ETH Zurich implant clears glucose via electrocatalysis, no drugs

An implantable electronic device developed at ETH Zurich restored elevated blood glucose to the normal range in obese diabetic mice within one hour, using an electrically driven chemical reaction rather than any drug. The team, led by Martin Fussenegger, reports the ECHO device in Science.

The name stands for electrocatalytic closed-loop health optimization. Its working element is a catalyst made of gold nanoclusters dusted with platinum particles, embedded in a conductive porous graphite felt. Control electronics and a wireless power receiver sit alongside the catalyst inside a 3D-printed polyamide casing, and the whole assembly is encapsulated in a biocompatible cellulose-alginate-albumin coating.

The device is designed for implantation under the skin. When powered wirelessly, it oxidizes glucose into gluconate, which the kidneys then clear. The catalyst never touches circulating blood directly; it interacts with glucose in the interstitial fluid, the liquid between cells and capillaries that continuously exchanges glucose with the bloodstream.

"Most patients with type 2 diabetes are treated with glucose-lowering medications, including metformin, SGLT2 inhibitors or GLP-1 receptor agonists, while some also require insulin injections," Fussenegger explains. "Our approach explores a fundamentally different possibility: regulating blood glucose through an electronically controlled chemical reaction rather than administering a drug."

Type 2 diabetes and the obesity that often accompanies it affect more than 2.5 billion people worldwide. Existing drug regimens can be limited by side effects, low adherence or incomplete metabolic control.

What did the mouse studies measure?

The researchers implanted ECHO devices in obese type 2 diabetic mice and tested various voltages and currents. Low-power activation at 0.75 V and 10 mA brought elevated blood glucose back to the normal range within one hour. Daily 60-minute activation sessions maintained glucose control for at least six weeks, with no detectable hypoglycaemia (blood glucose below normal levels).

The metabolic consequences went beyond glucose. Because the body could not rely on circulating glucose, it shifted toward burning stored fat. Treated mice lost up to 10% of their body weight and showed lower circulating triglycerides (a type of fat found in the blood), with no change in food intake. The animals tolerated the implant well: no adverse physiological, inflammatory or behavioural effects, and no signs of electrical or thermal tissue damage. The device remained functional and reliable across the full six-week treatment.

Does it work as a closed-loop system?

ECHO can connect to wearables or smartphones for real-time monitoring. In a demonstrated set-up, a commercial continuous glucose monitor tracked glucose levels and sent the data to a smartphone, which switched the implant on when readings exceeded a threshold and off again once levels normalized.

The team tested threshold concentrations of 5 to 15 mM with activation cycles of 5 to 30 minutes. The device performed at every threshold. Five-minute cycles provided stable glucose control without hypoglycaemic episodes over the licensed 12-day lifespan of the glucose monitor.

"Conventional closed-loop insulin delivery systems still depend on a supply of insulin, whereas our system removes excess glucose directly through electrocatalysis, without requiring stored drugs, engineered cells or replenishable therapeutic reservoirs," says Fussenegger. "This could ultimately provide a more autonomous approach to glucose management."

What stands between ECHO and the clinic?

The central engineering problem is scale. Human glucose turnover is far greater than that of a mouse, so the electrocatalytic capacity must grow accordingly. "We have already conducted experiments using a 5 l fluid volume, corresponding approximately to the total blood volume of an adult human, providing encouraging evidence for the scalability of our approach," Fussenegger notes.

That benchtop volume test is a projection-supporting result, not a measured in vivo outcome; the in vivo data remain mouse-only. Next, the group plans to assess glucose regulation, long-term safety and device performance in larger animals whose physiology more closely resembles ours, while optimizing the catalyst's efficiency, durability and the implant's size.

Fussenegger frames the work as an early entry in what he calls electrocatalytic medicine, in which electronically controlled chemical reactions could complement or replace drugs for selected metabolic diseases.