Biomedical Electrode

As a sensor that can effectively convert the ion potential generated by the electrochemical activity of the organism into the electronic potential of the measurement system, biomedical electrodes are widely used in modern clinical testing and biomedical measurements. In recent years, due to the wide application of biomedical electrodes in the fields of electrocardiogram (ECG), electroencephalogram (EEG), electromyogram (EMG), and electrical impedance imaging (EIT), new biomedical electrode structures and efficient and low-cost manufacturing methods have emerged, and manufacturing technology has developed rapidly.

Ag/AgCI Electrode

Ag/AgCl electrode is a biomedical electrode widely used in bioelectric detection technology. It is generally composed of electrode core, Ag/AgCl layer, conductive gel, non-woven fabric and other components. Generally speaking, the Ag/AgCl layer is usually formed by electroplating/electrolysis and other processing techniques.
At present, in the bioelectric signal detection technology, Ag/AgCl electrodes can not only convert ion current into electron current under low current conditions, but also have the advantages of stable electrical signal baseline, strong anti-interference ability, convenient manufacturing and use, low price, and easy production. They are widely used in ECG, EEG and other measurements.
Due to the presence of conductive gel, Ag/AgCl electrodes are prone to dehydration and drying during use, which causes certain changes in the electrical properties of the conductive gel and cannot be used continuously for a long time. Due to the electrical impedance instability of the conductive gel, it is easy to introduce large noise and errors in high-precision experiments, resulting in inaccurate measurement results. At the same time, a certain amount of preparation time is required before the experiment, and the skin needs to be treated to wipe off the stratum corneum on the skin surface as much as possible. In addition, the conductive gel may also cause skin allergic reactions, resulting in redness and swelling. The Ag/AgCl electrode developed by Boyi is a dry electrode with a simple process and easy batch manufacturing, and is promoting related industrial applications.

Microneedle Electrode

Microneedle technology generally refers to an array of microneedle structures formed by chemical etching, reactive plasma etching and other means on the surface of materials such as silicon materials, metals, polymers and glass through micro-manufacturing methods. Generally speaking, the size of a single microneedle structure is usually 30~80um in diameter and more than 100um in length.

The design of microneedle electrodes should take into account the layered structure of the skin. It is necessary to pierce the stratum corneum (generally 10~15um thick) and penetrate the conductive epidermis (generally 50~100um thick) to avoid the high impedance characteristics of the stratum corneum. At the same time, it is not allowed to pierce the dermis (including nerves and blood vessels) to avoid damage to the skin, thereby causing pain and bleeding. Therefore, the penetration depth of the microneedle should be greater than 10~15um and less than 50~100um, so that it can produce a painless electrode-electrolyte interface on the stratum corneum and convert the ion flow caused by active cells into electronic current.

Compared with traditional Ag/AgCl biopotential electrodes, microneedle electrodes often do not require skin preparation and electrolytic gel, are more convenient and reliable to use, have lower impedance, have less electrochemical noise, and are more conducive to long-term measurement.

Flexible substrate electrodes

Flexible substrate electrodes can achieve a high degree of fit with human tissue, especially the skin, and can meet the wear requirements of different parts of the human body. They have a very wide range of applications and have become an important research direction for biomedical surface electrodes. At present, the main materials that can be used for flexible substrate electrodes are polydimethylsiloxane (PDMS), polyimide (PI), polyethylene terephthalate (PET), etc.

In terms of application, the continuous blood glucose monitoring system developed by Boyi uses surface metallization and MEMS patterning processes to achieve 4mm electrode preparation, which is 20% shorter than the 5mm electrodes currently popular on the market. It has both high precision and low cost characteristics, and has the advantages of independent controllable intellectual property rights, simple process, fast response, good stability, and high accuracy.

Insulated dry electrode

The working principle of the insulated dry electrode is different from that of the above electrodes. The insulated dry electrode uses a very thin insulating film to separate the metal electrode from the human body, forming a capacitor between the human body and the metal electrode. The human body and the electrode sheet are the two poles of the capacitor respectively, and the insulating film in the middle is the intermediate medium of the capacitor. The bioelectric signal can be coupled to the input end of the buffer amplifier through this special capacitor to achieve the measurement of biopotential changes. At present, the insulated dry electrode has been widely used in the detection of signals in the fields of aerospace, underwater operations, biomedical measurement, etc.

The continuous expansion of technologies in point-of-care, in-vitro, and laboratory diagnostic device coatings has spurred an escalating demand for the precise application of active and non-active layers during the manufacturing process of these devices. Ultrasonic nozzles possess the unique ability to spray in any direction, enabling them to uniformly coat targeted areas, complex three-dimensional-shaped devices, and even minuscule components while minimizing overspray to a remarkable extent. The coatings generated by ultrasonic spray are characterized by an exceptional level of controllability, affording extremely high transfer efficiencies for the creation of precise thin films from solutions or suspensions. This includes substances such as biopolymers, proteins, EDTA, Heparin, amino acids, enzymes, blood plasma, and preservatives.

Several examples of devices and their corresponding applications that stand to gain significant advantages from ultrasonic spray technology are as follows:

Reagent coatings on microfluidic and microarray devices, commonly known as “lab-on-a-chip” systems, where the precise deposition of reagents is crucial for accurate and rapid diagnostics.
Point-of-care diagnostic and testing kits, which require reliable and consistent coating techniques to ensure the functionality and sensitivity of the assays.
Cell culture vessels, where a uniform coating can enhance cell adhesion and growth, leading to more reproducible experimental results.
Blood glucose monitors, in which the coating of sensing elements with precision is essential for accurate and continuous measurement of glucose levels.
Blood collection and analysis devices, benefiting from the controlled coating to prevent sample contamination and ensure the integrity of the analysis.
Molecular and protein diagnostic kits, relying on the high transfer efficiency of ultrasonic spray to deposit the necessary biomolecules accurately.
Immunoassay kits, which demand a uniform and precise coating to optimize the binding of antigens and antibodies, thereby enhancing the assay’s performance.

About Cheersonic

Cheersonic is the leading developer and manufacturer of ultrasonic coating systems for applying precise, thin film coatings to protect, strengthen or smooth surfaces on parts and components for the microelectronics/electronics, alternative energy, medical and industrial markets, including specialized glass applications in construction and automotive.

Our coating solutions are environmentally-friendly, efficient and highly reliable, and enable dramatic reductions in overspray, savings in raw material, water and energy usage and provide improved process repeatability, transfer efficiency, high uniformity and reduced emissions.

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