Session: SYMP 1-8: Wearables

Paper Number: 140504

140504 - Non-Woven Conducting Polymer Electrodes for Wearable Sensors 

We present on the integration of multifunctional, conducting polymer electrospun fiber (CPEF) electrodes for use in layered, collocated force and electromyography (EMG) sensors at the human-machine interface. Currently, most human-machine interfaces rely on obtrusive, rigid electrodes not suitable for long-duration use. Further, these interfaces tend to be passive and are not compatible with dynamic shapes and motions of the human body. The envisioned CPEF electrodes will be compliant and conformal, thus facilitating safe, long-duration use, and their sensing capabilities will assist in adapting the user environment and can be used for controlling assistive wearable devices. The apparatus for electrospinning is relatively simple and consists of a high-voltage, DC power supply, a syringe pump, a spinneret and a conductive collector. A DC potential difference is applied between the spinneret and the collector, and a polymer solution flows through the spinneret at a controlled flow rate using a syringe pump. As the solution exits the tip of the spinneret, electrostatic repulsion overcomes the surface tension of the liquid, the solution elongates into a jet, and the solvent evaporates before the fiber deposits on the collector. Fiber morphology and characteristics can be adjusted via the process conditions, such as solvent type, viscosity of the solution, flow rate, spinneret geometry, electric field, ambient conditions, and the collector shape. Electrospinning of conducting polymers produces small diameter, high aspect ratio fibers with charge carrying capability, which enable compliant, flexible, and robust sensors for intelligent, human-machine interfaces. Herein, we will investigate CPEF fabrication process parameters on electrode properties and characterize the electrodes for use in wearable sensors, such as for force and EMG measurements. We will conduct a systematic investigation of blended polymer solutions comprising conducting polymers and typical textile fibers (e.g. nylon, rayon, and polyester). Solutions will be characterized using rheology to determine the viscosity of the solution, which will influence the electrospinning process. Next, we will evaluate the effects of electrospinning process parameters on the fabrication of conductive polymer fibers. Parameters to be varied include solvent concentration, solvent flow rate, spinneret geometry, electric potential, collector distance, collector shape, and duration of electrospinning. We will evaluate the resulting fiber morphology, diameter, length, and conductivity of the electrospun mats. In particular we will consider the uniformity of the CPEF mats in terms of geometry and properties, the effects of various solvents on the resulting electrospun fibers, and the effects of solvent and process parameters on fiber morphology and properties. The electrospun electrodes will be characterized in terms of their sensor performance, electrical conductivity, thermal properties, and mechanical behavior. Characterizations to be performed include differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and electrical resistance/conductivity measurement using a four-point probe. These sensors will allow wearable devices to detect intent and safely augment human actions while simultaneously monitoring wearer states (e.g. stress level).

Presenting Author: Chad Rose Auburn University

Presenting Author Biography: Dr. Chad G. Rose is an Assistant Professor in the Department of Mechanical Engineering at Auburn University. He has a Ph.D. from Rice University. His research interests include robotics, physical human-robot interaction (pHRI), robotic rehabilitation, assistive devices, and wearable robotics.

Authors:

Russell Mailen
Chad Rose