: Upload the code
Upload the attached arduino code to the arduino.
You’ll need to follow the instructions on the SparkFun website for how to get the drivers etc for the Pro Micro first.
But once you’ve got that working, just hit upload. Remember it’s a 3.3v ProMicro you need to select, not a 5V or a leonardo.