The overall goal of this procedure is to produce and easy to customize cheap, wireless triggering device as a platform for electromyography research and bespoke assistive devices. Electromyography is usually used as a control input for safe technology. As many pacings require specific solutions that are prohibitively expensive, we developed a cheap, easy to customize device.
Here, we present two bionic clicker system, mark one and mark two that allowed the wearer to change the slide of the presentation by waving their index finger. To begin this procedure, build the bionic mark one as outlined in the text protocol. To begin building the mark two, place a row of three header pins into the muscle center in the positive, negative and signal holes from above.
Next, solder the pins from underneath. Using a pair of pliers, bend the heteropins 90 degrees. If using the abductor indicus muscle as the input, remove the short black reference cable from the muscle sensor.
Then, use a wire cutter to cut the three EMG cables to run from the wrist to the back of the hand. Using a wire stripper, strip one end of each cable. Place the stripped end of the back wire into the R hole, the blue wire into the E hole, and the red wire into the M hole of the muscle sensor.
On the underside, solder the wires into place. After this, cut eight single core multi-thread wires. Place and solder them as outlined in the text protocol.
Place two EMG sensor pads at either end of the abductor indicus muscle. And the third pad on the middle of the back of the hand. Then connect the blue and red sensor cables to the pads above the muscle, and the black cable to the pad on the back of the hand.
Placing of the electrodes on the abductor indicis muscles is the most critical step of the procedure as incorrectly placing the electrodes can cause many false positives and many false negatives in the device. On smaller hands, it may actually be impossible to correctly place the electrodes. To begin testing the EMG output, download all necessary files and set up the microcontroller as outlined in the text protocol.
Next, unplug the computer from the mains. Using a USB cable, plug the microcontroller into the computer. Upload the relevant version of the threshold test to the microcontroller.
Then, open the serial monitor to display the EMG output. Move the hand's index finger from side to side, recording the values displayed. Move the hand around without moving the index finger and record the values displayed.
After this, select a value above what was seen when the hand was moved, but below those scene when the index finger alone was moved. Selecting the threshold value is critical as if it is too low, you'll get many false positives. And if it's too high, you will get many false negatives.
Be aware, the fatiguing of the muscle and movement of the wires can also affect the value of the EC.To begin the test threshold, download, edit and upload the correct code as outlined in the text protocol. Next, move the hand around without moving the index finger. Ensure that nothing is displayed in the serial output.
Then, move the index finger from side to side. To begin, break the copper track on the strip board with a scalpel. And place three 10 kilo ohm resistors on the control board.
Then, place a sliding switch and two push button switches. Solder them on the underside of the board. Using a wire cutter, cut the wires that were previously soldered to the microcontroller such that the wires can run through the mid layer of the microcontroller case to the control board without preventing the case from closing.
After this, place the wires in the control board as outlined in the text protocol, soldering the wires in place. To begin, reassemble the bionic clicker, connecting the header connector from the microcontroller to the muscle sensor. Using a USB cable, connect the microcontroller to the computer.
After downloading the relevant file, edit the code by replacing the placeholder text with the determined threshold trigger value. Then, unplug the USB cable to disconnect the microcontroller from the computer. After connecting the device to a computer, test the clicker with the presentation software by raising the index finger to progress the slides.
To begin mounting the clicker, cut the double sided hook and loop material so that it is 35 meters wide and long enough to wrap around the wrist. Next, slide the hook and loop material through the clips at the bottom of the case. Plug the female header from the microcontroller into the male header pins on the muscle sensor.
Then, clip the electrodes into the EMG cables. In this study, an electromyography based control device is created. Three different ranges are observed while calibrating the device.
The values when the hand is stationary, values for when the hand is moving and values for when the index finger is moved. The threshold value is selected to lie above the hand moving value and below the finger tensing value. A threshold value closer to the moving hand range will experience an increased chance for false positives but a reduction in potential false negatives.
A threshold value closer to the finger tensing range will experience the opposite. The devices are then tested for false positives and negatives when testing the abductor indicus muscle. A false negative is recorded when the device doesn't trigger a slide change when the muscle is tensed.
While a false positive is recorded when a slide changed when no tensing occurred. Neither device had an issue with false positives. While the mark one device experiences no false negatives during the first 45 minutes, the number of false negatives increases rapidly until total device failure between 50 minutes and one hour views.
Thus, while both devices succeed in their stated aims, the mark two is cheaper, more flexible, and more reliable over the course of testing. Whilst attempting this procedure, it's important to correctly place the electrodes and also to be careful when selecting your correct threshold value. Construction of this device can be done in a few hours.
And once finding the threshold is mastered, it can be set up for a new user within minutes. Since its development, this device has been used as the foundation of several student projects as well as the core component in a bespoke patient device. Don't forget that working with the main electricity can be extremely hazardous.
And unplugging devices from the main supply should be made before any contact on the skin on the device it's made.
