Paper: An Ultrasensitive 3D Printed Tactile Sensor for Soft Robotics

November 2nd, 2018

An Ultrasensitive 3D Printed Tactile Sensor for Soft Robotics

Recently 3D printed tactile sensors have attracted huge attention due to the numerous advantages of additive manufacturing, such as facile integration of different materials into a complex 3D structure [1-3].

One of the materials that is emerging as a suitable candidate for tactile sensing is graphene. Its superior surface area and high conductivity make it ideal for fabrication of conductive polymer composites.

Unlike soft physical sensors that were developed using thermoset polymers such as PDMS before, tactile sensors made of thermoplastics are considerably simpler to fabricate and print, because they need no post processing to cure the polymer, and they present a stronger bonding with the nano-structured network embedded inside them due to their considerably higher hardness.

Here we present a 3D printed stretchable sensor made of polylactic acid-graphene (PLA-G) conductive polymer composite (CPC) as a piezoresistive sensing material sandwiched between two stretchable thermoplastic polyurethane (TPU) structural layers for acquiring tactile feedback, such as pressure and bending angle.

Upon applying stress, which can be originated from an applied force or bending, the graphene network in the PLA matrix will be modified, leading to substantial resistance changes. The design of sandwiched structure with TPU as the structural layers is to increase stretchability.

In this work a simple Fused Deposition Modelling (FDM) type printer with two different filaments made of TPU and PLA-G composite is used. The sensor performance is tested for detection of bending angle (bending angles of 5 – 20 degrees were detected reversibly) and a wide pressure range (pressure range 292 Pa – 487 kPa could be detected reversibly).

The current sensor shows very high sensitivity and excellent recovery to bending-induced strain (gauge factor ~ 550) and exhibits very stable response to cyclic pressure and bending. Also, it can distinguish between pressure and bending due to its significantly different sensitivity ranges for these two types of stimuli. The ability to integrate structural and sensing materials into one printed part gives several advantages and bypasses some of the limitations of conventional fabrication methods.

This sensor can easily be integrated or attached to soft robotic actuators for acquiring tactile information. Although the 3D printed sensor described here has a simple structure, it demonstrates the potential to create more complex structures and shapes.

Mousavi, Saeb; Howard, David; Wu, Shuying; Wang, Chun. Design and Fabrication of a 3D-Printed, Stretchable and Ultra-Sensitive Tactile Sensor. In: 2018 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference; 26 August 2018; Quebec City, Canada. ASME; 2018. 1-1. 2018-09-16 | Publication type: Conference Material.

Click here to download the paper.

For more information, contact Dr David Howard.