RF-Powered Wireless Sensors

Battery-free wireless sensors can be a reality using RF as the power source.  To demonstrate this concept, Powercast has a created prototype battery-free wireless sensor with the temperature sensor board in our Lifetime Power™ Evaluation and Development Kit.

A short clip of the sensor in action is shown below.

The prototype sensor has a dipole receiving antenna and is operating from power being broadcast by a nearby 900MHz band transmitter.  The sensor operates continuously when close to the transmitter and intermittently as it is moved further away.  The frequency of operation decreases the further it is moved away from the transmitter.   For many applications, having the sensor wake-up once a minute to transmit a reading is sufficient.

The LCD driver and display requires much more power than low power RF radios like 802.15.4, ZigBee , ULP WiFi, etc, so radio-enabled sensors will work at an even greater distance than this prototype.

Applications include perpetual, wireless powering of battery-free wireless sensors for commercial buildings, industrial facilities, and process monitoring, or unattended ground sensors for military or surveillance activities that can be activated on-demand.