Tired of the irritating beeping noise when your carbon monoxide detector’s battery is low? Soon that could be a thing of the past with your iPhone and/or Apple Watch detecting and alerting you to dangerous gases.
Apple has applied for a patent (number 20190025271) for “chemically robust, miniature gas sensors.” In the patent filing, Apple notes that miature gas sensors for consumer electronics represent a technology category that could enable upcoming features and/or products in applications such as, e.g., environmental and health monitoring, smart homes, and internet of things (IoT).
Chemical poisoning and deactivation of the sensor materials in metal oxide sensors, however, can cause drift in both baseline resistance and sensitivity. This can lead to grossly inaccurate sensing performance and even premature device failures. Such drift and failure modes vary based on the operation and ambient environment; making global predictive software compensation to drift rather difficult.
Various chemical species from the environment including siloxanes, sulfates, chlorides and phosphates have been identified as high-risk poisons. In addition, humidity (e.g., water vapor) can be a major interfering species that can reduce metal oxide sensor accuracy. Chemical poisoning and sensor drift pose great challenges to the mass market adoption of miniature gas sensors. Apple thinks it has a solution: integrating the gas sensor into a smartphone or smartwatch.
Here’s a summary of the invention: “A miniature gas sensing device includes a silicon-based substrate embedded with multiple first heating elements. A number of electrodes are disposed on the silicon-based substrate. A gas-sensing layer covers the electrodes. A porous or mesoporous adsorbent layer selectively filters components of a gas mixture other than a target gas and allows the target gas to reach the gas-sensing layer. The first heating elements are operable to periodically regenerate sensing capabilities of at least the gas-sensing layer.”
Of course, Apple files for — and is granted — lots of patents by the U.S. Patent & Trademark Office. Many are for inventions that never see the light of day. However, you never can tell which ones will materialize in a real product.