Novel Low-Cost and Disposable GI Manometry Devices to Broaden Use in Low-Resource Settings

Standard digital manometer for GI diagnosis.

Manometry is one of the most important tools in evaluating gastrointestinal (GI) dysmotility. It provides information usually unavailable from conventional imaging and endoscopy. GI manometers are catheter-like devices that contain a series of pressure transducers along their length to measure real-time pressure changes in the GI tract. These complex electronic devices are expensive and bulky and must be chemically disinfected—attributes that limit their use in low-income regions of the world and non-hospital settings.

Working with scientists at MIT, Brigham and Women’s Hospital researchers have developed much simpler alternatives called quipu-inspired, liquid metal–enabled pressure transducers (QUILT). Kewang Nan, PhD, a research scientist at MIT and collaborator at the Brigham, Sahab Babaee, PhD, a research scientist at MIT and collaborator at the Brigham in the Division of Gastroenterology, Hepatology and Endoscopy, Giovanni Traverso, MB, BChir, PhD, a gastroenterologist and biomedical engineer in that division, and colleagues describe the new devices in Nature Biomechanical Engineering.

Fabrication of QUILT

A quipu is an ensemble of knotted cords originated by Andean cultures to store and communicate information. The colors, spatial distributions, and configurations of the knots can convey dates, statistics, and abstract ideas.

The researchers filled a silicone catheter with gallium–indium eutectic (EGaIn), a liquid metal. Inspired by the quipu design, they knotted it at intervals in various configurations, elongating the cross-section of the catheter and making it easier to compress. The otherwise insensitive silicone/EGaIn composite became capable of detecting pressure changes across the range encountered in the human GI tract.

Optimization and Initial Testing of QUILT

Using basic bench tools, it was possible to manufacture a simple QUILT for less than 26 cents per centimeter. However, this created challenges such as high uncertainties in the sensitivity of certain knot types. The researchers developed a mechanical stretching system with an integrated force gauge to precisely control the knotting process.

They also introduced multiplexing by tying multiple knots onto a single conductor, minimizing the number of channels required without requiring expensive multiplexer circuits. Three modes of multiplexing were devised, each with a different number of channels and knot configurations to allow different types of measurements.

Through in vitro tests, the research team validated QUILT pressure sensing in a wide range of force scenarios. They also found the devices can undergo at least 10 cycles of sterilization in a standard autoclave without loss of sensitivity.

In Vivo Testing and Benchmarking

In pigs, the team validated the utility of QUILT for measuring esophageal pressure during the passage of an artificial food bolus and rectoanal pressure during the rectoanal inhibitory reflex (RAIR).

The researchers also used porcine models to benchmark QUILT against two commercially available pressure sensors: the MedTronic endoluminal functional luminal-imaging probe (Endoflip), and the MedTronic ManoScan 360 system for high-resolution manometry. Esophageal and RAIR measurements were comparable between QUILT and the established systems.

Continued Scrutiny Needed

Additional experiments, improvements, and human trials will be necessary before QUILT can be used clinically. However, these devices are expected to be inexpensive, portable, and perhaps disposable.

Those attributes would be beneficial even in resource-rich regions. GI manometers are complex and costly to disassemble and disinfect, which increases the risk of cross-contamination and reduces the number of procedures that can be scheduled per day.

QUILT might even prove to be suitable for household use, promoting the trend toward decentralization of GI-related health care.

Leave a Reply