Decay, made visible: every streak a particle spending its half-life — the rain a patient collector could drink.
Michael F. Schoenitzer, CC BY-SA 4.0, via Wikimedia CommonsThe Nuclear Line: reviving the atomic heartbeat
US 10,096,393US 10,811,157US 11,881,325US 10,818,811US 11,189,390
The problem A chronic implant asks for microwatts, for decades, with no recharge and no second surgery. Chemistry counts its life in charge cycles; a radioisotope counts in half-lives.
A cross-section of the whole betavoltaic cell: a sponge-like tangle of interconnected 3D nanostructures, each lobe traced with thin coating layers, filling the gap between two flat electrode plates top and bottom.
United States Patent and Trademark Office · public domainThe historical arcT2 · external source
Medtronic has been here before. The first nuclear-powered pacemaker was implanted in 1970 (Doyle, "Rise and Fall of the Nuclear Pacemaker"), and in the early 1970s Medtronic teamed with the French company Alcatel on a plutonium-238-powered pacemaker whose decay heat drove a thermoelectric stack (Medical Design & Outsourcing). Hundreds were implanted (a Newark hospital alone tracked 155 units; one French series counted 325 patients — Doyle), and the longevity was astonishing: one 1973 recipient's device was still pacing 34 years later, where a chemical battery would have demanded repeated replacement surgeries (ORAU Museum of Radiation, accessed 2026-07-22; details re-attributed to their specific sources after adversarial QA). The approach faded — regulation, plutonium logistics, and the lithium-iodine battery won — but the dream (a power source that outlives the patient's need) never died.
The problemT1 · from the patentUS10096393B2
Modern betavoltaics skip the heat step: beta particles from a decaying isotope strike a semiconductor junction and generate electron-hole pairs directly, like a solar cell lit by radiation instead of sunlight. The catch — per the patent's description of what its 3D architecture improves (the background itself is a neutral recital of prior converters): flat junctions offer limited collection surface, and charge carriers can recombine before they're collected.
A flat collector catches only what falls upon it. A three-dimensional sponge stands inside the rain of beta particles and drinks from every direction at once — each absorbed glow a fraction of a microwatt, for decades.
An original instrument of the houseThe principleT1 · from the patentUS10096393B2
Make the collector three-dimensional. Claim 1 builds the converter around a 3D current collector — nanorods, nanotubes, metal foam — coated with a charge-carrier separator (quantum dots are among the named embodiments) and a hole-conductor layer, with the radiation source placed so particles strike the separator. The nanostructure can "maximize a surface area … for any given volume" (verbatim, ellipsis ours), so far more of each particle's energy finds a junction before recombining. Named fuel candidates run from tritium to Ni-63 to Sr-90. A sibling line (US10818811) takes a different path: isotope → phosphor light → photovoltaic — a glow-in-the-dark battery, hermetically sealed by the same packaging craft as everything else in the corpus.
Plain-English registerT3 · interpretationconfidence: high
A flat solar panel wastes a floodlight shining from every direction. Crumple the panel into a sponge and hang the light inside it, and almost every ray lands on a working surface. That's the 3D collector — a sponge for radiation.
Honest statusT3 · interpretationconfidence: medium
Five grants (2018–2024) and sustained follow-on filings show real Medtronic investment, but no public source indicates a shipped nuclear-powered Medtronic product today — we don't claim one. What the record supports: this is forward-looking R&D reconnecting the company to its own atomic history, aimed at the same prize the 1970 device chased — implants that never need a battery change.
Engineers bolting a radioisotope generator onto the Cassini spacecraft — decades of power without recharge, the same wager at planetary scale.
NASA, public domain, via Wikimedia CommonsSupporting Plates
A magnified slice through one coated wall of the sponge, with quantum dots drawn as dark circles in the layer stack and arrows tracing beta particles striking in and freed electric charges being pulled apart across the layers.
United States Patent and Trademark Office · public domain
A close-up cross-section of an alternate layer stack, again with quantum dots embedded in the coating and arrows showing radiation particles arriving and the resulting positive and negative charges separating toward opposite layers.
United States Patent and Trademark Office · public domainWhile startups made the 2024 microbattery news cycle, the three-dimensional collector had been claimed — across tritium, nickel-63, and other beta fuels — with priority back in 2014.