The Tekscan FlexiForce A201-25 is a piezoresistive force sensor capable of measuring up to 25 lbs of force, perpendicular to its sensing plane. In an electrical circuit, this sensor will act as a variable resistor where the change in resistance is inversely proportional to the force applied. The change in resistance can be measured by a simple RC decay circuit, readable by a microcontroller.

Two capacitors and a resistor are included. This will allow you to demonstrate the resistive nature of the sensor with a resistor/capacitor discharge time measurement circuit; no correlations to weight are made. The resistance of the FlexiForce sensor is proportional to weight. The sensor included in the kit has a resolution of about 1.6 lbs. The active sensing area is a .375" diameter circle at the end of the sensor. The conductive leads are easy to connect to a breadboard or through-hole area.

The FlexiForce has an ideal output for A/D conversion; 0V is no force and 4.2V is 25 lbs. In a BASIC Stamp system, the RCTIME command may be used with a LOOKUP table or calibration formula to execute some math to make the output useful.

Force Sensor Kit Features

• Contains FlexiForce Sensor, 220 Ω resistor, 0.1 µF capcitor, and 0.01 µF capacitor
• Measure both static and dynamic forces
• Simple RC circuit interface
• Capable of measuring a total applied force of 25 lbs
• Requires at least 1 PSI on sensing area
• Versatile small size
• Ultra-thin, flexible printed circuit
• Compatible with all Parallax microcontrollers
• Power requirement: 5V DC
• Communication: Variable resistance inversely proportional to applied force
• Sensing area diameter: 0.375 inches (9.53 mm)
• Dimensions: 8.00 × 0.55 × 0.008 inches (203 × 9.53 × 0.208 mm)
• Operating temperature: 15 to 140 °F (-9 to +60 °C)

Download FlexiForce User Manual and BASIC Stamp 2 Code