Introducing Gwen: A Battery-Free Indoor Climate Sensor Reference Design
We’ve all seen them, those oversized indoor sensors whose design is dictated entirely by the bulk of a big battery. It makes you wonder: why are these devices stuck in the past?
Over the years we’ve worked across two very different markets: smart cards and smart building systems. While their applications differ, both are shaped by the same fundamental challenges – cost, scalability, form factor, and reliability. That overlap led us to a simple question: what if indoor IoT sensors were designed with the same discipline, scalability, and efficiency as smart cards?
Gwen is our answer.
A reference design inspired by smart cards
Gwen is a battery-free indoor climate sensor that measures temperature and humidity, harvests energy from indoor light, and transmits data via Bluetooth Low Energy (BLE). Rather than a finished product, Gwen was created as a reference point – a way to explore how far sensor design can be pushed when simplicity, cost efficiency, and scalability are treated as first principles.
Designed for simplicity, scale, and low maintenance
Smart cards are produced by the billions. To operate at that scale, every component must be carefully optimized – power budgets are minimal, and cost is scrutinized down to every detail.
Gwen applies that same mindset to indoor sensing.
The device is powered entirely by ambient indoor light and stores energy in a supercapacitor rather than a battery, enabling maintenance-free operation and significantly reducing lifetime ownership costs. In testing, Gwen has operated continuously in an office environment for 12 months without a single instance of downtime. The slim form factor allows the sensor to integrate naturally into indoor environments without drawing attention or disrupting interior design.
This is made possible through collaboration across the energy harvesting ecosystem – combining indoor photovoltaic cells from Epishine, ultra-low-power energy management from e-peas, and Ligna supercapacitors.
Key characteristics of the Gwen reference design:
- Battery-free operation using indoor light
- Supercapacitor-based energy storage
- Temperature and humidity sensing
- Bluetooth Low Energy communication
- Slim, compact form factor
- Low-cost bill of materials
Rethinking indoor sensor economics
Many indoor sensors perform well today, but their design and cost limit how broadly they can be deployed. Installation effort, maintenance requirements, and visual impact become real barriers when scaling from pilot projects to thousands of devices across a building portfolio. Gwen demonstrates an alternative approach – one that prioritizes scalability, long-term reliability, and economic viability from the start.
A starting point for collaboration
Gwen is not a product. It’s a starting point for OEM partners ready to rethink traditional IoT sensor design – building sensors that make sense not only technically, but also economically and aesthetically.
Interested in collaboration or licensing the reference design? Reach out to start the conversation.
