In rehabilitation assessment and motor function monitoring, surface electromyography (sEMG) is one of the most commonly used non-invasive detection tools - by using electrodes attached to the skin surface, weak electrical activity generated during skeletal muscle contraction can be recorded, providing objective data for the assessment of neuromuscular function.

However, therapists and engineers face a recurring dilemma: although the traditional Ag/AgCl wet electrode has low contact impedance and reliable signal quality, it relies on conductive gel. The gel will dry up over time, leading to signal deterioration, and long-term adhesion may cause skin irritation and even inflammation. The electrode cannot be reused and is prone to detachment during movement - in scenarios that require long-term continuous monitoring, the limitations of wet electrodes are particularly prominent.

2、 Engineering challenges for sEMG acquisition: impedance, noise, and motion artifacts

The essence of sEMG signal is the projection of muscle action potential on the skin surface - with amplitudes ranging from microvolts to millivolts, the signal is extremely weak. Collecting this weak signal from the surface of the skin poses a triple engineering challenge:

Core proposition:The core question that flexible non-invasive electrodes need to answer is - how to make the electrodes soft, stretchable, and wearable like skin while maintaining low impedance and high signal-to-noise ratio?

3、 Material system: diverse choices from metal to carbon based

The performance of flexible sEMG electrodes is rooted in the synergy between conductive materials and flexible substrates. The current mainstream material system covers three categories: metals, carbon based materials, and conductive polymers

4、 Structural Design: Mechanical Adaptation from Two to Three Dimensions

The stretchability of the material itself is limited. Structural design is equally crucial for maintaining stable contact between the electrode and the skin during dynamic motion.

5、 Key Performance: What Engineers Should Pay Attention to

6、 Application scenarios: From rehabilitation assessment to human-computer interaction

7、 From Materials to Systems: Advanced Institute Technology's Flexible Electrode Solution

Advanced Institute (Shenzhen) Technology Co., Ltd. (referred to as "Advanced Institute Technology") was established in 2016, headquartered in Bao'an District, Shenzhen. It is a national high-tech enterprise specializing in shielding materials, insulation materials, thermal conductivity materials, and precious metal coatings. The company has independently built a magnetron sputtering and vacuum evaporation production line, using roll to roll continuous production technology, which can achieve precise deposition of metal layers on various flexible film surfaces such as PI, PET, PEEK, LCP, etc. The substrate width can reach 350mm, and the ultimate vacuum degree can reach 1 × 10 ⁻⁴ Pa.

In response to the specific requirements of flexible non-invasive electrodes for surface electromyography acquisition, Advanced Institute Technology provides the following core capabilities:

8、 Conclusion

The essence of surface electromyography collection using flexible non-invasive electrodes is to establish a stable, low-noise, and biologically friendly signal channel between rigid electronic devices and soft biological tissues. It uses a flexible substrate to match the mechanical properties of the skin, a low impedance conductive layer to ensure signal quality, and structural design to "guide" motion strain from the functional layer - the three work together to answer a core engineering question: how to make electronic devices as soft as skin while also understanding muscle language.

From rehabilitation assessment to prosthetic control, from motion monitoring to human-computer interaction - flexible sEMG electrodes are bringing the collection of electromyographic signals from hospitals to homes, from static to dynamic, and from "sticking up" to "growing up". In this technological evolution, material selection, structural design, and precision coating processes have always been the core variables that determine the upper limit of electrode performance.