Our solution to the problem for Professor Wang’s lab is shown below in the block diagram. We set up a known resistance in series with the sensor, so by reading the voltage dropping across the sensor, we can get the sensor resistance. Since the sensor acts as a variable resistor, its resistance is related to the pressure being applied to it. We then take this analog signal and pass it into an Analog to Digital converter so that we can processes this information in a micro-controller. The micro-controller does the majority of the processing of the data, turning the voltage read into a resistance and the resistance into a pressure reading by use of an entered resistance-pressure curve. It then sends this signal out via bluetooth low energy where it can be read by any number of freely available mobile apps, though we used the BLE Scanner by Bluepixel Technologies in our testing.
Additionally, we wanted our device as small as possible for ease of use, while still maintaining high enough accuracy for use in Professor Wang’s lab. We also wanted the device to be applicable to any similar variable resistance sensor such as for temperature or humidity. In order to for our device to be flexible, we used a potentiometer as the resistor in our voltage divider pictured above. This allows us to alter the resistance of the voltage divider depending on the resistance range of the sensor being used.