Wiliot is a spin-out tech startup based in San Diego and Israel that has developed a small Bluetooth chip that can power itself by harvesting energy from common wireless signals. The chip can be connected directly to certain types of sensors (presumably sensors that require no or extremely little power themselves).

Of course this has fascinating implications for architectural applications, as it continues the path set by EnOcean for building controls and sensors that require neither signal nor power wiring, nor even battery power. This makes various IoT systems far more cost competitive, as you can deduct the cost of pulling AC wiring to each control/sensor point.

Wiliot is targeting mass, cheap applications like clothing tags, so presumably these sorts of BLE chips could be embedded into architectural panel systems, furniture, flooring, etc., for a wide range of sensing applications.