In a wristwatch, imagine the battery is in the strap and there’s a medical sensor in there connected to the internet. If someone is monitoring that, they could phone up if the user has forgotten to take some medication. This could save hundreds of dollars in medical fees later. What’s missing? It’s a stable battery.

Sadoway uses a near-future vignette—an internet-connected watch strap with embedded sensors—to illustrate how energy storage, not sensing or connectivity, is often the limiting factor in wearable and medical technologies. The scenario frames batteries as an enabling infrastructure: without a safe, long-lived, and dependable power source, even compelling health-monitoring applications (like medication adherence prompts) cannot be deployed at scale or trusted in daily life. The rhetorical question “What’s missing?” underscores a recurring theme in materials science and engineering: breakthroughs in devices and data are constrained by the less glamorous problem of stable, practical energy storage.