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Electrochemiluminescent tactile visual synapse enabling in situ health monitoring

Nature Materials volume 24, pages 925–934 (2025)Cite this article

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Abstract

Tactile visual synapses combine the functionality of tactile artificial synapses with the ability to visualize their activity in real time and provide a direct and intuitive visualization of the activity, offering an efficient route for in situ health monitoring. Herein we present a tactile visual synapse that enables in situ monitoring of finger rehabilitation and electrocardiogram analysis. Repetitive finger flexion and various arrhythmias are monitored and visually guided using the developed tactile visual synapse combined with an electrical and optical output feedback algorithm. The tactile visual synapse has the structure of an electrochemical transistor comprising an elastomeric top gate as a tactile receptor and an electrochemiluminescent ion gel as a light-emitting layer stacked on a polymeric semiconductor layer, forming an electrical synaptic channel between source and drain electrodes. The low-power (~34 μW) visualization of the tactile synaptic activity associated with the repetitive motions of fingers and heartbeats enables the development of a convenient and efficient personalized healthcare system.

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Fig. 1: Electrochemiluminescent tactile visual synapse (ECL-TVS).
Fig. 2: Analysis of the operational mechanism in an ECL-TVS.
Fig. 3: Visualization of the tactile synaptic activity in an ECL-TVS.
Fig. 4: Finger rehabilitation monitoring with a wearable ECL-TVS.
Fig. 5: Arrhythmia monitoring system with ECL-TVS.

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Data availability

The data that support the findings of this study or additional data related to this study are available from the corresponding author upon reasonable request. Source data are provided with this paper.

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Acknowledgements

This study was supported by the Creative Materials Discovery Program and the Pioneer Research Centre Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2022M3C1A3081211), by a grant from the National Research Foundation of Korea (NRF) funded by the Korean government (MEST) (RS-2023-00208577), by the Nano & Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (RS-2024-00451891 and RS-2024-00416938), and by the Open Resource Research Program of the Korea Institute of Science and Technology (2E32961). This study was also supported by the National R&D Program administered by the National Research Foundation of Korea (NRF) of the Korea government (Grant NO. RS-2024-00407271, RS-2023-00220077 and RS-2024-00342191) and Korea University Research Grant.

Author information

Author notes

  1. These authors contributed equally: Woojoong Kim, Kyuho Lee, Sanghyeon Choi.

Authors and Affiliations

  1. Department of Materials Science and Engineering, Yonsei University, Seoul, Republic of Korea

    Woojoong Kim, Kyuho Lee, Gwanho Kim, Jebong Ha, Yeeun Kim, Jihye Jang, Ji Hye Oh, HoYeon Kim, Wei Jiang, Jioh Yoo, Taebin Kim, Yeonji Kim & Cheolmin Park

  2. Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA

    Kyuho Lee & Ali Javey

  3. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Kyuho Lee & Ali Javey

  4. Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA, USA

    Sanghyeon Choi

  5. Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea

    Eunje Park, Kwan-Nyeong Kim, Tae-Woo Lee & Keehoon Kang

  6. Research Institute of Advanced Materials, Seoul National University, Seoul, Republic of Korea

    Eunje Park, Tae-Woo Lee & Keehoon Kang

  7. Department and Research Institute of Rehabilitation Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea

    Juntaek Hong & Dong-wook Rha

  8. Department of Chemical and Biological Engineering, Institute of Engineering Research, Interdisciplinary Program in Bioengineering, Soft Foundry, Seoul National University, Seoul, Republic of Korea

    Tae-Woo Lee

  9. SN Display Co., Ltd., Seoul, Republic of Korea

    Tae-Woo Lee

  10. Institute of Applied Physics, Seoul National University, Seoul, Republic of Korea

    Keehoon Kang

  11. KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea

    Gunuk Wang

  12. Department of Integrative Energy Engineering, Korea University, Seoul, Republic of Korea

    Gunuk Wang

  13. Center for Neuromorphic Engineering, Korea Institute of Science and Technology, Seoul, Republic of Korea

    Gunuk Wang

  14. Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, Republic of Korea

    Cheolmin Park

Authors
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Contributions

W.K. and K.L. conceived and designed the experiments. S.C. performed and analysed neural network simulations. E.P. performed the spectroelectrochemical measurement on the P3HT film. G.K. performed the fabrication and demonstration of the ECL-TVS and prepared the figures. J. Ha assisted in some of the experiments, including ion gel preparation and electrical characterization. Yeeun Kim, J.J., J.H.O. and H.K. performed ECL spectra, scanning electron microscopy and X-ray photoelectron spectroscopy measurements and prepared brightness extraction algorithm developments. T.K. and Yeonji Kim assisted with the characterization of ECL ion gel properties. K.-N.K., W.J. and J.Y. prepared a brightness extraction algorithm. A.J. advised on the optical measurements and analyses. J. Hong and D.R. devised a rehabilitation treatment protocol and advised on the relevant content. T.-W.L. and K.K. participated in the discussions regarding the experimental results and provided an interpretation of them. G.W. and C.P. supervised the project, analysed the data and wrote the manuscript. All authors discussed the results and commented on the study.

Corresponding authors

Correspondence to Gunuk Wang or Cheolmin Park.

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The authors declare no competing interests.

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Nature Materials thanks Paschalis Gkoupidenis, Qijun Sun and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Full-colour ECS-TVS.

(a) A plot of the PSC response of an R-ECL-TVS, utilising 20 Vgs pulses sequentially increasing in magnitude. The inset photographs display the light emission of R-ECL-TVS at the increasing number of Vgs pulses. scale bar: 5 mm. (b) Photographs of R, G, and B-ECL-TVS with continuous 15 gate voltage pulses, sequentially increasing in magnitude from −2.2 V to −5 V. Scale bar: 3 mm. (c) Plot of the PSC response of integrated R-, G-, and B- ECL-TVS, utilising 15 gate voltage pulses comprising three sets of five voltage pulses with different voltage magnitudes (−2.7 V for five pulses, −3.3 V for five pulses, and −4.5 V for five pulses) under pressure of 17.20 kPa. (d) Photographs of integrated R-, G-, and B- ECL-TVS at the 1st, 5th, 6th, 10th, 11th, and 15th Vgs pulses. Scale bar: 5 mm.

Source data

Supplementary information

Supplementary Information

Supplementary Tables 1–4, Notes 1–7 and Figs. 1–45.

Supplementary Video 1

Full-colour ECL-TVS operation.

Supplementary Video 2_1

Index-finger exercise monitoring.

Supplementary Video 2_2

Middle-finger exercise monitoring.

Supplementary Video 2_3

Ring-finger exercise monitoring.

Supplementary Video 3

Battery-driven wearable ECL-TVS operation.

Source data

Source Data Fig. 1

Fig. 1e,f.

Source Data Fig. 2

Fig. 2d–k.

Source Data Fig. 3

Fig. 3a–e,h.

Source Data Fig. 4

Fig. 4c,d.

Source Data Fig. 5

Fig. 5c–f,i.

Source Data Extended Data Fig. 1

Extended Data Fig. 1a,c.

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Kim, W., Lee, K., Choi, S. et al. Electrochemiluminescent tactile visual synapse enabling in situ health monitoring. Nat. Mater. 24, 925–934 (2025). https://doi.org/10.1038/s41563-025-02124-x

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