The objective of this workshop is to test resistive materials and analyze how they can be used as soft sensors.
First, we measured and recorded resistance values of all materials with a multimeter, and then measured their sensor values with voltage divider circuit and Arduino using “Analog ReadSerial” example; both at rest and when activated.
For Eeonyx StaTex Conductive Fiber and Eeonyx Stretch Sensing Textile we attached alligator clips directly to materials on both sided. For Velostat and Eonyx pressure sensing textile, we assembled contact pads with conductive tapes on either face to allow testing through pressing the resistive material.
Resistance values were read with the multimeter, and sensor analog values (0-1024) were read in the Arduino serial monitor.
- Velostat reduces resistance when pressed or flexed. It’s pressure-sensitive and pressing it makes it highly conductive.
- Eeonyx Pressure Sensing Fabric reduces resistance when pressed
- Eeonyx StaTex Conductive Fiber reduces resistance when squished.
- Eeonyx Stretch Sensing Textile reduces resistance when stretched
Create a Body-Centric Sensor Design, focusing on sensor construction and sensor calibration.
I worked towards designing an interactive smart massage gloves that have the ability to manipulate the ambient of the treatment room. The advantage of the interactive glove is that it gives the therapist the ability to control lighting remotely and simultaneously depending on the patient’s state while under treatment. The therapist can increase or decrease force on specific pressure points on the treated body to reflect muscle tension and therefore produce a relaxing ambient that will calm the patient. I constructed sensors for three fingers: thumb, middle finger and pinky finger. I had plans to give every finger the control of a different feature (such as light, sound, and scent), or of 3 different light locations in the room.
Sensor Design Materials
- Felt material
- Conductive fabric
- Latex gloves
- Conductive thread
- Sewing thread & Needles
- Arduino Uno and Bread board
- 10k ohm fixed resistors
- LED lights (blue, red, yellow)
- Alligator clips and jumper wires
I constructed 3 pressure sensors using Velostat as it’s a force sensitive resistor. the velostat was sandwiched between 2 layers of conductive fabric in the interior and felt in the exterior.
Each sensor was attached to the corresponding finger on the sanitized latex gloves using sewing thread. Then conductive threads ran down along the fingers to be connected to the microcontroller. For the experiment purposes, I attached them from outside, but ideally they should be invisible and embedded inside the glove’s fingertips.
For the time being, I experimented with the thumb to control the intensity of one LED light.
I realized that the sensor is very sensitive and the LED light was always on, even without poking it. So, I had to control the relation between pressure and light intensity and this was by uploading Calibration sketch to Arduino in order to be able to map the minimum sensor value to 0, and the maximum sensor value to 255. I modified the code to allow it to print the sensor values on the serial monitor to watch the changes in relation to light intensity.
Click on the links below to watch videos of the experiment:
From this experiment I learned a great deal with Arduino. I had lots of failures during my experiments. I went through many trials and errors with the sensor assembly, with the circuits and with the code. I learned that Velostat is highly sensitive and conductive, and it’s tricky to control. Also, using latex gloves wasn’t a great idea as they’re delicate and not durable. The process of experimenting with one sensor and one LED light can be duplicated to be tested with the other two sensors and whatever desired ambient feature to be manipulated.
- www.Arduinotogo.com (tutorials)
- www.arduino.cc (tutorials)
- https://cdn-shop.adafruit.com/datasheets/HandcraftingSensors.pdf (product specs)
For next steps, I wish to work more on the aesthetics of the interactive gloves, that is by hiding the sensors inside the gloves and by choosing a more comfortable, durable and visually appealing material. Next I want to learn how to manipulate the lights remotely by researching wireless applications and studying the required software and hardware systems to achieve a successful end result.