Sensors

The flex sensors were used to detect the degree of flexion in the five digits of the hand. The flex sensors act as a sensing potentiometer that chance in resistance value depending on the degree of curl in the fingers. These flex sensors then output an analog value (0 to 1023) to the Arduino code, which then categorizes the reading into various thresholds correlating to the requirements of each exercise.

The flex sensors are non-polar (they do not have a default positive or negative terminal). This allows them to be soldered to power, analog, and ground through the pull-down resistor with relative ease. To ensure a safe but effective transfer of the signal, solder was tightly wound around the terminals and heat shrink tubing was applied to both terminals for the sensor. Five flex sensors were prepared in this fashion for the circuit.

Force sensors operate in a similar fashion to the flex sensors and were used to detect the variable application of force in two parts of the hand: the thumb as well as the palmar area of the hand. The force sensors also output an analog value to the Arduino code and were wired into the circuit with similar connections and similar heat shrink safety precautions.

The force sensors are also non-polar, but decrease in resistance value when force is applied as opposed to the increase in resistance displayed by an active flex sensor. Because of this difference, the code for threshold values of the force sensor was written to accommodate a default high signal.