FST 5.08mm Circle Force Sensor (Original)

🧠 What Is It?
A circular Force-Sensitive Resistor (FSR) designed to detect applied force or pressure.
Very small sensing area (5.08 mm diameter) — ideal for precise, localized force detection.
Common in touch, medical, and compact embedded systems.
🔍 Key Features
Ultra-Compact Size: Small circular sensing area (5.08 mm)
Analog Output: Resistance changes with applied force
Flexible & Thin Design: Easy to integrate into tight spaces
Fast Response: Suitable for real-time sensing
High Durability: Supports >1 million actuation cycles
Repeatability: Around ±10%
📊 Technical Specifications
Parameter
Value
Active Area
5.08 mm diameter
Overall Size
~7.62 mm diameter
Thickness
~0.5 mm
Force Range
~0.1 N to 10 N
Actuation Force
~0.1 N
Resistance (No Force)
>10 MΩ
Resistance (With Force)
~1 kΩ – few kΩ
Response Time
<10 ms
Operating Temp.
–30°C to +70°C
Actuation Life
>1 million cycles
⚙️ How It Works
The sensor uses a pressure-sensitive conductive material.
When force is applied, resistance decreases.
This change is converted into voltage using a voltage divider circuit.
A microcontroller reads the voltage via an analog input (ADC).
🔌 Basic Connection
One terminal → VCC (through resistor)
Other terminal → Analog pin + GND
📌 Typical:
Use a 10 kΩ resistor to form a voltage divider.
🧠 Working Behavior
No Force → High Resistance → Low Voltage
More Force → Lower Resistance → Higher Voltage
⚠ Output is non-linear, so calibration is needed for accurate force values.
📌 Applications
Touch sensing (buttons, interfaces)
Medical devices (pressure monitoring)
Gaming controls & joysticks
Robotics (grip/force feedback)
Wearables & smart textiles
Micro-scale pressure detection systems
⚠️ Important Notes
Not for precise weight measurement (use load cell instead)
Small sensing area → requires accurate force placement
Non-linear output → calibration required
Wear over time under repeated heavy pressure
🛠 Summary
Type: Circular Force-Sensitive Resistor (FSR)
Size: 5.08 mm sensing area
Output: Analog (resistance-based)
Best Use: Small-area force/touch detection