Whether hydrogels that behave like tissue or algorithms that can tell the difference between a bump in the road or a heart that skips a beat, these devices have the potential to transform healthcare check-ups.
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Advanced Materials Driving Performance
These sensors rest upon a foundation of functional materials that have emerged in recent years.
More and more frequently, advanced hydrogels are the preferred way to bridge electronics and the skin. Their softness, in conjunction with a Young's modulus that ranges from 1 to 100, and their ionic conductivity can all be fine-tuned to work well with biological systems.
Early iterations of hydrogels often dry out, making long-term wear uncomfortable and simultaneously undermining signal quality. Researchers have now developed non-drying zwitterionic hydrogels that can maintain stable water content for over a month, solving problems with dehydration that limited how long they could be worn.
These hydrogel systems also use glycerol and natural moisturizing factors, like sodium pyrrolidone carboxylic acid, to form stable hydrogen bonds that lock in moisture. This allows for continuous biomarker detection without the skin irritation caused by regular dry electrodes.1
Working alongside these soft gels, liquid metal composites have encouraged the tech to take a further step forward.
Gallium-based alloys, which are liquid at room temperature, combine very high electrical conductivity with an ability to stretch several times their original length without breaking. They can be patterned at resolutions down to around 50 micrometres and survive tens of thousands of stretching cycles.
When cracks do appear, they can flow back together and heal. In practice, this makes it possible to draw highly conductive wiring that moves with the body, rather than snapping the first time someone reaches for a shelf or goes for a run.1
Structural Engineering Creates Next-Gen Electrodes
But as with most of today's technology, materials are only half, if not a quarter, of the story. Research has found that the way these materials are arranged on the skin is just as important.
Novel nanomesh systems use electrospun polymer fibers and metallic nanowires to produce electrodes with thicknesses as low as 125 nanometers that maintain electrical stability across 50,000 bending cycles.
These ultrathin structures achieve conformal skin contact without interfering with natural skin movement or perspiration.
Serpentine and kirigami-inspired designs have increased the stretchability of inherently brittle metallic materials. In particular, filamentary snake-like structures have managed to achieve approximately 30 % stretchability, matching the mechanical properties of human skin.2
On top of this, engineers have been building hierarchically structured electrodes using micro-casting and the electrodeposition of gold nanoparticles. These textured surfaces increase the effective contact area with the skin and sharpen signal quality.
Experiments have shown electromyography signals that are roughly 2.5 times clearer and glucose sensors that are about 1.4 times more sensitive than comparable flat electrodes.2
It's the kind of incremental improvement that makes faint muscle signals and subtle metabolic changes easier to pick out from the noise.
Artificial Intelligence Integration
Humans create a lot of data noise, and even the most sophisticated sensor will still see plenty of noise when attached to a moving human. That is where artificial intelligence has started to change what these devices can do.
Instead of treating each data stream in isolation, machine learning models can examine patterns across strain, electrical, optical, and biochemical signals at the same time.
This makes it easier to identify heart rate, change in muscle activity, or a shift in posture. AI systems can also learn what is normal for a particular wearer, instead of relying solely on generic thresholds.3
In addition, stretchable photoplethysmography sensors use special structures to filter out light scattered from superficial skin layers. This technology enables these sensors to focus on deeper blood vessels, significantly reducing motion noise compared to traditional rigid sensors during activities.
Together, this advanced hardware and intelligent software help wearable devices detect subtle changes in health that may indicate early disease progression.3
Long-Term Wearability: Built to Stay On and Stay Working
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For continuous monitoring to move from development to reality, we need these devices to cope with real-life stresses: Sweat, movement, clothes, and even showers.
Long-term wearability is a new central focus of skin-like sensor development, with researchers addressing the practical challenges of continuous monitoring in daily life. The most advanced epidermal electronics have skin-contact impedance below 10 kΩ at 10 Hz while maintaining signal-to-noise ratios more than 20 to 30 decibels during dynamic motion.
These devices showed breathability rates of 51.5 mm/s and water vapor transmission rates of 2,553 grams/m2 per day at 35 degrees Celsius, allowing perspiration to escape while maintaining firm sensor adhesion.2
Durability is being tackled at the molecular level. Supramolecular polymer networks can break and reform bonds, which gives rise to self-healing behaviour. Some of these materials can recover more than 80 % of their original performance after damage and stretch to many times their original length without failing.
These properties ensure that sensors maintain performance over extended wear periods, with devices demonstrating stable electrocardiogram signal acquisition for over 72 hours of continuous immersion in simulated sweat environments without significant noise increase.2
Multimodal Detection Capabilities
As well as looking at durability, "skin-like" electronic sensors can be improved with multimodal sensing capabilities.
When these devices can monitor more than vital signs, they have even further potential.
Modern devices are being equipped with a range of mechanical sensors based on piezoresistive, capacitive, piezoelectric, and triboelectric effects, as well as temperature sensors and biochemical detectors that can measure glucose, lactate, pH, and electrolytes in human sweat.
These systems achieve detection limits in the micromolar range, with sensitivities ranging from 10 to 500 microamperes per mM/cm2, enabling precise tracking of metabolic states and stress indicators.4
Also, the combination of surface-enhanced Raman spectroscopy (SERS) with plasmonic nanostructures embedded in flexible substrates has advanced biochemical detection to the molecular level. This has led to continuous monitoring of vital biomarkers without the need for invasive blood sampling.
Additionally, sophisticated microfluidic systems direct sweat across sensor arrays in a controlled manner, ensuring consistent sample presentation and reliable measurement accuracy during varying activity levels and environmental conditions.4
Click this link to read about biosensors, and the rise of "always-on" biology
The Future of Skin-Like Sensors
These developments reveal a future in which the skin becomes a continuous interface between the body and its data.
Cardiovascular rhythms, breathing patterns, metabolic shifts, and physical activity could all be recorded in the background of daily life, no trip to the nurses required.
For now, skin-like sensors are in a stalemate that can only be resolved with time; mature enough to show clear clinical promise, but still young enough that their ultimate role in everyday care remains undecided.
References and Further Reading
- Xu, J. et al. (2025). On-Skin Epidermal Electronics for Next-Generation Health Management. Nano-Micro Letters, 18, 25. DOI:10.1007/s40820-025-01871-5. https://link.springer.com/article/10.1007/s40820-025-01871-5
- Cheng, J. et al. (2025). Recent Progress in Flexible Wearable Sensors for Real-Time Health Monitoring: Materials, Devices, and System Integration. Micromachines, 16(10). DOI:10.3390/mi16101124. https://www.mdpi.com/2072-666X/16/10/1124
- Yadav, N. et al. (2025). AI-integrated wearable strain sensors: advances in e-skin, robotics, and personalized health monitoring. Nanoscale Advances, 7, 4803-4819. DOI:10.1039/D5NA00574D. https://pubs.rsc.org/en/content/articlelanding/2025/na/d5na00574d
- Wu, S. et al. (2024). Recent advances in multimodal skin-like wearable sensors. Applied Physics Reviews, 11, 041323. DOI:10.1063/5.0217328. https://pubs.aip.org/aip/apr/article-abstract/11/4/041323/3321245/Recent-advances-in-multimodal-skin-like-wearable
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