In the development of flexible electrochemical sensors, researchers have discovered a recurring pattern: the device exhibits excellent performance under static conditions, but once it enters real-world scenarios such as skin stretching, joint activity, and tissue peristalsis, the signal begins to drift, sensitivity decreases, or even completely fails.

The problem lies not in the sensor design, but in the interface itself.

Human tissue is an environment that undergoes continuous and dynamic deformation. The stretching rate of the skin during exercise can reach over 30%; The heart beats every minute and second; The gastrointestinal tract is wriggling; The wound tissue is constantly reshaping. Traditional flexible electrochemical devices often adopt the design concept of "integrating rigid electrodes on flexible substrates" - depositing metal thin films or rigid conductive layers on flexible substrates, and then encapsulating them with elastomers. This "hard soft hard" heterogeneous stacking structure performs well in static conditions, but in dynamic deformation, the difference in modulus between different material layers can lead to interface delamination, conductive network fracture, and functional coating detachment. The signal drifts with deformation, not by chance, but by necessity.

2、 From "stretchable" to "stretch resistant": an upgrade of an engineering concept

Stretchable and strain resistant are two different engineering goals. The former focuses on whether the material breaks after stretching; The latter focuses on whether the function is maintained during and after stretching.

In 2026, the team led by Xu Yadong from Peking University and Professor Gao Wei from the California Institute of Technology reported in the journal Science SIRES（Strain-Resilient Intrinsically Stretchable Electrochemical Biointerfaces）， It is a landmark breakthrough in the concept of "stretch resistance". This study proposes for the first time a universal strain resistant intrinsic stretchable electrochemical biological interface, which can maintain high fidelity electrochemical output under up to 300% tensile strain through the synergistic design of material composition, interface structure, and electrochemical transport process.

The core innovation of SIRES lies in the construction of a fully elastic three-layer structure consisting of a strain resistant conductor layer, an electrically adjustable interface layer, and a stretchable functional coating. Unlike traditional designs that integrate rigid electrodes on flexible substrates, SIRES integrates conductive, interface controlled, and functional sensing layers into an elastic system, achieving intrinsic stretchability and interface delamination resistance. This structure enables the electrochemical interface to maintain stable structural integrity and signal output under significant mechanical deformation.

3、 Material System: Multiple Choices from Carbon nanotubes to PEDOT: PSS

The performance of flexible electrochemical electrodes is rooted in the synergy between conductive materials and flexible substrates. The flexible electrochemical electrode independently developed by the company is composed of a flexible substrate and a conductive functional layer in synergy:

• Carbon nanotubes (CNT):High conductivity and good toughness, the conductivity of carbon nanotube composite electrode can reach 20 S/cm, and the attenuation of electrical properties during deformation is minimal. Suitable for flexible lithium battery electrodes and electrochemical sensors.
• Graphene:High carrier mobility, suitable for transparent flexible electrodes and supercapacitors. Single layer graphene films have excellent conductivity and mechanical properties.
• PEDOT:PSS：Conductive polymer with good flexibility, PEDOT: PSS film exhibits excellent performance in epidermal electrophysiological monitoring due to its high conductivity (approximately 3250 S/cm) and stretchability (crack initiation strain>100%). Suitable for brain computer interface electrodes and organic electronics.
• Silver nanowires/nanoparticles:Excellent conductivity, good bending stability, suitable for flexible transparent electrodes.
• MXene：High conductivity, suitable for electrochemical sensing.
• Flexible substrate:Various solutions include polyimide (PI, high temperature resistance, excellent mechanical properties), polyester (PET/PEN, light transmittance ≥ 85%, low cost), elastomers (PDMS, TPU, etc., stretchable, compressible), etc.

4、 Core Performance: What Engineers Should Pay Attention to

5、 Three major application scenarios: from sweat patches to neural interfaces

6、 Advanced Institute Technology's Flexible Electrochemical Electrode Solution

Advanced Institute (Shenzhen) Technology Co., Ltd. was established in 2016 and is a national high-tech enterprise specializing in flexible substrate coating, shielding materials, absorbing materials, and precious metal coating. The flexible electrochemical electrode independently developed by the company is composed of a flexible substrate and a conductive functional layer, which breaks through the defect of traditional rigid electrodes being "hard, brittle, and vulnerable".

The core competencies of the company include:

• Process platform:Various core preparation processes include screen printing (silver paste, carbon paste), vacuum vapor deposition (PVD), electrochemical deposition, and roll to roll hot pressing composite.
• Substrate selection:Various flexible substrates such as PI, PET, PDMS, TPU, etc.
• Conductive functional layer:Carbon nanotubes, graphene PEDOT:PSS、 Various materials such as silver nanowires and MXene.
• Production mode:Roll to roll continuous production, with temperature difference controlled within ± 1 ℃ for electromagnetic heating rollers.
• Key equipment:Electromagnetic heating roller technology realizes roll to roll continuous production, with temperature difference controlled within ± 1 ℃, solving the problems of slow heating and uneven temperature in traditional heating.

7、 Conclusion

The essence of flexible electrochemical electrodes is to establish a stable, low-noise, and biologically friendly molecular signal transduction interface between rigid electronic devices and soft, dynamic biological tissues. From the early "soft package hard" solution of integrating rigid electrodes on flexible substrates, to today's fully elastic and inherently stretchable "all soft" design - the direction of technological evolution is clear: to make electrodes as soft as tissue, stretch like tissue, and not fail during deformation.

The breakthrough of SIRES in maintaining stable electrochemical output under 300% tensile strain marks the transition of flexible electrochemical electrodes from "stretchable" to "tensile resistant". Understanding the physical mechanism of "strain resistant" interface engineering - how strain induced increase in active area and resistance rise form compensation at the circuit level - can reveal the essence of this technological direction more than simply comparing material parameters. In this leap from the laboratory to the real physiological environment, material selection, interface design, and precision machining processes have always been the core variables that determine the upper limit of the performance of flexible electrochemical electrodes.