Design,Fabrication And Application Of Dry Electrode Based On Microneedle Array

MEMS has been identified as one of the most promising technologies for the21st Century and has the potential to revolutionize both industrial and consumer products by combining silicon-based microelectronics with micromachining technology. Its techniques and Microsystems-based devices have the potential to dramatically affect of all of our lives and the way we live. World-wide sales of MEMS-based devices are expected to grow from a range of＄13～＄20billion in2003to＄60～＄100billion in2010, Most products have applications in the automotive and IT industries, the next few years is expected to be in medical applications is growing.With the economic and social development, people have more and more attention to the life and health, the field of health care becoming more prosperous. Evaluation of health degree of physiological signals (such as ECG, EEG) plays an important role in medical diagnosis. These signals can be extracted by medical electrodes, so electrodes are indispensable sensors in the medical equipment. In applications, the traditional medical electrodes require conductive paste, the absence of the conductive paste or the evaporation will lead to poor signal to noise ratio. The shortcomings are electrode preparation time is long, continuous use time is short, and damage skin health for long-term use. This paper studies the microelectrode devices are fabricated using MEMS technology. The microelectrodes can precisely control the depth of the piercing, and they have some advantages such as small size, high strength and good biocompatibility. So microelectrode can reduce the damage of piercing position in order to achieve the purpose of painless. The research results are outlined as follows:1. This paper describes a silicon-based dry electrode for recording biopotential. Conventional wet electrode requires skin preparation and electrolytic gel assistant. Dry electrodes can overcome the shortcomings. The surface of the dry electrode is covered by micro-needle array,150μm-250μm high. These micro-needles can pierce the corneum and record biopotential with decreased contact impedance. Microneedles with good uniformity are fabricated by analysis of the corrosion principle and the process steps are stabilized. Dry electrodes of different forms of packaging to suit different test environment are achieved. The electroencephalography (EEG), electrocardiogram (ECG) and electromyogram (EMG) signals are successfully extracted by dry electrodes in vivo experiment.2. The structure, electrical properties, impedance properties of dry electrdoes are improved according to the problems in the production and using process. Peaks microneedle structure greatly reduces the production costs of the dry electrode, Barb-type micro-needle and flexible structure of dry electrodes can prevent dry electrode from leaving the skin in the process of using. The stability of dry electrodes is enhanced through the improvement of electrical properties, baseline drift is reduced during the measurement.3. Microneedle arrays with mcirochannels for transdermal drug delivery are produced. Drug delivery through hollow microneedle arrays can minimizes the shortcomings of the traditional drug delivery methods and has exciting advantages-pain free and tunable release rates. Microneedle arrays and PDMS with channel-chamber package together to form the front of the transdermal drug delivery device to drug delivery.