--- title: "These metal washers are replacing smart home sensors, and they work without a single wire or battery" url: https://daily.dev/posts/these-metal-washers-are-replacing-smart-home-sensors-and-they-work-without-a-single-wire-or-battery-d7i31jw0n source_url: https://www.xda-developers.com/coin-sized-sensors-could-eliminate-smart-home-batteries-forever type: article source: "XDA Developers" published: 2026-05-24T16:34:51.940Z updated: 2026-05-24T16:35:22.989Z tags: ["tech-news", "iot"] reading_time: 5 upvotes: 2 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # These metal washers are replacing smart home sensors, and they work without a single wire or battery **[XDA Developers](https://daily.dev/sources/xda-developers)** · 5 min read · 2 upvotes · 0 comments ## Summary Georgia Tech researchers have developed passive metal washers that replace traditional battery-powered smart home sensors. Each washer has custom cutouts that produce a unique ultrasonic frequency when struck by a tab attached to a moving object like a door or drawer. A single central microphone captures these inaudible pings and triggers automations, eliminating the need for individual batteries, radios, or circuit boards in each sensor. The system requires no machine learning, offers inherent privacy since ultrasound degrades within a meter or two and cannot pass through walls, and could theoretically support up to 1,300 distinct sensor identities. Current challenges include interference from ambient high-frequency noise and line-of-sight requirements for the microphone to detect signals. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Batteries Not Included, or Required, for These Smart Home Sensors](https://daily.dev/posts/batteries-not-included-or-required-for-these-smart-home-sensors-x8uf7q5sr) · Hacker News · 1 upvotes · 0 comments - [Stop automating your schedule — use a cheap sensor to automate your actions instead](https://daily.dev/posts/stop-automating-your-schedule-use-a-cheap-sensor-to-automate-your-actions-instead-jwk84le7n) · XDA Developers · 1 upvotes · 0 comments - [Smart plugs are replacing smart appliances, and your decade-old washing machine just became future-proof](https://daily.dev/posts/smart-plugs-are-replacing-smart-appliances-and-your-decade-old-washing-machine-just-became-future-p-vbcfpckau) · XDA Developers · 34 upvotes · 9 comments - [Smart appliances are expensive, so I made my dumb ones report when they were done instead](https://daily.dev/posts/smart-appliances-are-expensive-so-i-made-my-dumb-ones-report-when-they-were-done-instead-1t4xiwpnw) · XDA Developers · 0 upvotes · 0 comments - [I connected my dumb appliances to Home Assistant, and it felt like upgrading my whole house](https://daily.dev/posts/i-connected-my-dumb-appliances-to-home-assistant-and-it-felt-like-upgrading-my-whole-house-o8oswyzsu) · XDA Developers · 0 upvotes · 0 comments --- Tags: [#tech-news](https://daily.dev/tags/tech-news), [#iot](https://daily.dev/tags/iot) [View this post on daily.dev](https://daily.dev/posts/these-metal-washers-are-replacing-smart-home-sensors-and-they-work-without-a-single-wire-or-battery-d7i31jw0n)