Welcome to another episode of Powering Wearables, a monthly web series covering topics from today’s topic—flexible batteries, to reducing battery size via lithium-ion batteries to increasing battery efficiency, and more.
In the next couple of episodes, we’ll break down the different battery options, along with the pros and cons of each. Today, we’re talking flexible batteries for medical wearables.
Wearable devices intended for a healthcare setting need to be flexible so they’re not cumbersome, especially for those worn long-term to monitor chronic conditions. Making the device itself flexible isn’t too much of a challenge, but a flexible, biocompatible battery that delivers power reliably enough for clinical performance is challenging.
Thin-film lithium-ion batteries can be millimeters thick and conform to any shape, while retaining about the same voltage and current as their bulkier ancestors. These are an excellent candidate to power wireless sensors in medical wearables—which must be active for the duration of application—because they are typically long-lasting, size-specific, and rechargeable. Just keep in mind that lithium-ion batteries, while capable of high-power applications, can become explosive when overheated or overcharged!
Another option might be to hit “control P”: using nanotube ink, the cathode tube and electrolyte components of zinc-carbon batteries can be printed as different layers under a zinc anode layer—making the battery less than a millimeter thick. The ink’s nanotubes can charge to conduct more efficiently than a conventional battery in some cases, but the discharge currents are presently under practical clinical use levels.
In the healthcare sector, the most promising avenue for flexible batteries for wearables lies in biometric-monitoring skin patches. There are already a number of these commercially available that use printed batteries, and the number of companies involved in developing biometric skin patches is rising.
Filed Under: M2M (machine to machine)