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  • Review Article
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Soft wearable devices for deep-tissue sensing

Nature Reviews Materials volume 7, pages 850–869 (2022)Cite this article

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Abstract

Wearable devices with skin-like mechanical properties enable continuous monitoring of the human body. However, wearable device design has mainly focused on recording superficial signals from the skin thus far, which can only reveal limited information about health and disease. Deep-tissue signals, for example, electrophysiologic, metabolic, circulatory, thermal and mechanical signals, often have stronger correlation with disease and can predict the onset of symptoms. In this Review, we discuss the engineering of soft wearable devices that can sense signals in deep tissues. We highlight electrical, electromagnetic, thermal and mechanical sensing approaches, investigating sensing mechanisms, device designs, fabrication processes and sensing performance, with a focus on penetration depth and temporal and spatial resolutions in the human body. Finally, we discuss remaining challenges in the field and highlight strategies to further improve penetration depth and specificity, accuracy and system-level integration.

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Fig. 1: Deep-tissue signals that can be sensed by soft wearable devices.
Fig. 2: Electrical probes.
Fig. 3: Electromagnetic probes.
Fig. 4: Thermal probes.
Fig. 5: Vibration probes.
Fig. 6: Ultrasonic probes.

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Acknowledgements

The authors gratefully acknowledge financial support from the National Institutes of Health grants 1R21EB025521-01, 1R21EB027303-01A1 and 3R21EB027303-02S1. The authors thank S. Xiang for valuable discussions and constructive feedback on manuscript preparation, and all authors whose work is reviewed in this article.

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  1. These authors contributed equally: Muyang Lin, Hongjie Hu, Sai Zhou.

Authors and Affiliations

  1. Department of NanoEngineering, University of California San Diego, La Jolla, CA, USA

    Muyang Lin & Sheng Xu

  2. Materials Science and Engineering Program, University of California San Diego, La Jolla, CA, USA

    Hongjie Hu, Sai Zhou & Sheng Xu

  3. Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA, USA

    Sheng Xu

  4. Department of Bioengineering, University of California San Diego, La Jolla, CA, USA

    Sheng Xu

  5. Department of Radiology, University of California San Diego, La Jolla, CA, USA

    Sheng Xu

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M.L., H.H. and S.Z. contributed equally to the literature review, figure design, manuscript writing and discussion of content. S.X. conceived the article. All authors contributed to reviewing and editing the manuscript.

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Lin, M., Hu, H., Zhou, S. et al. Soft wearable devices for deep-tissue sensing. Nat Rev Mater 7, 850–869 (2022). https://doi.org/10.1038/s41578-022-00427-y

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