The Sealed Machine · a reading in six movements

The body, kept in time.

In 1961 a pacemaker was a box you carried, with a dial you could turn. Sixty years later it is a grain of titanium that rides inside the heart itself. Between those two machines runs a quieter story — fifty-six United States patents by David A. Ruben of Medtronic, the engineering one layer down that decides whether any of it survives a decade sealed in a living body.

Black-and-white photograph of two hands adjusting the dials of a boxy 1961 Medtronic external pacemaker.
Era zero. Hands on a Medtronic external pacemaker, 1961 — the machine still outside the body, still adjusted by touch. Everything that follows is the long work of bringing it inside, and sealing the door. Hands holding a Medtronic external pacemaker, 1961 — Warren K. Leffler, U.S. News & World Report Magazine Photograph Collection, Library of Congress — public domain, via Wikimedia Commons.

One layer down

He never worked at the surface where devices win.

Ruben’s filings run from 1993 to 2025; his grants from 1996 to 2026 — a thirty-three-year line with no gap. Almost none of it is therapy. It is packaging: hermetic housings and feedthroughs, laser joints, pressure and motion sensors, radioisotope power — the promises a device must keep before it is allowed to keep a heart. Nothing leaks in. Nothing leaks out. For a decade or more, in warm salt water.

The record is legible in the way patents are: later inventors citing his work more than a thousand times, continuation families stretching across decades, and one 1997 accelerometer patent — a crystal beam with a stop to catch it — cited by 203 later inventions.

56US patents granted
33years of filings, unbroken
6engineering clusters
1,028forward citations

Six lives of the work

Each line of patents is a life: a problem met young and kept for decades.

A perspective assembly view with the lid half pulled away from the main shell, exposing the connector hardware between them — the connector block, setscrew, spring contact, feedthrough pin, and sealing plug all floating in their positions like a freeze-frame of the device being put together. 1993-1996 1993: The First Housing The 1993 origin: a pacemaker body whose parts seat themselves before one lid closes it forever. Read the movement → The central-rail-stop sensor in three views — assembled block, end-on cross-section, and full exploded stack — showing the piezoelectric beam suspended between a grooved cover and base whose center rails let it flex normally but catch its free end before a shock can snap it. 1997-2001 The Accelerometer Line: teaching the pacemaker to feel motion A crystal diving-board that feels a footstep — and the stop that kept it from snapping. Read the movement → A full cross-sectional schematic of the welding apparatus, tracing the laser beam from its source through a turning mirror and focusing lens down a conical housing and out through the bond head's aperture onto the ribbon-and-pad joint. 2000-2025 The Laser Craft: light as a precision tool Light as the joining tool: heat placed exactly at the seam, withdrawn before it can wander. Read the movement → The invention in action: a cross-section with laser-energy arrows firing up through the transparent substrate to weld contact to substrate, plus a plan view of the resulting concentric ring-shaped bond lines encircling the central via like a bullseye. 2014-2024 The Feedthrough Line: wiring through an unbroken wall Wiring through an unbroken wall — a ring of laser light where a furnace used to be. Read the movement → 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. 2015-2024 The Nuclear Line: reviving the atomic heartbeat The atomic heartbeat revived: decay itself as a battery measured in decades. Read the movement → An exploded perspective view of the valve assembly pulled apart into its stack: the inlet connector and domed housing with its ball-and-cone valve seat on top, the cross-hatched flexible membrane disc beneath it, the plate carrying the MEMS actuators and electronics below that, and the fluid reservoir base at the bottom. 2020-2024 The Valve: engineering mercy for hydrocephalus A MEMS valve metering fluid from a child’s brain — engineering as a form of mercy. Read the movement →

Where it was all going

The endpoint of the lineage is small enough to live inside the heart.

Chest X-ray: the ribcage and heart of an elderly patient, with a tiny Medtronic Micra leadless pacemaker capsule glowing bright inside the heart.
A chest radiograph of a 95-year-old patient. The bright capsule inside the heart is a Medtronic Micra — a complete leadless pacemaker, hermetically sealed, resting where the therapy is needed. Every discipline in this archive — the housing that assembles itself, the feedthrough that wires through an unbroken wall, the laser that seals without scorching, the sensor that feels a footstep — had to shrink and hold for this photograph to exist. Chest X-ray with a Medtronic Micra leadless pacemaker in the heart — Hellerhoff, CC BY-SA 4.0, via Wikimedia Commons.

The present tense

The promise, tested; the people it is for.

A gloved FDA engineer's hand holding a sealed titanium pacemaker with coiled leads above a laboratory test bath.
An FDA engineer holds a sealed pacemaker over a test bath. Hermeticity is not a mood; it is measured, in warm salt water, before any promise is made. FDA engineer holding an implantable pacemaker over a laboratory test bath — U.S. Food and Drug Administration — public domain, via Wikimedia Commons.
An adult with type 1 diabetes wearing an insulin pump clipped at the waist and a continuous glucose sensor on the skin.
The same engineering worn on a living body: an insulin pump and a glucose sensor, quietly keeping a different rhythm. The sensor patents in this corpus belong to this person’s ordinary day. Adult with type 1 diabetes wearing an insulin pump and CGM sensor — Medtd1, CC BY-SA 4.0, via Wikimedia Commons.

The record

Fifty-six grants, kept in time.

The full docket — every granted patent from the 1993 housing to the 2026 sealed package — laid out year by year, like a long, steady trace.

Read the record →