Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
Inductive Bend Sensor For A Soft Flexible Structure
Technology Category/Market
Category- Robotics & Automation
Industry Classification:
Electronic System & Design Manufacturing (ESDM); Robotics; Sensors
Applications:
Soft robotic fingers or Grippers; Measurement of continuous bending angles in any flexible or deformable structure; Robotic prosthetics or surgical tools to provide feedback on bending or movement; Incorporation into flexible wearables for monitoring movements.
Market report:
The flexible sensors market was estimated at USD 1.51 billion in 2023 and is projected to reach USD 12.15 billion by 2030 with a CAGR of 34.7%
Problem Statement
- Soft robots have the advantage of being compliant with flexible sensors that are essential for safe, precise, and adaptive operations in fragile and variable environments.
- Conventional sensors, including those with resistive, capacitive, optical, and inductive designs, offer features like sensitivity but suffer from issues like hysteresis, complexity, cost, and limited durability.
- Moreover, these sensors face challenges like non-linearity, environmental susceptibility, bulkiness, and mechanical interference which reducing their reliability and practicality for soft robotics.
- There is a need for a planar coil-based inductive bend sensor that resolves existing issues by offering flexibility, linearity, immunity to environmental factors, and easy integration with soft structures.
Technology
- The invention features a planar coil-based inductive bend sensor with three flexible PCB layers, designed to measure bending angles in soft structures with high precision using changes in mutual inductance.
- The sensor uses primary coils on the middle PCB and secondary coils on the top and bottom PCBs, providing a continuum bending angle measurement via relative displacement during bending.
- The sensor PCBs are flexible (0.25–0.35 mm thick) with materials like polyimide or polycarbonate, ensuring durability and integration into soft robotics. Sensitivity is 0.003V/degree with linear ratiometric output.
- Bending creates mutual inductance variations between coils, generating measurable voltage shifts. Configurations include aiding and differential modes for customizable sensing performance.
- Ideal for soft robotic grippers, flexible actuators, and medical devices, the sensor is cost-effective, immune to environmental factors, and provides reproducible, high-accuracy bending angle measurements.
Key Features/Value Proposition
- The sensor employs flexible planar coils stacked in a three-layer PCB assembly. Its design ensures high precision and linearity, with sensitivity of 0.003V/degree, making it suitable for soft robotics and flexible structures.
- The designed sensor’s operation is based on the variation of mutual inductance between the coils. As a result, it is impervious to moisture, dust, and other environmental factors.
- Made from robust, flexible materials like polyimide or polycarbonate (0.25–0.35 mm thickness), it integrates seamlessly with soft structures without interfering with their mechanical behavior, ensuring long-term reliability
- As compared to the existing inductive bend sensors, the proposed sensor uses planar coils which are flexible and can be used for any universal shape of soft robotic fingers or grippers.
- Compared to resistive sensors (prone to hysteresis and non-linearity) or optical sensors (expensive and power-intensive), this sensor is cost-effective, simple to fabricate, highly flexible, and offers linear, reproducible outputs without mechanical interference.
Questions about this Technology?
Contact for Licensing
Research Lab
Prof. Boby George
Prof. Sridharan K
Department of Electrical Engineering
Intellectual Property
- IITM IDF Ref 2652
- IN 552009 Patent Granted
Technology Readiness Level
TRL 4
Technology Validated in Lab