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12. Skin Electronics

Research

E-skin is a cutting-edge wearable technology inspired by human and biological skin. These systems combine high sensitivity, multifunctionality, and adaptability, enabling real-time interaction with the body and environment. Recent developments focus on mimicking tactile sensing, with features like color change and stretchability, supporting applications in health monitoring, motion tracking, and prosthetics Next generation

  • Skin Electronics: Next-Generation Device Platform for Virtual and Augmented Realitys - Next generation

Electronic skin (e-skin) is a rapidly evolving area in wearable technology, inspired by the sensory and structural features of human and biological skin. These bioinspired systems offer multifunctionality, high sensitivity, and strong adaptability, enabling real-time interaction with users and environments. Advances include sensors that mimic human tactile functions, as well as smart features like color change, stretchability, and reversible adhesion. E-skins are being developed for applications such as motion tracking, health monitoring, and prosthetics. Despite ongoing challenges, these innovations are paving the way for the next generation of skin-integrated electronics.

  • Mimicking Human and Biological Skins for Multifunctional Skin Electronics - Mimicking Human

Everyday materials known for their affordability, accessibility, and ease of use, have long served as tools for writing and drawing. However, their potential in the realm of skin-interfaced health technologies remains underexplored. This study presents a range of wearable electronic devices created using pencil-drawn graphite on office paper, including sensors for biophysical parameters (such as temperature and biopotentials), sweat analysis (pH, uric acid, glucose), thermal stimulators, and energy harvesters that utilize ambient humidity. In these devices, graphite serves as both conductive paths and electrodes, while standard paper functions as a flexible substrate. These systems enable continuous, real-time monitoring of physiological signals—such as skin temperature, ECG, EMG, brain waves, heart and respiratory rates, and sweat biomarkers—with signal quality comparable to traditional methods. Additionally, humidity-powered generators are developed by forming oxygen group gradients across the paper, producing up to 480 mV of voltage for more than two hours. A self-powered iontophoretic patch is also demonstrated for transdermal drug delivery. Further applications include pencil–paper-based antennas, functional 2D/3D circuits with LEDs and batteries, reconfigurable modules, and eco-friendly devices using water-soluble, biodegradable paper substrates.

Pencil on skin electronics * Pencil–paper on-skin electronics - Pencil–paper on-skin electronics

Future electronics must become more compatible with the human body to support advanced health monitoring, medical therapies, and seamless human–machine interaction. Unlike conventional electronics, which are rigid and non-degradable, the human body is soft, stretchable, self-healing, and biodegradable. This contrast has led to the development of “skin-inspired electronics,” a new class of devices made from materials that mimic the properties of skin.

These electronics integrate stretchability for comfort and mechanical resilience, self-healing for durability, and biodegradability to minimize environmental impact and avoid secondary surgeries in medical applications. Recent advances include intrinsically stretchable polymers and composites engineered for both flexibility and high electrical performance. These materials have enabled the creation of stretchable sensors, displays, and transistor arrays. Self-healing capabilities are being achieved through dynamic molecular interactions, while biodegradable components are being developed using bio-based and degradable polymers. Together, these innovations represent a new direction in electronics, better aligned with the dynamic and organic nature of the human body.

Skin inspired electonics * Pencil–paper on-skin electronics - Skin inspired electonics


Process and workflow

Hydrogel to skin electronics experimentation
Considering the potential of biomaterials in the field of skin electronics, the electrical conductivity of 10% w/v carboxymethyl cellulose (CMC) hydrogels was evaluated. This property was also evaluated in 10% w/v CMC hydrogels with 20% w/v NaCl and 10% w/v CMC hydrogels with 2% w/v LiCl.

Fig. 1 Carboxymethyl cellulose (CMC 10% w/v solution)

Fig. 2 NaCl

Fig. 3 LiCl

25 g of the solutions were placed in 10 cm Petri dishes and left to dry for 24 hours in a laminar flow chamber.

Fig. 4 Hydrogels in a laminar flow chamber (CMC 20% w/v solution)

Skin electronics tattoo-sticker nfc tag
An NFC sensor and a temporary metallic tattoo that adheres to the skin were used. The sensor adheres to the desired skin area by simply peeling off the cover, leaving the adhesive part exposed.

The temporary tattoo was fixed and adhered to the skin according to the provider's instructions.

Fig. 5 Carboxymethyl cellulose (CMC 20% w/v solution)

The sensor LED is activated when the NFC signal is detected.

Skin electronics simple system

Fig. 6 Squematic


Fig. 7 Skin electronics button (velostat)


Fig. 8 Skin electronics button decorated with gold leaf

Results

Hydrogel to skin electronics experimentation

Fig. 9 Hydrogel_CMC

Fig. 10 Hydrogel CMC-NaCl

Fig. 11 hydrogels CMC.LiCl

Skin electronics tattoo-sticker nfc tag

Fig. 12 Tattoo- sticker nfc

Skin electronics simple system

Fig. 13 Tattoo- sticker nfc

Video

Hydrogel to skin electronics experimentation

Skin electronics tattoo-sticker nfc tag

Conclusion

The results obtained from CMC hydrogels demonstrate that they are not capable of conducting electricity. As can be seen in the video, CMC-NaCl hydrogels do have the ability to conduct electricity. However, these hydrogels contain a high percentage of NaCl, resulting in opaque materials with many crystals, making them brittle. CMC-LiCl hydrogels conduct electricity; they are not a saturated solution. This CMC-LiCl mixture promises to be an alternative for continuing to explore biocompatible biomaterials capable of conducting electricity.

Electronic skin (e-skin) technologies are paving the way for the next generation of highly wearable, multifunctional, and adaptive electronic systems. Inspired by the remarkable sensory and structural features of human and biological skins, researchers have developed innovative bioinspired materials that offer precise tactile sensing, enhanced flexibility, and seamless integration with the human body. The incorporation of features such as visual response to stimuli, reversible adhesion, and camouflage has expanded the potential of e-skins beyond conventional applications. These systems are now playing a significant role in areas like motion tracking, health monitoring, and advanced prosthetics. While current advancements are promising, challenges related to long-term durability, scalability, and biocompatibility remain. Continued interdisciplinary efforts in material science, bioengineering, and design will be crucial for fully realizing the potential of e-skin technologies in real-world applications.

References & Inspiration