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Biomedical devices

Robotic insulin delivery via smart ingestible capsules

10 Sep 2021
Implantable insulin delivery system
Insulin delivery system: The device (left) contains four actuators (1, docking; 2, needle ejection; 3, variable volume reservoir; 4, infusion pump) and several operating blocks. The complete prototype (right) includes the external charging coil, the pill and the 78 x 63 x 35 mm implantable device. (Courtesy: Sci. Robotics 10.1126/scirobotics.abh3328 (2021))

The year 2021 marks the 100th anniversary of the discovery of insulin. Since then, insulin has become the safest glucose-lowering therapy for diabetes, administered to patients using syringes, pens and pumps.

But among other barriers to achieving glycaemic control physiologically, some patients find it difficult to inject insulin multiple times per day.

Researchers at Scuola Superiore Sant’Anna and clinicians at the University of Pisa are part of a growing movement to develop closed-loop insulin delivery systems that are completely internal to the human body.

Swallowing your insulin

It all started at a summer school – the idea to use a pill-like capsule as a vehicle for insulin cargo, that is.

Doctoral students and their tutors were brainstorming non-invasive intraperitoneal approaches to restore blood glucose to normal levels in type 1 diabetes patients. They ultimately decided to access the body’s internal organs using smart, drug-loaded ingestible capsules that unload at a device anchored outside the peritoneum, the thin, transparent membrane that lines the walls of the abdominal cavity and encloses the abdominal organs.

Scuola Superiore Sant’Anna professor of bioengineering Arianna Menciassi and the students patented the ensuing robotic device and capsule-based refilling system.

Unlike devices used today, which need external pumps or reservoirs that can introduce complications such as catheter obstructions and pain, the researchers’ implantable robotic device and microinfusion system refills via ingestible magnetic capsules that carry insulin.

Once swallowed, an insulin-filled capsule is carried through the digestive tract by peristalsis until it docks at a pouch containing the device and another small magnet, where a retractable needle punctures the intestinal layer and the peritoneum before poking a hole in the capsule. Once this hole is created, the insulin inside is transferred to the implanted reservoir. The now-empty pill undocks, and the device releases the insulin.

In its current iteration, the implanted device is comparable in size with those available commercially. It’s around 165 g, about the weight of an apple, and is about 1.5 times the size of an Apple AirPods Pro charging case.

Advances in medical robotics

The researchers tested their robot and smart pills in human cadavers and live pigs, monitoring the docking process using fluoroscopy.

“This is the first animal study demonstrating that the intraperitoneal route for physiological hormone delivery is feasible, and that the implanted system for delivery can be refilled by swallowing a simple pill which acts as a refiller shuttle,” says Menciassi.

In theory, the robotic device could be used throughout a person’s life. It recharges wirelessly and is equipped with Bluetooth so that a patient can always remain in contact with the device.

Next on the researchers’ agenda is to optimize the design of the device and solve some engineering challenges, such as improving battery recharge, before conducting more animal trials and pilot tests.

The researchers anticipate it will take three to four years to complete human studies and certify the device before moving to commercialization.

Menciassi hopes this study will “increase the interest and the efforts for in vivo and implantable robotic devices.”

Learn more about the device in Science Robotics.

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