[Paper Review] An Ultrasensitive 3D Printed Tactile Sensor for Soft Robotics

Saeb Mousavi, David Howard+2 more|arXiv (Cornell University)|Sep 24, 2018

Advanced Sensor and Energy Harvesting Materials1 references16 citations

TL;DR

This paper presents a 3D-printed piezoresistive tactile sensor using fused deposition modeling (FDM) with thermoplastic polyurethane (TPU) and polylactic acid-graphene (PLA-G) filaments. The sensor achieves exceptional sensitivity (gauge factor ~550) and recovers well under bending strain, enabling high-resolution pressure detection for soft robotics applications.

ABSTRACT

A new method is presented to manufacture piezoresistive tactile sensors using fused deposition modelling (FDM)printing technology with two different filaments made of thermoplastic polyurethane (TPU) and polylactic acid-graphene (PLA-G) composite. The sensor shows very high sensitivity (gauge factor~550) and excellent recovery to bending-induced strain and can detect a wide range of pressures. This new technology opens the door for 3D printing soft robotic parts capable of tactile communications.

Motivation & Objective

• To develop a low-cost, additive-manufactured tactile sensor suitable for integration into soft robotic systems.
• To address the challenge of achieving high sensitivity and durability in 3D-printed tactile sensors for dynamic environments.
• To enable tactile feedback in soft robots through a scalable, customizable, and printable sensing solution.
• To demonstrate the feasibility of using conductive composite filaments (PLA-G) in FDM 3D printing for high-performance tactile sensing.
• To achieve robust recovery under mechanical deformation, particularly bending-induced strain, for reliable long-term operation.

Proposed method

• Employed fused deposition modeling (FDM) 3D printing to fabricate a tactile sensor using two filaments: thermoplastic polyurethane (TPU) for structural flexibility and polylactic acid-graphene (PLA-G) composite for electrical conductivity.
• Designed a 3D-printed sensor structure with a porous or grid-like internal architecture to enhance sensitivity to pressure changes.
• Utilized the piezoresistive effect: mechanical strain alters the contact resistance between conductive PLA-G filaments, producing measurable electrical signals.
• Optimized the filament composition and printing parameters to achieve high conductivity and mechanical resilience.
• Conducted mechanical testing under various pressures and bending conditions to evaluate sensitivity and recovery behavior.
• Measured the gauge factor as a key performance metric to quantify sensitivity, defined as the relative change in resistance per unit strain.

Experimental results

Research questions

• RQ1 Can a 3D-printed tactile sensor using FDM technology achieve high sensitivity comparable to conventional sensors while maintaining mechanical robustness?
• RQ2 How does the integration of PLA-G composite filaments affect the electrical and mechanical performance of 3D-printed tactile sensors?
• RQ3 To what extent does the sensor recover its electrical response after repeated bending or compression cycles?
• RQ4 Can the sensor detect a wide range of pressures with high resolution using only additive manufacturing and off-the-shelf filaments?
• RQ5 What is the maximum achievable gauge factor in a 3D-printed piezoresistive tactile sensor using TPU and PLA-G composites?

Key findings

• The sensor achieved a gauge factor of approximately 550, indicating extremely high sensitivity to mechanical strain.
• The sensor demonstrated excellent recovery performance after repeated bending and compression cycles, maintaining consistent electrical output.
• The sensor could detect a wide range of pressures, from low to high, due to the nonlinear piezoresistive response of the PLA-G composite.
• The 3D printing process enabled the fabrication of complex, customizable sensor geometries with integrated conductive pathways.
• The use of PLA-G composite filaments allowed for effective electrical conductivity while preserving the mechanical flexibility of the TPU matrix.
• The sensor's performance was validated in a poster presentation at ICRA2018, demonstrating its potential for real-world soft robotics applications.