Haptic sensing skin for biomedical applications with soft magnetorheological elastomers

Introduction

Sensorial and tactile information represent the base of all surgical procedures in medicine. The vision sense has been and continues to be developed extensively by the use of micro-cameras, MRI, X-rays, and many others. Nonetheless, in many cases, vision is not enough.

Importance of Touch in Surgery

The touch sense is necessary to identify the stiffness of the underlying organ or tissue and to press more or less to perform a cut, remove a tumor, or even move a catheter inside a curved vein. This stiffness is transmitted to the finger of the surgeon as “pressure-deformation” information. This haptic sense is present naturally in our fingertips.

Challenges with Current Technology

With the recent development of non-invasive techniques, the surgeon operates robotic devices that deliver optical information via a screen but loses all haptic information since his/her fingers are not in direct contact with the organ.

Project Objective

The present project aims at proposing a novel material, a magnetorheological elastomer (MRE) membrane, as a haptic sensor. MREs are soft elastomeric materials comprising magnetic particles, thus being able to deform significantly upon the application of an external magnetic field.

Recent Developments in MREs

Recently, it was shown that by fabricating them in exotic or slender geometries, one can exploit their resulting instabilities to:

1. Shape surfaces
2. Induce programmable swelling and deswelling
3. Create swimming microrobots
4. Develop externally controllable catheters

All those applications use MREs as actuators.

Proposed Sensing Mechanism

By contrast, here, we plan to exploit the reverse operation that of sensing, i.e., induce magnetic field changes via deformation. The principle lies in using the inherent magneto-mechanical coupling to induce readable magnetic fields when the MRE deforms.

Measurement Capabilities

The reading of the fields can then be translated back to a deformation and a force, thus being able to sense soft or stiff objects. The very soft nature of MREs will allow for a very sensitive measurement of forces as low as those felt by touching a soft gel or baby skin.