Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring.

Lei Ren,Qing Jiang,Lelun Jiang,Chengfeng Pan,Zhipeng Chen,Keyun Chen

doi:10.3390/s16060908

Abstract

A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring.

Highlights

Bioelectricity is a typical physiological phenomenon of humans which can provide important information for diagnostics and treatment
In an EMG signals test, both the micro-needle array electrode (MAE) and Ag/AgCl electrode can trace the change of EMG signals well and reduce the crosstalk [2,5]
In static state recording of ECG signals, signals collected by the MAE agree well with that recorded by typical Ag/AgCl electrodes [2,5,6,7,8,9], while in a dynamic state recording of ECG signals, the MAE can capture more obvious ECG principal features due to the reduction of motion artifacts and a stable contact interface between the MAE and human skin [2,7]

Summary

Introduction

Bioelectricity is a typical physiological phenomenon of humans which can provide important information for diagnostics and treatment. Electrodes, including wet electrodes (typical Ag/AgCl wet electrode) and dry electrodes, can collect and record bioelectric signals [1]. The micro-needle array electrode, as a dry electrode, has attracted more and more attention for physiological electrical signals monitoring (including EII, ECG, EEG, and EMG recording) in recent decades [2]. In the EII test, the MAE presents less variation of contact impedance and better stability due to the significant improvement of the contact interface between the electrode and skin, compared with conventional Ag/AgCl electrodes and metal planar bio-electrodes [3,4]. Sensing performance of the MAE is better in terms of electrode-skin impedance over a long period of recording, as well as a much higher efficiency in preparation of EEG measurements compared with typical Ag/AgCl electrodes [2,10,11]

Methods

Results

Conclusion