The device has several subfunctions:
- The "slave part" will be mechanical. The prosthesis will be designed with CAD software, and it will be able to move (closing the hand into a fist) with the movement of the patient's wrist.
- We will need an Arduino board, to connect all the sensors, read the information and send instructions. This arduino will probably be an Arduino UNO or similar.
- The feedback has different parts:
- Force sensors: There will be one force sensor in each finger, the small Sparkfun force sensor SEN-09673. This sensor will feel whether a finger is touching something or not.
- Vibrating motors: Each force sensor will be connected with one vibrating motor, which will start vibrating softly if its corresponding finger is touching something gently. It will increase the vibration while the pressure in the finger gets higher. The motors will be allocated in the forearm, in different places as it shows in the drawing to enable the user distinguish between fingers. The motor used will be DCM-0006 miniature vibrating motor, from bricogeek.
- Switch: Imagine you are holding something for a long period of time. The vibration might get annoying at some point, so there will be a switch to turn it off if the user wants to. The one I have seen and I think it fits the better is COM-00097, from SparkFun again.
- Temperature sensor: If the user wants to know the temperature of whatever he or she is touching, he will be able. We will install a temperature sensor in the palm of the hand so that whenever the user needs or wants to know the temperature of something, he can. The sensor used will most likely be temperature sensor DS18B20 One-Wire.
- OLED screen display: It will be connected to the temperature sensor in order to show the information received by it. We will place it either in the reverse part of the hand or in the forearm, if there is space enough. The screen I chose is OLED screen 1.3' SH1106 (128x64).
- The power supply will most likely be a rechargeable battery which lasts at least 8 hours. Less would be totally unpractical because the user would not be able to perform long tasks, go outside or work with it. I have found a rechargeable battery, the YSD12900 rechargeable Li-Ion battery. According to the manufacturers, this battery lasts around 29 hours giving supply to 12 leds, so it can work for our project.
- The "skeleton" of the prosthesis will be 3D-printed. There are many useful open-source diagrams around the internet, for example in "enabling the future" or "autofabricantes" that, with some modifications, will suit our project perfectly. The material will probably be plastic, PLA.
- To protect the electrical part of the prosthesis from water or other dangerous things, it will probably have a silicon cover, that will also improve its appearance. This cover will not interfere with the sensors: we will test whether the sensors can read with the cover or not, and if not, we will open the cover around them.