FlexiForce A201 Thin Film Force Sensor for Compact Pressure Measurement The FlexiForce A201 is an ultra-thin resistive force sensor for compact pressure and contact detection. It is useful when a project needs a low-profile sensor under a robot gripper, a test fixture, a soft interface, or a biological force experiment where a bulky load cell would be difficult to install. The sensing element changes resistance as force is applied to the round active area. With a simple voltage divider, the signal can be read by Arduino, ESP32, STM32, Raspberry Pi Pico ADC projects, or an OpenELAB UNO R3 Intermediate Kit V2. For deeper mechanical details, refer to the Tekscan FlexiForce A201 product page. This module is best for relative force trends, contact detection, and project-specific calibrated measurements. It is not a laboratory scale by itself, but it is a strong choice for robotics, HMI controls, production jigs, and thin embedded pressure sensing. Technical Specifications Parameter Value Sensor model FlexiForce A201 class thin film force sensor Sensor type Resistive force sensor Available force ranges 0-1 lb / 0-25 lb / 0-100 lb options Thickness 0.008 in / 0.208 mm Length 8 in / 203 mm Width 0.55 in / 14 mm Sensing area 0.375 in / 9.53 mm diameter Connector 3-pin male square-pin tail connector Linearity error < +/-3% typical after calibration Repeatability < +/-2.5% full scale typical Response time < 5 ms Operating temperature 15 to 140 degF / -9 to 60 degC Development support Arduino analog input, ESP32 ADC, STM32 ADC, Raspberry Pi Pico ADC Board Layout & Label Guide Sensing circle: Apply force to the circular pad only; this is the calibrated active region. Flexible tail: Route the tail without sharp folds and avoid clamping it as the load path. Connector: Use the active sensor leads in a voltage divider; confirm pinout before soldering or crimping. Fixed resistor: Choose the divider resistor to match the expected force range and ADC span. ADC node: Connect the divider midpoint to an analog input on the controller. Mechanical overlay: Use a flat actuator or compliant button cap to distribute load repeatably. Calibration area: Calibrate with known weights in the final fixture rather than in free air. Application Scenarios 1. Robot Gripper Contact Detection Use FlexiForce A201 as a thin contact pad on a robot gripper finger. The sketch reads a voltage divider and reports whether the gripper is touching an object. const int FORCE_PIN = A0; const int CONTACT_THRESHOLD = 260; void setup() { Serial.begin(115200); } void loop() { int raw = analogRead(FORCE_PIN); bool contact = raw > CONTACT_THRESHOLD; Serial.print("force_raw="); Serial.print(raw); Serial.print(" contact="); Serial.println(contact ? "yes" : "no"); delay(100); } 2. Calibrated Pressure Pad After measuring the raw ADC values for no load and a known load, this example maps the reading to a simple 0-100 pressure percentage. const int FORCE_PIN = A0; const int RAW_EMPTY = 40; const int RAW_FULL = 820; void setup() { Serial.begin(115200); } void loop() { int raw = analogRead(FORCE_PIN); int percent = map(raw, RAW_EMPTY, RAW_FULL, 0, 100); percent = constrain(percent, 0, 100); Serial.print("pressure_percent="); Serial.println(percent); delay(200); } 3. Force Event Logger For test fixtures, log only events above a threshold so the serial output stays readable during repeated pressing or loading. const int FORCE_PIN = A0; const int EVENT_THRESHOLD = 500; unsigned long lastEvent = 0; void setup() { Serial.begin(115200); } void loop() { int raw = analogRead(FORCE_PIN); if (raw > EVENT_THRESHOLD && millis() - lastEvent > 500) { Serial.print("force event, raw="); Serial.println(raw); lastEvent = millis(); } delay(20); } Packing List 1 x FlexiForce A201 Thin Film Force Sensor FAQ Q: Can this sensor be used as a precision scale?A: It is best for relative force, contact, and calibrated trend measurement. Use a load cell for certified weighing. Q: Does the output increase linearly with force?A: No. Film force sensors are nonlinear, so project-specific calibration is important. Q: Can I use it with Arduino or ESP32?A: Yes. Read it through a voltage divider using an analog input on an Arduino-compatible board or an OpenELAB Sensor Shield V5 setup. Q: What resistor value should I start with?A: 10 kOhm is a common first test value; increase it for lighter forces and decrease it for heavier force ranges. Q: Can I cut or fold the sensor?A: Do not cut the active area or conductive traces. Avoid sharp folds on the tail. Q: Why do readings drift over time?A: Mounting pressure, sensor hysteresis, temperature, and mechanical creep can all affect readings. Q: How should I mount it?A: Use a flat backing plate and a consistent actuator so force is applied to the sensing area, not the tail. Q: Is it waterproof?A: No. Protect the film and connector from moisture, abrasion, and conductive debris.
