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Stretchable and suturable fibre sensors for wireless monitoring of connective tissue strain

Nature Electronics volume 4, pages 291–301 (2021)Cite this article

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Abstract

Implantable sensors can be used to monitor biomechanical strain continuously. However, three key challenges need to be addressed before they can be of use in clinical practice: the structural mismatch between the sensors and tissue or organs should be eliminated; a practical suturing attachment process should be developed; and the sensors should be equipped with wireless readout. Here, we report a wireless and suturable fibre strain-sensing system created by combining a capacitive fibre strain sensor with an inductive coil for wireless readout. The sensor is composed of two stretchable conductive fibres organized in a double helical structure with an empty core, and has a sensitivity of around 12. Mathematical analysis and simulation of the sensor can effectively predict its capacitive response and can be used to modulate performance according to the intended application. To illustrate the capabilities of the system, we use it to perform strain measurements on the Achilles tendon and knee ligament in an ex vivo and in vivo porcine leg.

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Fig. 1: Design for a wireless fibre strain-sensing system.
Fig. 2: Working mechanism of the fibre strain sensor.
Fig. 3: Performance of fibre strain sensor.
Fig. 4: Characterization and ex vivo demonstration of a wireless fibre strain-sensing system.
Fig. 5: Biocompatibility and in vivo demonstration of a wireless fibre strain-sensing system.

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Data availability

The raw data generated in this study are freely available from the corresponding authors on reasonable request.

Code availability

The custom code developed for recording data from the network analyser is available on Github at https://github.com/jaelee2020/suturable_fibre_strain_sensors.git.

References

  1. Rogers, J., Malliaras, G. & Someya, T. Biomedical devices go wild. Sci. Adv. 4, eaav1889 (2018).

    Article  Google Scholar 

  2. Yang, G., Rothrauff, B. B. & Tuan, R. S. Tendon and ligament regeneration and repair: clinical relevance and developmental paradigm. Birth Defects Res. C 99, 203–222 (2013).

    Article  Google Scholar 

  3. Boutry, C. M. et al. A stretchable and biodegradable strain and pressure sensor for orthopaedic application. Nat. Electron. 1, 314–321 (2018).

    Article  Google Scholar 

  4. Kubo, K., Kanehisa, H., Kawakami, Y. & Fukunaga, T. Influence of static stretching on viscoelastic properties of human tendon structures in vivo. J. Appl. Physiol. 90, 520–527 (2001).

    Article  Google Scholar 

  5. Bogaerts, S., Desmet, H., Slagmolen, P. & Peers, K. Strain mapping in the Achilles tendon—a systematic review. J. Biomech. 49, 1411–1419 (2016).

    Article  Google Scholar 

  6. Waugh, C. M., Blazevich, A. J., Fath, F. & Korff, T. Age-related changes in mechanical properties of the Achilles tendon. J. Anat. 220, 144–155 (2012).

    Article  Google Scholar 

  7. Cone, S. G. et al. Orientation changes in the cruciate ligaments of the knee during skeletal growth: a porcine model. J. Orthop. Res. 35, 2725–2732 (2017).

    Article  Google Scholar 

  8. McGilvray, K. C. et al. Implantable microelectromechanical sensors for diagnostic monitoring and post-surgical prediction of bone fracture healing. J. Orthop. Res. 33, 1439–1446 (2015).

    Article  Google Scholar 

  9. Roriz, P., Carvalho, L., Frazão, O., Santos, J. L. & Simões, J. A. From conventional sensors to fibre optic sensors for strain and force measurements in biomechanics applications: a review. J. Biomech. 47, 1251–1261 (2014).

    Article  Google Scholar 

  10. Hein, C., Wilton, P. & Wongworawat, M. D. Review of flexor tendon rehabilitation protocols following zone II repair. Crit. Rev. Phys. Rehabil. Med. 27, 11–18 (2015).

    Article  Google Scholar 

  11. Saini, N., Kundnani, V., Patni, P. & Gupta, S. Outcome of early active mobilization after flexor tendons repair in zones II-V in hand. Indian J. Orthop. 44, 314–321 (2010).

    Article  Google Scholar 

  12. Abdul Razak, A. H. et al. Foot plantar pressure measurement system: a review. Sensors 12, 9884–9912 (2012).

    Article  Google Scholar 

  13. Yeadon, M. R. & Challis, J. H. The future of performance‐related sports biomechanics research. J. Sports Sci. 12, 3–32 (1994).

    Article  Google Scholar 

  14. Tybrandt, K. et al. High-density stretchable electrode grids for chronic neural recording. Adv. Mater. 1706520, 1706520 (2018).

    Article  Google Scholar 

  15. Park, J. et al. Electromechanical cardioplasty using a wrapped elasto-conductive epicardial mesh. Sci. Transl. Med. 8, 344ra86 (2016).

    Article  Google Scholar 

  16. Kang, S.-K. et al. Bioresorbable silicon electronic sensors for the brain. Nature 530, 71–76 (2016).

    Article  Google Scholar 

  17. Khodagholy, D. et al. Organic electronics for high-resolution electrocorticography of the human brain. Sci. Adv. 2, e1601027 (2016).

    Article  Google Scholar 

  18. Rivas, L. et al. Micro-needle implantable electrochemical oxygen sensor: ex-vivo and in-vivo studies. Biosens. Bioelectron. 153, 112028 (2020).

    Article  Google Scholar 

  19. Dautta, M., Alshetaiwi, M., Escobar, J. & Tseng, P. Passive and wireless, implantable glucose sensing with phenylboronic acid hydrogel-interlayer RF resonators. Biosens. Bioelectron. 151, 112004 (2020).

    Article  Google Scholar 

  20. Zhou, J. et al. Top-down strategy of implantable biosensor using adaptable, porous hollow fibrous membrane. ACS Sens. 4, 931–937 (2019).

    Article  Google Scholar 

  21. Bai, W. et al. Bioresorbable photonic devices for the spectroscopic characterization of physiological status and neural activity. Nat. Biomed. Eng. 3, 644–654 (2019).

    Article  Google Scholar 

  22. Stauffer, F. et al. Soft electronic strain sensor with chipless wireless readout: toward real-time monitoring of bladder volume. Adv. Mater. Technol. 3, 1800031 (2018).

    Article  Google Scholar 

  23. Boutry, C. M. et al. Biodegradable and flexible arterial-pulse sensor for the wireless monitoring of blood flow. Nat. Biomed. Eng. 3, 47–57 (2019).

    Article  Google Scholar 

  24. Ma, Y. et al. Relation between blood pressure and pulse wave velocity for human arteries. Proc. Natl Acad. Sci. USA 115, 11144–11149 (2018).

    Article  Google Scholar 

  25. Kim, Y. J. et al. Protective effects of APOE e2 against disease progression in subcortical vascular mild cognitive impairment patients: a three-year longitudinal study. Sci. Rep. 7, 1910 (2017).

  26. Park, J. et al. Printing of wirelessly rechargeable solid-state supercapacitors for soft, smart contact lenses with continuous operations. Sci. Adv. 5, eaay0764 (2019).

    Article  Google Scholar 

  27. Lee, J. et al. Flexible, sticky, and biodegradable wireless device for drug delivery to brain tumors. Nat. Commun. 10, 5205 (2019).

    Article  Google Scholar 

  28. Lee, B. et al. Soft, skin-interfaced microfluidic systems with wireless, battery-free electronics for digital, real-time tracking of sweat loss and electrolyte composition. Small 14, 1802876 (2018).

    Article  Google Scholar 

  29. Colville, M. R., Marder, R. A., Boyle, J. J. & Zarins, B. Strain measurement in lateral ankle ligaments. Am. J. Sports Med. 18, 196–200 (1990).

    Article  Google Scholar 

  30. Race, A. & Amis, A. A. The mechanical properties of the two bundles of the human posterior cruciate ligament. J. Biomech. 27, 13–24 (1994).

    Article  Google Scholar 

  31. Frutiger, A. et al. Capacitive soft strain sensors via multicore-shell fiber printing. Adv. Mater. 27, 2440–2446 (2015).

    Article  Google Scholar 

  32. Cooper, C. B. et al. Stretchable capacitive sensors of torsion, strain, and touch using double helix liquid metal fibers. Adv. Funct. Mater. 27, 1605630 (2017).

    Article  Google Scholar 

  33. Yu, L. et al. Dual-core capacitive microfiber sensor for smart textile applications. ACS Appl. Mater. Interfaces 11, 33347–33355 (2019).

    Article  Google Scholar 

  34. Li, J. et al. Highly conductive PVA/Ag coating by aqueous in situ reduction and its stretchable structure for strain sensor. ACS Appl. Mater. Interfaces 12, 1427–1435 (2020).

    Article  Google Scholar 

  35. Pan, Z. et al. All-in-one stretchable coaxial-fiber strain sensor integrated with high-performing supercapacitor. Energy Storage Mater. 25, 124–130 (2020).

    Article  Google Scholar 

  36. Qu, Y. et al. Superelastic multimaterial electronic and photonic fibers and devices via thermal drawing. Adv. Mater. 30, 1707251 (2018).

    Article  Google Scholar 

  37. Xi, W., Yeo, J. C., Yu, L., Zhang, S. & Lim, C. T. Ultrathin and wearable microtubular epidermal sensor for real-time physiological pulse monitoring. Adv. Mater. Technol. 2, 1700016 (2017).

    Article  Google Scholar 

  38. Xi, W. et al. Soft tubular microfluidics for 2D and 3D applications. Proc. Natl Acad. Sci. USA 114, 10590–10595 (2017).

    Article  Google Scholar 

  39. Yu, L. et al. Highly stretchable, weavable, and washable piezoresistive microfiber sensors. ACS Appl. Mater. Interfaces 10, 12773–12780 (2018).

    Article  Google Scholar 

  40. Lee, J. et al. Highly sensitive multifilament fiber strain sensors with ultrabroad sensing range for textile electronics. ACS Nano 12, 4259–4268 (2018).

    Article  Google Scholar 

  41. Lion, A. A constitutive model for carbon black filled rubber: experimental investigations and mathematical representation. Contin. Mech. Thermodyn. 8, 153–169 (1996).

    Article  Google Scholar 

  42. Bergström, J. S. & Boyce, M. C. Constitutive modeling of the large strain time-dependent behavior of elastomers. J. Mech. Phys. Solids 46, 931–954 (1998).

    Article  MATH  Google Scholar 

  43. Jin, L. et al. Microstructural origin of resistance-strain hysteresis in carbon nanotube thin film conductors. Proc. Natl Acad. Sci. USA 115, 1986–1991 (2018).

    Article  Google Scholar 

  44. Sim, K. et al. Fully rubbery integrated electronics from high effective mobility intrinsically stretchable semiconductors. Sci. Adv. 5, eaav5749 (2019).

    Article  Google Scholar 

  45. Farris, D. J., Trewartha, G. & Polly McGuigan, M. Could intra-tendinous hyperthermia during running explain chronic injury of the human Achilles tendon? J. Biomech. 44, 822–826 (2011).

    Article  Google Scholar 

  46. Lai, A., Schache, A. G., Lin, Y. C. & Pandy, M. G. Tendon elastic strain energy in the human ankle plantar-flexors and its role with increased running speed. J. Exp. Biol. 217, 3159–3168 (2014).

    Google Scholar 

  47. Vörös, J. et al. Implantable analogue device and system comprising such device. European patent EP16172056.0 (2017).

  48. Lee, S. et al. Ag nanowire reinforced highly stretchable conductive fibers for wearable electronics. Adv. Funct. Mater. 25, 3114–3121 (2015).

    Article  Google Scholar 

  49. Lee, J. et al. Conductive fiber-based ultrasensitive textile pressure sensor for wearable electronics. Adv. Mater. 27, 2433–2439 (2015).

    Article  Google Scholar 

Download references

Acknowledgements

We thank T. Schlotter for his support with the numerical simulations. In addition, we thank T. Lee and K. Yoon of Yonsei University in South Korea for their help with the conductive fibres. This work was supported by the ETH Zurich Postdoctoral Fellowship Program, co-founded by the Marie Curie Actions for People COFUND Program, by ETH Zurich and SENESCYT and by the KRIBB (Korea Research Institute of Bioscience and Biotechnology) Research Initiative Program (KGM4252021), Korea. The work was also financed by the DGIST Start-up Fund Program of the Ministry of Science and ICT (2021010030), and the Korea Medical Device Development Fund grant, funded by the Korea government (the Ministry of Science and ICT) (project number 2020M3E5D8107020).

Author information

Authors and Affiliations

  1. Department of Robotics Engineering, Daegu-Gyeongbuk Institute of Science & Technology (DGIST), Daegu, Republic of Korea

    Jaehong Lee, Hwajoong Kim, Junwoo Yea, Chaewon Jin, Hongsoo Choi & Kyung-In Jang

  2. Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zürich, Zurich, Switzerland

    Jaehong Lee, Stephan J. Ihle, Guglielmo Salvatore Pellegrino, Byron Llerena Zambrano, Aline F. Renz, Csaba Forró & Janos Vörös

  3. Futuristic Animal Resource and Research Center & National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Ochang, Republic of Korea

    Chang-Yeop Jeon & Hee-Chang Son

  4. Department of Urology, University Hospital of Zurich, University of Zurich, Zurich, Switzerland

    Daniel Eberli & Florian Schmid

  5. Institute of Signal Processing and Wireless Communications, Zurich University of Applied Sciences, Winterthur, Switzerland

    Roland Küng

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Contributions

J.L. designed the overall concept and experiments, and performed all the tasks including the fabrication, measurements, data analysis and mathematical analysis. S.J.I. contributed to building the Python code for wireless measurement in the ex vivo experiment. G.S.P. conducted the finite element method simulation on the working mechanism of the fibre sensor. H.K., J.Y., C.-Y.J., H.-C.S. and K.-I.J. contributed to the in vivo experiments. C.J. and H.C. conducted the cell viability tests for demonstrating the biocompatibility of the system. D.E. and F.S. provided the professional suturing technique for the ex vivo experiment. B.L.Z. and A.F.R. contributed to the measurement experiments and data analysis. C.F. contributed to the analytical model of the sensor. R.K. performed the wireless measurement of the sensing system. J.V. contributed to the development of the sensor concept, data interpretation, mathematical analysis and critical revisions of the article.

Corresponding authors

Correspondence to Jaehong Lee or Janos Vörös.

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The authors declare no competing interests.

Additional information

Peer review information Nature Electronics thanks Roozbeh Ghaffari, John Ho, Chwee Lim and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–28 and six notes.

Reporting Summary

Supplementary Video 1

Behaviour of a double helical fibre strain sensor under tensile strain.

Supplementary Video 2

Suturing a fibre strain-sensing system on the Achilles tendon of a porcine leg.

Supplementary Video 3

Ex vivo demonstration of a fibre strain-sensing system.

Supplementary Video 4

In vivo demonstration of a fibre strain-sensing system.

Supplementary Video 5

X-ray video of an implanted fibre strain-sensing system during movements.

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Lee, J., Ihle, S.J., Pellegrino, G.S. et al. Stretchable and suturable fibre sensors for wireless monitoring of connective tissue strain. Nat Electron 4, 291–301 (2021). https://doi.org/10.1038/s41928-021-00557-1

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