Data Sheet

2
The Stretch Sensor is a unique polymer component that changes
resistance when stretched. An un stretched sensor has a nominal
resistance of 1000 ohms per linear inch. As the stretch sensor
is stretched the resistance gradually increases. When the sensor
is stretched 50 % its resistance will approximately double to
2.0 K-ohms per inch.
The stretch sensor is a new way to measure stretch, displacement
and force. The sensor is a flexible cylindrical cord .060-.070
in diameter, with spade or ring electrical terminals at each
end. Recommended operating range is 40-50% elongation for re-
peatable operation.
Making Resistive Measurements
Taking measurements of the stretch sensor uses the same method-
ology as taking resistive measurements of a variable resistor.
The terminal ends of the sensor are connected to a VOM meter set
to measure ohms.
Being a variable resistor one can also employ other methods of
measurements such as placing the stretch sensor in a Wheatstone
Bridge. The output of the bridge is typically the input of an
operational amplifier.
One may use a variety of microcontrollers to read the stretch
sensor. The PIC series of microcontrollers from MicroChip will
be illustrated.
The stretch sensor has a few resistive artifacts.
When stretched into position and released, the resistance may
increase slightly upon release, before decaying to its resting
resistive value.
The decay of the resistive value to its resting value take
place over time. The initial release will typically bring the
resistance value down to approximately +10% of its initial
resting valve. Resistive value continues to decay to its nomi-
nal resting value, see graph 1.