Microengineered Conductive Elastomeric Electrodes for Long-Term Electrophysiological Measurements with Consistent Impedance under Stretch

Abstract

In this research, we develop a micro-engineered conductive elastomeric electrode for measurements of human bio-potentials with the absence of conductive pastes. Mixing the biocompatible polydimethylsiloxane (PDMS) silicone with other biocompatible conductive nano-particles further provides the material with an electrical conductivity. We apply micro-replica mold casting for the micro-structures, which are arrays of micro-pillars embedded between two bulk conductive-PDMS layers. These micro-structures can reduce the micro-structural deformations along the direction of signal transmission; therefore the corresponding electrical impedance under the physical stretch by the movement of the human body can be maintained. Additionally, we conduct experiments to compare the electrical properties between the bulk conductive-PDMS material and the microengineered electrodes under stretch. We also demonstrate the working performance of these micro-engineered electrodes in the acquisition of the 12-lead electrocardiographs (ECG) of a healthy subject. Together, the presented gel-less microengineered electrodes can provide a more convenient and stable bio-potential measurement platform, making tele-medical care more achievable with reduced technical barriers for instrument installation performed by patients/users themselves.

Wearable sensors for monitoring the internal and external workload of the athlete

“…In another study, Hu et al developed a conductive elastomeric electrode devoid of conductive pastes for the measurement of an ECG signal. 111 PDMS was mixed with other biocompatible conductive nanoparticles to improve the electrical conductivity of the substrate. A micro-replica mold casting for the micro-structures was applied to reduce the micro-structural deformations along the direction of signal transmission to maintain the corresponding electrical impedance under the physical stretch by the movement of the human body.…”

Flexible Graphene Electrodes for Prolonged Dynamic ECG Monitoring

“…With the continuing advances in device miniaturization and wireless technologies, wearable on-body ECG devices for long-term use that have been devised to capture and monitor the electrical activity of the heart may help to establish diagnoses in patients, and considerable progress has been made in this field [4,5,6,7]. However, despite advancements in wireless technology and electronics miniaturization, the development of daily ECG monitoring equipment is still limited by the inconvenience of and patient discomfort caused by wet adhesive electrodes [8], which has led to new requirements for high-performance ECG electrodes with biological compatibility. The standard commercial Ag/AgCl electrode used for ECG signal detection relies on a conductive gel to maintain good electrical contact with the skin, but this gel often dries out over time, causing impedance variations and a dramatic reduction in signal quality.…”

Conductive silicone elastomers electrodes processable by screen printing

“…This is due to the larger contact area offered by CB particles, which have a small size. It has already been shown in earlier reports that higher electrical conductivities for PDMS composites were feasible with CB compared to graphite at the same weight concentration 48 . In our case, composites with a CB content of 12 and 22 wt.% exhibited conductivities of 0.12 and 0.54 S/cm, respectively.…”

“…3, Table 1). A further increase of the GNPs content in the composites resulted in a dramatic deterioration of the mechanical properties of the composites and in inhibition of the cross-linking reaction due to the increased viscosity of the composite mixture 48 .

Figure 3Development of conductivity σ and contact resistance ( R c ) of composites consisting of GNPs and CB (left) and development of conductivity and contact resistance of composites with a binary mixture of GNPs and CB at a ratio of (300/n), where n represents the amount of CB used (right).

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