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A compact, wireless system for continuous monitoring of breast milk expressed during breastfeeding

Nature Biomedical Engineering (2025)Cite this article

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Abstract

Human milk is the ideal source of nutrition for infants. Most health organizations recommend direct breastfeeding from the first hour of life, extending throughout the first and second year. However, uncertainties regarding the volumes of milk ingested by the infant contribute to suboptimal rates of breastfeeding. Here we introduce a compact and unobtrusive device that gently interfaces to the breast via four electrodes and accurately measures expressed milk volume during breastfeeding through changes in the alternating current impedance. The data pass wirelessly to a smartphone continuously throughout each breastfeeding session for real-time graphical display. Comprehensive experimental and computational results establish the operating principles and guide engineering choices for optimized performance. Evaluations with 12 breastfeeding mothers over periods of as long as 17 weeks in the neonatal intensive care unit and in home settings illustrate the practical utility of this technology in addressing a critically important unmet need in maternal and neonatal care.

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Fig. 1: Wearable wireless system and operating principles for continuous monitoring of breast milk released during nursing.
Fig. 2: Verification of phantom model.
Fig. 3: Human body simulation results for breast milk monitoring through measurements of bioimpedance.
Fig. 4: Continuous wireless monitoring of milk released from the breast of a new mother recorded in a NICU setting.
Fig. 5: Clinical studies from various participants with replicate measurements over periods of days, weeks and months.

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Data availability

The data supporting the results in this study are available within the paper and its Supplementary Information. The data used in the study are not publicly available because they contain information that could compromise research participant privacy. Anonymized data can be made available from the corresponding authors on request for academic purposes. Sample data are available on GitHub at https://github.com/JH127/Sample-data (ref. 35).

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Acknowledgements

This work was supported by the Querrey Simpson Institute for Bioelectronics at Northwestern University. S.O. acknowledges funding from a National Research Foundation of Korea (NRF) grant (2021R1C1C2010180) funded by the Korea government (MSIT), and the DHA SBIR Phase II award (W81XWH22C0106). R.A. acknowledges support from the ASME—Applied Mechanics Division Haythornthwaite Foundation Research Initiation Grant. J.-Y.Y. acknowledges funding from the Basic Research Laboratory (BRL) Project of National Research Foundation (RS-2024-00406674) funded by the Ministry of Science and ICT of Korea, as well as the Technology Innovation Program (RS-2024-00443121) funded by the Ministry of Trade Industry and Energy (MOTIE, Korea).

Author information

Author notes

  1. These authors contributed equally: Jihye Kim, Seyong Oh, Raudel Avila.

Authors and Affiliations

  1. Department of Molecular Science and Technology, Ajou University, Suwon, Republic of Korea

    Jihye Kim

  2. Advanced College of Bio-convergence Engineering, Ajou University, Suwon, Republic of Korea

    Jihye Kim

  3. Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL, USA

    Seyong Oh, Hee-Sup Shin, Anthony R. Banks, Yonggang Huang & John A. Rogers

  4. Division of Electrical Engineering, Hanyang University ERICA, Ansan, Republic of Korea

    Seyong Oh

  5. Department of Mechanical Engineering, William Marsh Rice University, Houston, TX, USA

    Raudel Avila

  6. School of Science and Engineering, University of Missouri, Kansas City, MO, USA

    Hee-Sup Shin

  7. Haku Technology, San Diego, CA, USA

    Matthew Banet

  8. Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA

    Jennifer Wicks, Daniel T. Robinson & Craig F. Garfield

  9. Ann and Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, USA

    Jennifer Wicks, Daniel T. Robinson & Craig F. Garfield

  10. Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA

    Yonggang Huang

  11. Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, USA

    Yonggang Huang

  12. Department of Material Science and Engineering, Northwestern University, Evanston, IL, USA

    Yonggang Huang & John A. Rogers

  13. Department of Semiconductor Convergence Engineering, Sungkyunkwan University, Suwon, Republic of Korea

    Jae-Young Yoo & John A. Rogers

  14. Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA

    John A. Rogers

  15. Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA

    John A. Rogers

Authors
  1. Jihye Kim
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Contributions

J.K., S.O., J.-Y.Y. and J.A.R. conceived of the idea and designed the research. J.K., S.O., H.-S.S., M.B., A.R.B., J.-Y.Y. and J.A.R. performed experiments and analysed data. R.A. and Y.H. performed electrical field modelling. J.K., J.W., D.T.R. and C.F.G. performed human clinical studies. J.K., S.O., R.A., J.W., J.-Y.Y., D.T.R., C.F.G. and J.A.R. wrote and edited the paper.

Corresponding authors

Correspondence to Jae-Young Yoo, Daniel T. Robinson, Craig F. Garfield or John A. Rogers.

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Nature Biomedical Engineering thanks Wei Gao, John Ho and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Kim, J., Oh, S., Avila, R. et al. A compact, wireless system for continuous monitoring of breast milk expressed during breastfeeding. Nat. Biomed. Eng (2025). https://doi.org/10.1038/s41551-025-01393-w

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