Biodegradable and flexible arterial-pulse sensor for the wireless monitoring of blood flow

Abstract

The ability to monitor blood flow is critical to patient recovery and patient outcomes after complex reconstructive surgeries. Clinically available wired implantable monitoring technology requires careful fixation for accurate detection and needs to be removed after use. Here, we report the design of a pressure sensor, made entirely of biodegradable materials and based on fringe-field capacitor technology, for measuring arterial blood flow in both contact and non-contact modes. The sensor is operated wirelessly through inductive coupling, has minimal hysteresis, fast response times, excellent cycling stability, is highly robust, allows for easy mounting and eliminates the need for removal, thus reducing the risk of vessel trauma. We demonstrate the operation of the sensor with a custom-made artificial artery model and in vivo in rats. This technology may be advantageous in real-time post-operative monitoring of blood flow after reconstructive surgery.

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Fig. 1: Biodegradable, flexible and passive arterial-pulse sensor design.
Fig. 2: Wireless link design, simulation and optimization.
Fig. 3: Fringe-field capacitive sensor design and optimization.
Fig. 4: In vitro sensor characterization using an artificial artery model.
Fig. 5: In vivo sensor characterization.

Data availability

The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Information. Raw data generated for this study are available from the corresponding author on reasonable request.

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Acknowledgements

C.M.B. acknowledges postdoctoral fellowship support from the Swiss National Science Foundation (postdoc mobility fellowship no. P2EZP2_152118) and the European Commission (Marie Curie international outgoing fellowship grant no. 622362). L.B. and Y.K. acknowledge the Stanford ChEM-H Postdocs at the Interface seed grant. Part of this work was performed at the Stanford Nano Shared Facilities. A.C.H. acknowledges support from the National Science Foundation Graduate Research Fellowship (grant no. DGE-1147474).

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Contributions

C.M.B. and L.B. were the main contributors to this work and were responsible for elaboration of the sensor concept, development of new fabrication processes, performing all experiments for investigations into the materials, characterization of devices, data collection for in vitro experiments, data analysis and interpretation, and drafting of the article. L.B. and Y.K. performed the in vivo experiments. Y.K. performed implantation surgeries related to the in vivo studies, which included the design of the in vivo studies, development of the protocols, sensor implantation, operation studies and material biocompatibility studies. Y.K. also worked on data analysis and interpretation. C.V. contributed with the design of the LCR wireless sensor and performed all of the Computer Simulation Technology simulations. H.T. synthesized the biodegradable materials. A.C.H. and R.P. developed a new fabrication set-up for the fabrication of the Mg interconnect and provided critical revisions of the article. S.N. provided the initial Comsol simulations. J.L. and J.Cl. participated in the elaboration of the sensor concept, development of new fabrication processes and fabrication of the sensor. Z.W., J.Ch. and P.M.F. contributed to the design of the in vivo studies, working on the protocols and data interpretation. Y.K., P.M.F. and C.V. also contributed to the drafting and critical revision of the article. Z.B. contributed to the development of the sensor concept, fabrication processes, investigations of the materials, characterization of the devices, data interpretation and critical revisions of the article.

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Correspondence to Paige M. Fox.

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Stanford University has filed a provisional patent application (62750518) related to this technology.

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Supplementary information

Supplementary Information

Supplementary figures, table and discussion

Reporting Summary

Supplementary Video 1

Heart-pulse-rate measurement via external Doppler ultrasound during in vivo characterization

Supplementary Video 2

After 12 weeks of sensor implantation, the rat was able to move without any apparent limb impairment

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Boutry, C.M., Beker, L., Kaizawa, Y. et al. Biodegradable and flexible arterial-pulse sensor for the wireless monitoring of blood flow. Nat Biomed Eng 3, 47–57 (2019). https://doi.org/10.1038/s41551-018-0336-5

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