The Spanish National Research Council (CSIC), an agency under the Ministry of Science, Innovation and Universities, is participating in a European project that is developing a new economical and scalable method for manufacturing devices adaptable to any surface using the technology of decals (temporary tattoos). These devices, developed by a CSIC team at the Madrid Institute of Materials Science (ICMM), are ultra-thin and can be integrated onto surfaces with any kind of topography, such as skin, textiles, and biological tissues, so they can be used to monitor patient health, for example. The new method has just been published in the journal ACS Nano.

Conformable devices "must adapt perfectly to soft, curved, and dynamically deformable surfaces, while maintaining reliable electrical performance," explains Andrés Castellanos-Gómez, a CSIC researcher at the ICMM and the project leader in Spain. These characteristics make manufacturing this type of device a complex challenge: "While two-dimensional semiconductors are promising materials for this type of application, their integration into conformable electronic systems remains complex," adds Yigit Sozen, also a CSIC researcher at the ICMM and one of the lead authors of this work.

Both researchers explain that currently, most tests of conformable electronics based on 2D semiconductor materials are limited to small-scale laboratory fabrication methods. "In fact, one of the main obstacles is the lack of scalable fabrication strategies that simultaneously offer high electronic quality, low cost, and large-scale processability," notes Sozen.

In this context, Castellanos-Gómez points out that temporary tattoo transfer papers have become "attractive substrates for conformable electronics" since they allow the transfer of ultra-thin films onto curved and rough surfaces such as skin, glass, or plastics.

Using this technology, this research team is overcoming current limitations by combining their own high-throughput 'roll-to-roll' mechanical exfoliation technology of van der Waals materials (two-dimensional materials) with ultra-thin substrates for the transfer of temporary tattoos and water-transfer decals. In this way, they have managed to establish a scalable route toward conformable electronics based on 2D semiconductor materials.

Their workflow begins with their dry exfoliation strategy, a technology with two facing cylinders that they have already patented. Once they obtain large-area films composed of interconnected 2D semiconductor flakes with electronic properties, these films are integrated onto ultra-thin transferable platforms using the same commercial decal substrates. All of this enables the fabrication of conformable photodetectors, thermistors, and transistors that can be transferred directly onto rough and curved surfaces such as skin, synthetic leather, and plant leaves.

"By combining scalable production of van der Waals semiconductor materials with simple ultra-adaptable transfer strategies, this work extends tattoo-based electronics beyond organic systems and establishes a practical platform for high-performance wearable and bio-interfaced devices," states Sozen.

The reason behind mechanical exfoliation

In this work, the team demonstrates that combining high-throughput mechanical exfoliation (known as 'roll-to-roll') of molybdenum disulfide (MoS₂) with commercial water-transfer decal paper provides a low-cost and scalable route for the fabrication of conformable devices.

Castellanos-Gómez works with this method of obtaining two-dimensional materials, since other existing techniques currently have significant drawbacks. On the one hand, liquid-phase exfoliation followed by printing leaves a solvent residue. It exhibits poor connectivity between flakes, as well as limited film uniformity, "which often compromises electronic performance." On the other hand, films produced by chemical vapor deposition (CVD) require very expensive infrastructure and involve highly complex transfer processes. In contrast, mechanical exfoliation with cylinders provides dry, interconnected films that can be easily integrated onto ultra-thin, transferable platforms.

"By leveraging this materials platform together with simple decal-based transfer strategies, we fabricate ultra-conformable devices that operate reliably on rough and flexible surfaces. The resulting decal-based photodetectors, thermistors, and transistors exhibit high responsivity, high temperature coefficients of resistance, and high-mobility, low-voltage transistor operation," concludes Castellanos-Gómez. 

Reference:

Yigit Sozen*, Esteban Zamora-Amo, Juan J. Riquelme, Andres Castellanos-Gomez*. Scalable Conformal Electronics Based on Roll-to-Roll Exfoliated van der Waals Semiconductors. ACS Nano. DOI: https://doi.org/10.1021/acsnano.6c04448 

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Tuesday, July 7, 2026 - 13:20