Force Sensor RP-L-110

Force Sensor RP-L-110

20gr/10kg 110mm Resistive Thin Flexible Film Pressure Sensor Analog Output Pressure Force

     The RP-L-110 is a long strip shaped, resistive (FSR) thin film force sensor. It converts pressure in the 20gr - 10kg range into a change of resistance: with no load its resistance is above 10MΩ, with a 20gr press it drops below 200kΩ and it keeps decreasing as the force increases. It is 0.35mm thick and measures approximately 115-118mm x 12-15mm. Thanks to the long sensing surface, pressure is detected anywhere along the strip, not at a single point; it is placed on long surfaces such as a bed edge, a shelf, a robot finger or a bumper.

     The interdigitated silver colored conductive pattern on the black film strip makes more contact under pressure and the resistance of the sensor drops. The strip is flexible and can be bent. The transparent film section at one end has 2 metal terminals; the sensor is read from the analog input (ADC) of a controller board by building a voltage divider with a fixed resistor. The response time is below 10ms. The example curve in the product images shows that the resistance drops non-linearly with force; therefore the sensor is suited to detecting force changes and whether there is pressure, not to precise weighing. The RP-C18.3-ST force sensor with a round 18.3mm sensing surface is a separate product.

Key features:

     Long strip sensing surface: The approximately 115-118mm long strip detects pressure along its whole length, not at one point; suited to long surfaces such as beds, shelves and bumpers.

     20gr - 10kg range: Triggers with a light 20gr touch (resistance drops below 200kΩ), and the resistance keeps falling with pressure up to 10kg.

     Very thin and flexible: The 0.35mm thick film strip can be bent; it can be placed under a surface or on curved parts.

     Fast response: Response time is below 10ms; the moment of pressing and releasing is detected without delay.

     Simple connection: A 2 terminal passive resistor; read from an analog input with a voltage divider using a single fixed resistor.

Features:

• Product type: Long strip type thin film force (pressure) sensor, resistive (FSR)
• Model: RP-L-110
• Measuring range: 20gr - 10kg
• Trigger force: 20gr (resistance drops below 200kΩ when triggered)
• No load resistance: greater than 10MΩ
• Output: Analog, resistance change; resistance decreases as force increases
• Response time: below 10ms
• Activation time: below 0.01s
• Hysteresis: +10% (at 1000gr force)
• Drift: below 5% (24 hours constant load)
• Connection: 2 metal terminals on the transparent film section at the end of the strip
• Construction: Flexible, bendable thin film
• Lifetime: more than 1 million presses
• Operating temperature: -40°C - +85°C
• Material: Thin film strip, interdigitated conductive pattern
• Color: Silver colored pattern on black film, transparent section at the end
• Thickness: 0.35mm
• Dimensions: approximately 115-118mm x 12-15mm (product image 115mm x 15mm, seller value 118mm x 12mm)

Usage information:

• Connect the sensor as a voltage divider with a fixed resistor: one terminal of the sensor goes to the supply (3.3V or 5V), the other to the analog input and through the fixed resistor to GND. The product images include voltage divider, op-amp buffered and relay driving connection diagrams. Choose the fixed resistor value by testing according to the force range you want to measure.
• Place the sensor on a flat and hard base; the pressure should fall on the patterned sensing surface, not on the transparent section at the end. A thin pad can be placed on top of the sensor to spread the pressure over the surface.
• Calibrate the reading with known weights and set a threshold in the program (e.g. person in bed / not in bed).

Applications:

•  Bed occupancy detection: person in bed / not in bed
•  Seat occupancy and sitting detection
•  Grip force detection in robot fingers and grippers
•  Bumper collision detection: robot and vehicle bumpers
•  Shelf product detection: product on the shelf / not on the shelf
•  Shoe insole: step and press detection
•  Door threshold and doormat: passage detection
•  Game controllers and press surfaces
•  Force and touch experiments

Precautions:

•  This sensor is not a load cell: with +10% hysteresis and drift below 5% it does not weigh precisely. For gram accurate weighing use a load cell and a weighing amplifier.
•  The measuring range is 20gr - 10kg; higher force is outside the range. Pointed pressure can damage the film; spread the pressure over the surface.
•  The terminals are attached to the thin film. Do not bend the terminals sharply; keep the soldering iron on them only briefly, or connect with a female jumper wire or connector.
•  The strip is flexible but must not be folded sharply; a folded film can be permanently damaged.
•  The sensor is a passive resistor and does not produce a voltage by itself; a voltage divider circuit is needed to read it.

Package contents:

•  1 pcs Force Sensor RP-L-110
•  Note: Connection wire and fixed resistor are not included in the package.