Pressure Sensing Glove

by rbatzer

The goal of the project is to create a pressure sensing glove to find the force used when blowing glass to help design glass tools. The most important glass blowing tool are jacks, which are pictured below. Jacks are extremely expensive ranging from $250 to $2000 because they are hand made in low volumes.

Thinner blades are helpful when blowing because they have less thermal capacity and cool the glass less when used.  If you know the maximum force being applied to the glass, you can calculated the required blade thickness so they will not bend and therefore make them as small as possible.

Glass blowing is usually done with bare hands and I wanted to the gloves to interfere as little as possible. I ordered very thin liner gloves to house my pressure sensor with an unhemed liner glove on the inside and a second handed glove for the outside.

For the sensor, I chose the to use a cross between the sticky tape and fabric pressure sensors because it could be very thin with  Velostat as the sensor. The graphite infused rubber had a better resistance range, but it was too bulky to integrate into a glove.  I initially tried to make the sensor using iron-on conductive fabric, but I had trouble with the fabric melting through the Velostat as seen below.

The best sensor was single layer Velostat which had higher linearity then multilayer Velostat. I used conductive fabric instead of thread for the Velostat connection because to provides more uniform sensing. The sensor read between 2k and 150k Ohms.

The sensor was then sewn onto the interior glove using non conductive thread to hold the conductive thread down. The inside surface of glove needs to be non-conductive because it will be used with metal tools which would short the sensor.

The sensor output is displayed with four LEDs and uses PWM fading with the AnalogWrite command to give finer resolution. I used the internal 35k Ohm pull up resistor which required me to use only 25% of the voltage reading range.

Arduino Code

The final glove worked well for showing variation in bending or squeezing, but the resistance goes too low from squeezing alone for it to work well with glass blowing. I would need to change the sensor to not be effected by bending to make it more effective.


R_min = 2kOhms

R_max = 150 kOhms

R_pullup = 35 kOhms

V_max = 5V (doesn’t actually matter since LED control is from relative voltage readings, not absolute)

V_out = V_max * R / (R + R_pullup)

V_outmax = 4.05 V

V_outmin = 0.27 V

Once the sensor was installed in the glove, the pressure from just being in the glove lowered the maximum resistance to about 30 kOhms

V_outmax = 2.30 V

I used these ranges to calibrate the values for my LED turn-on.