Description
EEG and ECG recordings are two of the most widely-used diagnostic tests in the medical field. One of the most commonly-used biopotential electrode in EEG and ECG testing is a silver-silver chloride electrode that attaches to the skin via an adhesive gel embedded into the electrode. This electrode transduces brainwave and cardiac signals through the skin very well, however, skin preparation, such as abrasion, and hair removal is needed in order to achieve an acceptable skin connection. This fact makes applying many electrodes to the skin an arduous and painful process. Dry, spiked electrodes are also available, however, they too suffer from drawbacks relating to pain and discomfort during use. The goal of this study was to test and compare two prototype semi-wet electrodes developed in-lab that utilized non-conventional electrode materials. The first prototype utilizes a dry, spiked electrode covered by an electrolyte gel-filled conductive 3D printed polymer cap. The second prototype is a semi-wet polymer fiber core electrode fabricated through a process known as electro spinning. Electrolyte gel is impregnated into the fiber core of this electrode to enhance the amount of ion exchange for biopotential signal transduction resulting from the high surface area the fiber core possesses. A series of trials were performed to analyze the impedance of each electrode over a range of frequencies using an Agilent 4294a impedance analyzer. Impedance analysis measures how well an electrode can transduce a signal with the least amount of noise possible, which in-turn gives the clearest EEG and ECG readings. Impedance and signal transduction have an inverse relationship. The lower the impedance, the clearer the signal. The impedance analysis trials among thirteen different electrode cases revealed that the two hybrid prototype semi-wet electrodes performed better than both the dry electrode and the adhesive electrode on a consistent basis. The first prototype electrode exhibited circuit impedance improvements of approximately 12%, and the second prototype electrode showed improvements as high as 48%. The promising results of the two in-lab developed electrodes have shown strong potential for a new design and material category of biopotential sensors to be further researched and explored.
