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Vol. 18 (2026)

Deep Learning-Assisted Organogel Pressure Sensor for Alphabet Recognition and Bio-Mechanical Motion Monitoring

https://doi.org/10.1007/s40820-025-01912-z
Kusum Sharma
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, Republic of Korea
Kousik Bhunia
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, Republic of Korea
Subhajit Chatterjee
Department of Computer Engineering, Jeju National University, Jeju‑Si 63243, Republic of Korea
Muthukumar Perumalsamy
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, Republic of Korea
Anandhan Ayyappan Saj
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, Republic of Korea
Theophilus Bhatti
Interdisciplinary Graduate Program in Advanced Convergence Technology & Science, Jeju National University, Jeju, Republic of Korea
Yung‑Cheol Byun
Department of Computer Engineering, Major of Electronic Engineering, Jeju National University, Institute of Information Science & Technology, Jeju 63243, Republic of Korea
Sang‑Jae Kim
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, Republic of Korea

Corresponding Author: Sang‑Jae Kim

kimsangj@jejunu.ac.kr

Nano-Micro Letters, Vol. 18 (2026), Article Number: 63

Abstract

Wearable sensors integrated with deep learning techniques have the potential to revolutionize seamless human–machine interfaces for real-time health monitoring, clinical diagnosis, and robotic applications. Nevertheless, it remains a critical challenge to simultaneously achieve desirable mechanical and electrical performance along with biocompatibility, adhesion, self-healing, and environmental robustness with excellent sensing metrics. Herein, we report a multifunctional, anti–freezing, self-adhesive, and self-healable organogel pressure sensor composed of cobalt nanoparticle encapsulated nitrogen-doped carbon nanotubes (CoN CNT) embedded in a polyvinyl alcohol–gelatin (PVA/GLE) matrix. Fabricated using a binary solvent system of water and ethylene glycol (EG), the CoN CNT/PVA/GLE organogel exhibits excellent flexibility, biocompatibility, and temperature tolerance with remarkable environmental stability. Electrochemical impedance spectroscopy confirms near-stable performance across a broad humidity range (40%-95% RH). Freeze-tolerant conductivity under sub-zero conditions (−20 °C) is attributed to the synergistic role of CoN CNT and EG, preserving mobility and network integrity. The CoN CNT/PVA/GLE organogel sensor exhibits high sensitivity of 5.75 kPa−1 in the detection range from 0 to 20 kPa, ideal for subtle biomechanical motion detection. A smart human–machine interface for English letter recognition using deep learning achieved 98% accuracy. The organogel sensor utility was extended to detect human gestures like finger bending, wrist motion, and throat vibration during speech.


Highlights:
1 We rationally designed a robust, biocompatible CoN CNT/PVA/GLE organogel with self-healing, anti-freezing, and self-adhesive properties for wearable sensing applications.
2 Incorporation of CoN CNT enables high-performance, stable pressure sensing for up to one month, with a sensitivity of S = 5.75 kPa-1, r2 = 0.978 in the detection range 0-20 kPa, with robust operation under high humidity and extreme temperatures (−20 to 45 °C).
3 It accurately detects English alphabets, achieving 98% recognition accuracy using deep learning models.

Keywords

Wearable Organogel Deep learning Pressure sensor Bio-mechanical motion
Sharma, Kusum, Kousik Bhunia, Subhajit Chatterjee, Muthukumar Perumalsamy, Anandhan Ayyappan Saj, Theophilus Bhatti, Yung‑Cheol Byun, and Sang‑Jae Kim. 2025. “Deep Learning-Assisted Organogel Pressure Sensor for Alphabet Recognition and Bio-Mechanical Motion Monitoring”. Nano-Micro Letters 18 (September):63. https://doi.org/10.1007/s40820-025-01912-z.
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References
  1. Y. Sun, W. He, C. Jiang, J. Li, J. Liu et al., Wearable biodevices based on two-dimensional materials: from flexible sensors to smart integrated systems. Nano-Micro Lett. 17(1), 109 (2025). https://doi.org/10.1007/s40820-024-01597-w
  2. S. Ding, T. Saha, L. Yin, R. Liu, M.I. Khan et al., A fingertip-wearable microgrid system for autonomous energy management and metabolic monitoring. Nat. Electron. 7(9), 788–799 (2024). https://doi.org/10.1038/s41928-024-01236-7
  3. Y. Guo, K. Li, W. Yue, N.-Y. Kim, Y. Li et al., A rapid adaptation approach for dynamic air-writing recognition using wearable wristbands with self-supervised contrastive learning. Nano-Micro Lett 17(1), 41 (2024). https://doi.org/10.1007/s40820-024-01545-8
  4. K. Sharma, N.R. Alluri, A.P.S. Prasanna, M. Perumalsamy, A.A. Saj et al., Tunable phase-engineered polyhydroxybutyrate fibrous mat: an energy autonomous, temperature-responsive platform for wearable application. Adv. Fiber Mater. (2025). https://doi.org/10.1007/s42765-025-00555-4
  5. B. Ying, X. Liu, Skin-like hydrogel devices for wearable sensing, soft robotics and beyond. iScience 24(11), 103174 (2021). https://doi.org/10.1016/j.isci.2021.103174
  6. G. Chen, J. Huang, J. Gu, S. Peng, X. Xiang et al., Highly tough supramolecular double network hydrogel electrolytes for an artificial flexible and low-temperature tolerant sensor. J. Mater. Chem. A 8(14), 6776–6784 (2020). https://doi.org/10.1039/D0TA00002G
  7. D. Zhan, C. Fu, Z. Yu, G. Tian, Y. He et al., In-situ loaded PPy hydrogel for efficient atmospheric water harvesting without any energy consumption. Mater. Today Phys. 51, 101658 (2025). https://doi.org/10.1016/j.mtphys.2025.101658
  8. Y. Jiang, Y. Chen, W. Feng, S. Zhang, X. Zhong et al., Highly oxidation-resistant and rapid-gelation conductive hydrogels based on Fe3O4-assisted dopamine acrylamide@MXene for wearable sensors. Chem. Eng. J. 503, 158362 (2025). https://doi.org/10.1016/j.cej.2024.158362
  9. Q. Ding, Z. Wu, K. Tao, Y. Wei, W. Wang et al., Environment tolerant, adaptable and stretchable organohydrogels: preparation, optimization, and applications. Mater. Horiz. 9(5), 1356–1386 (2022). https://doi.org/10.1039/D1MH01871J
  10. Y. Chen, H. Ren, D. Rong, Y. Huang, S. He et al., Stretchable all-in-one supercapacitor enabled by poly(ethylene glycol)-based hydrogel electrolyte with low-temperature tolerance. Polymer 270, 125796 (2023). https://doi.org/10.1016/j.polymer.2023.125796
  11. J. Tang, Y. He, D. Xu, W. Zhang, Y. Hu et al., Tough, rapid self-recovery and responsive organogel-based ionotronic for intelligent continuous passive motion system. NPJ Flex. Electron. 7, 28 (2023). https://doi.org/10.1038/s41528-023-00259-y
  12. G. Su, Y. Zhang, X. Zhang, J. Feng, J. Cao et al., Soft yet tough: a mechanically and functionally tissue-like organohydrogel for sensitive soft electronics. Chem. Mater. 34(3), 1392–1402 (2022). https://doi.org/10.1021/acs.chemmater.1c04211
  13. F. He, S. Chen, R. Zhou, H. Diao, Y. Han et al., Bioinspired passive tactile sensors enabled by reversible polarization of conjugated polymers. Nano-Micro Lett. 17(1), 16 (2024). https://doi.org/10.1007/s40820-024-01532-z
  14. L. Zhao, X. Wang, X. Feng, W. Yang, Z. Wang et al., Environmentally stable and multi-functional conductive gelatin/PVA/black wattle bark tannin based organogel as strain, temperature and bioelectric sensor for multi-mode sensing. J. Colloid Interface Sci. 680, 795–808 (2025). https://doi.org/10.1016/j.jcis.2024.11.045
  15. M. Guo, Y. Xia, J. Liu, Y. Zhang, M. Li et al., Wearable pressure sensor based on triboelectric nanogenerator for information encoding, gesture recognition, and wireless real-time robot control. Adv. Funct. Mater. 35(22), 2419209 (2025). https://doi.org/10.1002/adfm.202419209
  16. Y. Zhang, X. Zhou, N. Zhang, J. Zhu, N. Bai et al., Ultrafast piezocapacitive soft pressure sensors with over 10 kHz bandwidth via bonded microstructured interfaces. Nat. Commun. 15(1), 3048 (2024). https://doi.org/10.1038/s41467-024-47408-z
  17. T.-W. Sun, M. Venkatesan, Y.-C. Hsu, J. Chandrasekar, W.-C. Chen et al., MXene-reinforced water insensitive self-healing piezoelectric nanogenerator for ambient and aquatic mechano-pressure sensing. Nano Energy 133, 110416 (2025). https://doi.org/10.1016/j.nanoen.2024.110416
  18. T. Wei, Z. Zhu, C. Hu, J. Zheng, B. Liu, Porous PVDF-based piezoelectric films applied in human motion detection exhibit excellent piezoelectric properties. J. Electron. Mater. 54(5), 3736–3746 (2025). https://doi.org/10.1007/s11664-025-11784-z
  19. D. Yao, W. Wang, H. Wang, Y. Luo, H. Ding et al., Ultrasensitive and breathable hydrogel fiber-based strain sensors enabled by customized crack design for wireless sign language recognition. Adv. Funct. Mater. 35(10), 2416482 (2025). https://doi.org/10.1002/adfm.202416482
  20. Y. Luo, H. Wang, Y. Liang, R. Xie, Z. Wu et al., Motion-interference free and self-compensated multi-receptor skin with all gel for sensory enhancement. Adv. Funct. Mater. (2025). https://doi.org/10.1002/adfm.202502196
  21. W. Wang, D. Yao, H. Wang, Q. Ding, Y. Luo et al., A breathable, stretchable, and self-calibrated multimodal electronic skin based on hydrogel microstructures for wireless wearables. Adv. Funct. Mater. 34(32), 2316339 (2024). https://doi.org/10.1002/adfm.202316339
  22. Z. Shi, L. Meng, X. Shi, H. Li, J. Zhang et al., Morphological engineering of sensing materials for flexible pressure sensors and artificial intelligence applications. Nano-Micro Lett. 14(1), 141 (2022). https://doi.org/10.1007/s40820-022-00874-w
  23. Z. Zhang, J. Li, H. Chen, H. Wang, Y. Luo et al., Scalable fabrication of uniform fast-response humidity field sensing array for respiration recognition and contactless human-machine interaction. Adv. Funct. Mater. (2025). https://doi.org/10.1002/adfm.202502583
  24. H. Wang, Q. Ding, Y. Luo, Z. Wu, J. Yu et al., High-performance hydrogel sensors enabled multimodal and accurate human–machine interaction system for active rehabilitation. Adv. Mater. 36(11), 2309868 (2024). https://doi.org/10.1002/adma.202309868
  25. J. Li, H. Wang, Y. Luo, Z. Zhou, H. Zhang et al., Design of AI-enhanced and hardware-supported multimodal E-skin for environmental object recognition and wireless toxic gas alarm. Nano-Micro Lett. 16(1), 256 (2024). https://doi.org/10.1007/s40820-024-01466-6
  26. L. Luo, Z. Wu, Q. Ding, H. Wang, Y. Luo et al., In situ structural densification of hydrogel network and its interface with electrodes for high-performance multimodal artificial skin. ACS Nano 18(24), 15754–15768 (2024). https://doi.org/10.1021/acsnano.4c02359
  27. X. Lin, F. Li, Y. Bing, T. Fei, S. Liu et al., Biocompatible multifunctional E-skins with excellent self-healing ability enabled by clean and scalable fabrication. Nano-Micro Lett. 13(1), 200 (2021). https://doi.org/10.1007/s40820-021-00701-8
  28. Y. Liang, Z. Wu, Y. Wei, Q. Ding, M. Zilberman et al., Self-healing, self-adhesive and stable organohydrogel-based stretchable oxygen sensor with high performance at room temperature. Nano-Micro Lett. 14(1), 52 (2022). https://doi.org/10.1007/s40820-021-00787-0
  29. K. Bhunia, E. Vijayakumar, N.P. Maria Joseph Raj, K. Serbara Bejigo, D. Kesavan et al., Cobalt nanop-integrated nitrogen-doped carbon nanotube as an efficient bifunctional electrocatalyst for direct methanol fuel cells. Chem. Eng. J. 473, 145028 (2023). https://doi.org/10.1016/j.cej.2023.145028
  30. R. Damayanti, Z. Alfian, M. Zulfajri, Biosynthesis of silver nanops loaded PVA/gelatin nanocomposite films and their antimicrobial activities. Inorg. Chem. Commun. 144, 109948 (2022). https://doi.org/10.1016/j.inoche.2022.109948
  31. J. Gamboa, S. Paulo-Mirasol, A. Espona-Noguera, H. Enshaei, S. Ortiz et al., Biodegradable conducting PVA-hydrogel based on carbon quantum dots: study of the synergistic effect of additives. J. Polym. Environ. 32(8), 3609–3626 (2024). https://doi.org/10.1007/s10924-023-03179-0
  32. A. Lobo-Guerrero, X-ray analysis and rietveld refinement of polyvinyl alcohol. Mater. Lett. 265, 127434 (2020). https://doi.org/10.1016/j.matlet.2020.127434
  33. R. Mao, D. Zhang, Z. Wang, H. Zhang, D. Wang et al., Deep-learning-assisted low-cost flexible cotton yarn-based triboelectric nanogenerator for ultra-sensitive human-computer merging interfaces. Nano Energy 111, 108418 (2023). https://doi.org/10.1016/j.nanoen.2023.108418
  34. Y. Qiao, J. Luo, T. Cui, H. Liu, H. Tang et al., Soft electronics for health monitoring assisted by machine learning. Nano-Micro Lett. 15(1), 66 (2023). https://doi.org/10.1007/s40820-023-01029-1
  35. M. Perumalsamy, A. Sathyaseelan, S. Kamalakannan, V. Elumalai, H.C. Ham et al., Tailoring the high-density active sites via metal-coordinated ionic liquid encapsulated trimetallic core-shell MOF-derived catalysts for superior ORR in flexible Al-air batteries. Energy Storage Mater. 70, 103447 (2024). https://doi.org/10.1016/j.ensm.2024.103447
  36. J. Chen, F. Liu, T. Abdiryim, X. Liu, An overview of conductive composite hydrogels for flexible electronic devices. Adv. Compos. Hybrid Mater. 7(2), 35 (2024). https://doi.org/10.1007/s42114-024-00841-6
  37. Q. Rong, W. Lei, L. Chen, Y. Yin, J. Zhou et al., Anti-freezing, conductive self-healing organohydrogels with stable strain-sensitivity at subzero temperatures. Angew. Chem. Int. Ed. 56(45), 14159–14163 (2017). https://doi.org/10.1002/anie.201708614
  38. S. Zhang, Z. Zhou, J. Zhong, Z. Shi, Y. Mao et al., Body-integrated, enzyme-triggered degradable, silk-based mechanical sensors for customized health/fitness monitoring and in situ treatment. Adv. Sci. 7(13), 1903802 (2020). https://doi.org/10.1002/advs.201903802
  39. Y. Zhao, H. Feng, Q. Shang, L. Jiao, Multifunctional robust dual network hydrogels constructed via dynamic physical bonds and carbon nanotubes for use as strain and pressure sensors. J. Sol-Gel Sci. Technol. 111(3), 834–849 (2024). https://doi.org/10.1007/s10971-024-06475-w
  40. Y. Tai, M. Mulle, I. Aguilar Ventura, G. Lubineau, A highly sensitive, low-cost, wearable pressure sensor based on conductive hydrogel spheres. Nanoscale 7(35), 14766–14773 (2015). https://doi.org/10.1039/C5NR03155A
  41. K. Zheng, C. Zheng, L. Zhu, B. Yang, X. Jin et al., Machine learning enabled reusable adhesion, entangled network-based hydrogel for long-term, high-fidelity EEG recording and attention assessment. Nano-Micro Lett. 17, 281 (2025). https://doi.org/10.1007/s40820-025-01780-7
  42. L. Huang, H. Guo, C. Long, J. Fu, W. Zeng et al., Regenerated silk fibroin-modified soft graphene aerogels for supercapacitive stress sensors. J. Electrochem. Soc. 168(11), 117511 (2021). https://doi.org/10.1149/1945-7111/ac34cb
  43. G. Ge, Y. Zhang, J. Shao, W. Wang, W. Si et al., Stretchable, transparent, and self-patterned hydrogel-based pressure sensor for human motions detection. Adv. Funct. Mater. 28(32), 1802576 (2018). https://doi.org/10.1002/adfm.201802576
  44. S. Xiang, X. He, F. Zheng, Q. Lu, Multifunctional flexible sensors based on ionogel composed entirely of ionic liquid with long alkyl chains for enhancing mechanical properties. Chem. Eng. J. 439, 135644 (2022). https://doi.org/10.1016/j.cej.2022.135644
  45. Z. Wang, Q. Cai, L. Lu, P.A. Levkin, High-performance pressure sensors based on shaped gel droplet arrays. Small 20(5), e2305214 (2024). https://doi.org/10.1002/smll.202305214
  46. S. Wang, Z. Chen, H. Zhou, X. Fu, B. Chen et al., Microporous MXene/polyurethane gels derived from iron foam templates for ultra-high stable pressure sensors and triboelectric nanogenerators. ACS Appl. Electron. Mater. 6(5), 3491–3500 (2024). https://doi.org/10.1021/acsaelm.4c00288
  47. Y. Xiao, H. Li, T. Gu, X. Jia, S. Sun et al., Ti3C2Tx composite aerogels enable pressure sensors for dialect speech recognition assisted by deep learning. Nano-Micro Lett. 17(1), 101 (2024). https://doi.org/10.1007/s40820-024-01605-z
  48. Y. Huang, B. Liu, W. Zhang, G. Qu, S. Jin et al., Highly sensitive active-powering pressure sensor enabled by integration of double-rough surface hydrogel and flexible batteries. NPJ Flex. Electron. 6, 92 (2022). https://doi.org/10.1038/s41528-022-00226-z
  49. Q. Liang, M. He, B. Zhan, H. Guo, X. Qi et al., Yolk-shell CoNi@N-doped carbon-CoNi@CNTs for enhanced microwave absorption, photothermal, anti-corrosion, and antimicrobial properties. Nano-Micro Lett. 17(1), 167 (2025). https://doi.org/10.1007/s40820-024-01626-8
  50. T. Hou, T. Wang, W. Mu, R. Yang, S. Liang et al., Nanop-loaded polarized-macrophages for enhanced tumor targeting and cell-chemotherapy. Nano-Micro Lett. 13(1), 6 (2020). https://doi.org/10.1007/s40820-020-00531-0
  51. Y. Xiao, Z. Tao, Y. Ju, X. Huang, X. Zhang et al., Diamond-like carbon depositing on the surface of polylactide membrane for prevention of adhesion formation during tendon repair. Nano-Micro Lett. 16(1), 186 (2024). https://doi.org/10.1007/s40820-024-01392-7
  52. J. Cao, C. Lu, J. Zhuang, M. Liu, X. Zhang et al., Multiple hydrogen bonding enables the self-healing of sensors for human–machine interactions. Angew. Chem. Int. Ed. 56(30), 8795–8800 (2017). https://doi.org/10.1002/anie.201704217
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