Introduction: Touch Sensitive Teaching Aids

About: I'm a Bristol UK based electrical and electronic engineer currently working on a masters at the University of Bristol. I'm also a keen crafter, baker, maker, cooker and eater!

This instructable was made in collaboration with the Bristol Interactions Group at the University of Bristol, it is targeted at both non-technical users and users who would like to develop it further. To make this distinction clear simple instructions are given as well as sections in italics which give more information.

The project was titled Making with makers: A toolkit for multisensory transformation of everyday things

The majority of children who are blind or live with a visual impairment in the UK are educated in mainstream rather than special schools. They usually have teaching assistants (TAs) assigned to them who support them in a variety of ways, including making sure the curriculum is accessible to these children. They often do this either through transcription of textbooks and teaching materials, and/or by making tactile representations of educational content, for example, printing a map using heat-raised paper so that it can be felt and traced through touch. This project sits at the intersection of accessibility, multisensory interaction, maker-culture, physical computing and fabrication.

From this brief a few paths were investigated and eventually we settled on investigating how touch could be used as a trigger to give a richer experience.

Step 1: The Electronics

Parts Needed:

  • 10x 1Mohm Resistors
  • 1x Arduino Uno
  • 1x Small breadboard
  • Wire

The circuit is simply a row of high value resistors, the principle behind how they work can be found here

Connect up the circuit as shown in the pictures above, one side of each of the resistors should be in the power rail of the breadboard which will be connected via a piece of wire to pin 7 of the Arduino. The other side of each resistor should be connected up to the matching pin on the Arduino, starting at pin 13 as the leftmost pin. (The exact order doesn't matter but when using the program make sure the pins you have connected to match up to the relevant pins on the Arduino.

Step 2: Connecting Up

Connecting to the diagram is relatively simple but can be done in a few ways depending on how you have made your diagram. The simplest way is to strip a few cm of the a wire and then using tape to attach it to the object you want to make conductive, then connect the other end of the wire to the relevant pin on your Arduino. If you have access to them crocodile clips are also good for this sort of connection but tend to be less effective on paper based diagrams because they can punch holes in the paper. In one demonstration we used paperclips which have had a length of wire wrapped around them to provide a good connection to the flat paper diagrams. It is possible to solder these wires to make them slightly more robust but it is not necessary unless you plan on using the connectors many times.

A multitude of objects can be used as inputs including fruit, play-doh, plants, foil, copper tape and a selection of other objects. If in doubt try connecting the object to one of the pins and see if the program responds.

Step 3: Using the Software

Linking samples to pins is a relatively simple process, each line within the software refers to the matching pin on the circuit. The program can take any audio file as long as it is in the WAV format. Many sound effects can be found online that are in this format (my preferred source is SoundBible) or you can use software to record your own voice or even sound effects. To do this we used Audacity a free audio recording software available online that can be downloaded here. The software doesn't currently support other file formats but there are many free audio conversion software and even websites where you can upload sound to change the format such as Online Audio Converter. More information about preparing audio files can be found online with a few quick searches.

To load a a sample click change sample on the pin your are interested in, then select your file. The pin and sound are now linked, repeat this for every file you are interested in linking. Once you have this set up how you like you can save the program and reload the sounds at a later date by clicking the save button.

The next step is to hit auto-connect, this should is the arduino is connected automatically select the right USB port for the arduino and the program will be ready to go. If it fails a warning will pop up and simply follow the instructions given.

Step 4: Example Project 1: Touch Sensitive Diagram

The idea behind this diagram is to provide a richer experience for someone who cannot see the layered information a diagram can provide. It would be possible to have drawn this diagram using the conducive ink onto swell paper and using that to produce a raised surface. For our demonstration we used WikiStix to produce the layout.

The first step was to find a diagram to make interactive, the best diagrams are ones that are mainly made of lines and blocky shapes, simply because making these out of WikiStix is trivial. However it is possible to infill large areas with foil or conductive paint. We chose a plant cell which was hand drawn, scanned and then cleaned up on the computer but the original freehand drawing could have been used.

The next step was to make the diagram 3D by building up the Stix into the shapes defined by the drawing. These sticks were then carefully painted on the topside only using conductive ink to preserve the stickiness of the Stix. The conductive paths to the edge of the paper could then be painted on, we used masking tape to keep the lines neat and tidy but it would have been easier to just paint on the lines. The aim was to bring lines to the edge of the page allowing good connections to be made without crossing any other lines. It is possible to peel up Stix and run these lines underneath as shown in our diagrams above.

Once the diagram was made the next step was to connect it up to the circuit built in one of the previous steps. To do this we used wire wrapped around paperclips as connectors. To make these a length of single core wire was cut and stripped at about 3 or 4cm at one end. This wire was then wrapped around the paperclip tight enough that it held a strong connection. The other end was then connected up to the circuit as explained in the electronics section.

We chose to connect up the samples to short recordings of voice that stated which part of the diagram had been touched. This was a very simple example of what could be done but many other diagrams could be made such as maps, paper based instruments

Step 5: Example 2: Interactive Herb Garden

The second example is an interactive herb garden, the original idea was that each herb when touched would say it's name and a short paragraph about its flavours and uses. For our demonstration the plants were set up to play sound effects that matched the feeling of the plants.

The first step was to select the plants, in the UK it is possible to buy potted herbs in most supermarkets relatively inexpensively and so 6 plants were picked. We chose to pick a wide range of herbs that were all different, our store stocked 3 different kinds of basil, although in hindsight we wouldn’t recommend buying chives as when handled they tended to give peoples hands a somewhat garlic-y scent for many hours. After removing the plants from their wrappers they were given a light water, the plants are fine with a reasonable amount of handling but we found if they were recently watered they held up better.

The second step was preparing the electronics, this is relatively simple and is just a repeat of the earlier electronics step. Then long lengths of single core wire were cut and stripped before being pushed into the roots of the plants. This ensures a good connection to the plants and does not harm them in any way, a longer piece of wire pushed into the pots helps to prevent the wires being accidentally pulled out when moving the pots around. The other end of these wires were then connected into the breadboard at the point shown in the photo above.

The final step is to follow the instructions in the software and audio samples steps to set up the sounds to trigger when the plant is touched. The sound effects were found on SoundBible and are all free to distribute and are included in the example program.

Some potential developments of this project could be using more herbs or perhaps plants of different textures instead of smells, it could be used in a larger setup where many plants were on display and could be used to give the scientific name or region. One researcher in our lab suggested building a drum kit which could for example to made of pieces of grass turf cut into different drum shapes and used to trigger drum sound effects.