wearable bandage with solar cell can detect how long the user has been sunbathing

"Once a user wears one, it works automatically without further action. It can be attached to the skin like a bandage or sticker, and collects energy from human movement or from the environment, such as sunlight or body motion. The energy is stored in a small capacitor, and when the stored energy reaches a set level, the device releases it through a small vibration motor. This vibration tells the user that a certain activity level, like walking distance or sun exposure, has been reached."

"Researchers from Carnegie Mellon University and the University of California develop Hapt-Aids, a wearable bandage with a solar cell that can detect how long the user has been exposed to the sun. A device for health and activity monitoring, the attachable system is created to be small, light, and self-powered. It does not need charging, batteries, or wireless connections, as the system turns human activity into energy and uses that energy to send signals to the user."

Hapt-Aids are small, lightweight, attachable bandage devices with integrated solar cells and energy harvesters that measure accumulated energy as a proxy for user activity and sun exposure. The system collects energy from sunlight and body motion, stores charge in a capacitor, and triggers a haptic vibration when the stored energy reaches a preset level, indicating a threshold has been met. The design eliminates batteries, wireless connectivity, microcontrollers, and digital sensors by using harvested energy itself as the measurement signal, enabling purely analog, low-power circuitry. Hapt-Aids operate automatically once applied and provide simple, maintenance-free notifications for activity goals like walking distance or cumulative sun exposure.

Read at designboom | architecture & design magazine