Eco-flex Resistor

by ManuelDSP

(Eco)Flex Resistor

In this project I attempted to fabricate my own silicone rubber flex resistor.

Mixing different concentrations of carbon fibers and graphite powder into a Platunim Cure Silicone Rubber I was able to make a soft resistor that would change its Resistance according to bending and/or pressure applied to it.

Tested concentrations

Carbon fiber:

2.5 phr (parts per hundred rubber) – very conductive

5 phr – Very conductive

Could continue testing lower concentrations of carbon fibers

Graphite :

50 phr – silicone did not set at this concentration

25 phr- silicone did not set at this concentration

12.5 phr- resistor was not conductive enough

Could test a concentration between 25 and 12.5 phr

Photos:

Videos:

Velostat Resistor -

Ecoflex Flex/Pressure Resistor 1 -

Ecoflex Flex/Pressure Resistor 2 -

Arduino Code used:

int sensorPin = A5;
int sensorValue;
int internalLED = 13;
int LED1 = 9;
int LED2 = 10;
int LED3 = 11;
int LED4 = A2;
void setup() {
pinMode(sensorPin, INPUT);
digitalWrite(sensorPin, HIGH); //turns on the internal pull-up resistor
pinMode(internalLED, OUTPUT);
pinMode(LED1, OUTPUT);
pinMode(LED2, OUTPUT);
pinMode(LED3, OUTPUT);
pinMode(LED4, OUTPUT);
digitalWrite(internalLED, HIGH);
Serial.begin(9600);
}
void loop() {
sensorValue=analogRead(sensorPin);
Serial.println(sensorValue);
delay(100);
if (sensorValue < 70)
{
digitalWrite(LED1, HIGH);
if (sensorValue <60)
{
digitalWrite(LED2, HIGH);
if (sensorValue <55)
{
digitalWrite(LED3, HIGH);
if (sensorValue <50)
{
digitalWrite(LED4, HIGH);
}
else
digitalWrite(LED4, LOW);
}
else
{
digitalWrite(LED3, LOW);
digitalWrite(LED4, LOW);
}
}
else
{
digitalWrite(LED2, LOW);
digitalWrite(LED3, LOW);
digitalWrite(LED4, LOW);
}
}
else {
digitalWrite(LED1, LOW);
digitalWrite(LED2, LOW);
digitalWrite(LED3, LOW);
digitalWrite(LED4, LOW);
}
}