Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Low-cost gastrointestinal manometry via silicone–liquid-metal pressure transducers resembling a quipu


The evaluation of the tone and contractile patterns of the gastrointestinal (GI) tract via manometry is essential for the diagnosis of GI motility disorders. However, manometry is expensive and relies on complex and bulky instrumentation. Here we report the development and performance of an inexpensive and easy-to-manufacture catheter-like device for capturing manometric data across the dynamic range observed in the human GI tract. The device, which we designed to resemble the quipu—knotted strings used by Andean civilizations for the capture and transmission of information—consists of knotted piezoresistive pressure sensors made by infusing a liquid metal (eutectic gallium-indium) through thin silicone tubing. By exploring a range of knotting configurations, we identified optimal design schemes that led to sensing performances comparable to those of commercial devices for GI manometry, as we show for the sensing of GI motility in multiple anatomic sites of the GI tract of anaesthetized pigs. Disposable and customizable piezoresistive catheters may broaden the use of GI manometry in low-resource settings.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: QUILT.
Fig. 2: Experimental and numerical approaches to enhance sensor performance.
Fig. 3: Strategies for multiplexed measurements.
Fig. 4: In vivo demonstration of QUILT for gastrointestinal manometry.
Fig. 5: Benchmarking QUILT against clinically available pressure sensors.

Data availability

The main data supporting the results in this study are available within the paper and its Supplementary Information. Source data for the figures are available from figshare with the identifiers (Fig. 4) and (Fig. 5).

Code availability

The code used to generate the plots in Figs. 4c,d and 5g,j is available from the corresponding author on reasonable request.


  1. Fox, M. R. et al. Clinical measurement of gastrointestinal motility and function: who, when and which test? Nat. Rev. Gastroenterol. Hepatol. 15, 568–579 (2018).

    Article  Google Scholar 

  2. Peery, A. F. et al. Burden and cost of gastrointestinal, liver, and pancreatic diseases in the United States: update 2018. Gastroenterology 156, 254–272 (2019).

    Article  Google Scholar 

  3. Anderson, P. et al. Survey of digestive health across Europe: final report. Part 2: the economic impact and burden of digestive disorders. United European Gastroenterol. J. 2, 544–546 (2014).

    CAS  Article  Google Scholar 

  4. Moosavi, S., Rezaie, A., Pimentel, M. & Pichetshote, N. Atlas of High-resolution Manometry, Impedance, and pH Monitoring (Springer, 2020).

  5. Saltman, R., Bankauskaite, V. & Vrangbaek, K. Decentralization in Health Care. Strategies and Outcomes (McGraw-Hill, 2007).

  6. Aas, I. M. Organizational decentralization in radiology. J. Telemed. Telecare 12, 1–3 (2006).

    Article  Google Scholar 

  7. Al-Alusi, M. A., Ding, E., McManus, D. D. & Lubitz, S. A. Wearing your heart on your sleeve: the future of cardiac rhythm monitoring. Curr. Cardiol. Rep. 21, 158 (2019).

    Article  Google Scholar 

  8. Isakadze, N. & Martin, S. S. How useful is the smartwatch ECG? Trends Cardiovasc. Med. 30, 442–448 (2020).

    Article  Google Scholar 

  9. Ascher, M. The logical-numerical system of Inca quipus. IEEE Ann. Hist. Comput. 5, 268–278 (1983).

    Article  Google Scholar 

  10. Ascher, M. & Ascher, R. Mathematics of the Incas: Code of the Quipu (Courier Corporation, 2013).

  11. Dickey, M. D. et al. Eutectic gallium‐indium (EGaIn): a liquid metal alloy for the formation of stable structures in microchannels at room temperature. Adv. Funct. Mater. 18, 1097–1104 (2008).

    CAS  Article  Google Scholar 

  12. 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 

  13. Yeo, J. C., Yu, J., Koh, Z. M., Wang, Z. & Lim, C. T. Wearable tactile sensor based on flexible microfluidics. Lab Chip 16, 3244–3250 (2016).

    CAS  Article  Google Scholar 

  14. Gao, Y. et al. Wearable microfluidic diaphragm pressure sensor for health and tactile touch monitoring. Adv. Mater. 29, 1701985 (2017).

    Article  Google Scholar 

  15. Ma, Z. et al. Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics. Nat. Mater. 20, 859–868 (2021).

    CAS  Article  Google Scholar 

  16. Holloway, R. H. Esophageal manometry. GI Motility online (2006).

  17. Liem, O. et al. Solid‐state vs water‐perfused catheters to measure colonic high‐amplitude propagating contractions. Neurogastroenterol. Motil. 24, 345-e167 (2012).

    CAS  Article  Google Scholar 

  18. Lu, Y. et al. Transformable liquid-metal nanomedicine. Nat. Commun. 6, 10066 (2015).

    CAS  Article  Google Scholar 

  19. Yi, L. & Liu, J. Liquid metal biomaterials: a newly emerging area to tackle modern biomedical challenges. Int. Mater. Rev. 62, 415–440 (2017).

    CAS  Article  Google Scholar 

  20. Kim, K. et al. Highly sensitive and wearable liquid metal-based pressure sensor for health monitoring applications: integration of a 3D‐printed microbump array with the microchannel. Adv. Healthc. Mater. 8, 1900978 (2019).

    CAS  Article  Google Scholar 

  21. Chen, L. et al. Icing performance of superhydrophobic silicone rubber surfaces by laser texturing. Mater. Res. Express 6, 1250e2 (2020).

    Article  Google Scholar 

  22. Araromi, O. A. et al. Ultra-sensitive and resilient compliant strain gauges for soft machines. Nature 587, 219–224 (2020).

    CAS  Article  Google Scholar 

  23. Han, M. et al. Catheter-integrated soft multilayer electronic arrays for multiplexed sensing and actuation during cardiac surgery. Nat. Biomed. Eng. 4, 997–1009 (2020).

    CAS  Article  Google Scholar 

  24. Bredenoord, A. J. et al. Chicago classification criteria of esophageal motility disorders defined in high resolution esophageal pressure topography. Neurogastroenterol. Motil. 24, 57–65 (2012).

    Article  Google Scholar 

  25. Hansen, M. B. Small intestinal manometry. Physiol. Res. 51, 541–556 (2002).

    CAS  PubMed  Google Scholar 

  26. Pfeifer, J. & Oliveira, L. in Constipation (eds Wexner, S. D. & Duthie, D. S.) 71–83 (Springer, 2006).

  27. Shaker, A. et al. Multiple rapid swallow responses during esophageal high-resolution manometry reflect esophageal body peristaltic reserve. Am. J. Gastroenterol. 108, 1706–1712 (2013).

    Article  Google Scholar 

  28. Leber, A. et al. Soft and stretchable liquid metal transmission lines as distributed probes of multimodal deformations. Nat. Electron. 3, 316–326 (2020).

    Article  Google Scholar 

  29. Yu, X. et al. Skin-integrated wireless haptic interfaces for virtual and augmented reality. Nature 575, 473–479 (2019).

    CAS  Article  Google Scholar 

  30. Bellinger, A. M. et al. Oral, ultra-long-lasting drug delivery: application toward malaria elimination goals. Sci. Transl. Med. 8, 365ra157 (2016).

    Article  Google Scholar 

  31. Hosotsubo, M., Magota, T., Egusa, M., Miyawaki, T. & Matsumoto, T. Fabrication of artificial food bolus for evaluation of swallowing. PLoS ONE 11, e0168378 (2016).

    Article  Google Scholar 

  32. Cheeney, G., Nguyen, M., Valestin, J. & Rao, S. S. C. Topographic and manometric characterization of the recto‐anal inhibitory reflex. Neurogastroenterol. Motil. 24, e147–e154 (2012).

    CAS  Article  Google Scholar 

  33. Lee, T. H. & Bharucha, A. E. How to perform and interpret a high-resolution anorectal manometry test. J. Neurogastroenterol. Motil. 22, 46–59 (2016).

    Article  Google Scholar 

  34. Gourcerol, G. et al. Do endoflip assessments of anal sphincter distensibility provide more information on patients with fecal incontinence than high‐resolution anal manometry? Neurogastroenterol. Motil. 28, 399–409 (2016).

    CAS  Article  Google Scholar 

  35. Zifan, A., Sun, C., Gourcerol, G., Leroi, A. M. & Mittal, R. K. Endoflip vs high‐definition manometry in the assessment of fecal incontinence: a data‐driven unsupervised comparison. Neurogastroenterol. Motil. 30, e13462 (2018).

    Article  Google Scholar 

  36. De Schepper, H. U. et al. Impact of spatial resolution on results of esophageal high‐resolution manometry. Neurogastroenterol. Motil. 26, 922–928 (2014).

    Article  Google Scholar 

  37. Sundaram, S. et al. Learning the signatures of the human grasp using a scalable tactile glove. Nature 569, 698–702 (2019).

    CAS  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).

    CAS  Article  Google Scholar 

  39. Luo, Y. et al. Learning human–environment interactions using conformal tactile textiles. Nat. Electron. 4, 193–201 (2021).

    Article  Google Scholar 

Download references


We thank A. M. Hayward, K. Ishida and J. Jenkins for supervising and performing the in vivo experiments using Yorkshire swine models; M. Kolle for insightful discussions on knot mechanics; and H. Luan for helping with finite-element modelling. This work was supported in part by the Karl van Tassel (1925) Career Development Professorship and the Department of Mechanical Engineering, MIT.

Author information

Authors and Affiliations



K.N. and G.T. conceived and designed the study. K.N. fabricated and characterized the QUILT. S.B., C.M.P. and A.M.J. performed the mechanical analysis and the finite-element modelling. J.L.P.K., K.N., S.S.S. and V.R.F. performed the in vivo experiments on porcine models. V.R.F. synthesized and optimized the artificial food bolus. W.W.C. advised on the clinical aspects of this project and wrote a substantial portion of the manuscript. All authors discussed and interpreted the results, and participated in writing and editing the manuscript.

Corresponding author

Correspondence to Giovanni Traverso.

Ethics declarations

Competing interests

The authors report a patent application (U.S. Provisional Application No. 63/301,491) describing the system described for manometric evaluation. Complete details of all for-profit and not-for-profit relationships for G.T. are included in the Supplementary Information. The other authors declare no competing interests.

Peer review

Peer review information

Nature Biomedical Engineering thanks Michael Dickey, Pankaj Pasricha and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Table 1, Figs. 1–19, References, video captions and details of competing interests for G.T.

Reporting Summary

Peer Review File

Supplementary Video 1

Formation of an elastic overhand knot using finite-element simulations.

Supplementary Video 2

Finite-element simulations of knot compression.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Nan, K., Babaee, S., Chan, W.W. et al. Low-cost gastrointestinal manometry via silicone–liquid-metal pressure transducers resembling a quipu. Nat. Biomed. Eng (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing