Powercast Debuts Energy-Harvesting Wireless Sensor System

The sensor tags capture that transmission, and the power is then harvested for storage in either a battery or a capacitor built into the tag. The tag typically includes a microcontroller chip, and can accommodate sensors to measure, for example, light, humidity, motion or temperature. Sensor data is stored on the chip, and once enough power from the RF transmitter is accumulated, the tag transmits that information via a 2.4 GHz signal, compliant with Microchip Technology's MiWi proprietary protocol based on the IEEE 802.15.4 standard, to a Powercast Building Automation System (BAS) Gateway. The first version of the gateway comes with a USB interface, and can thus be plugged into a PC to forward data to a user's building-automation software on that user's own database. However, other versions will come with interfaces for wired BAS networks such as BACnet, Modbus, Metasys, N2 and LonWorks. The gateway can also support bidirectional communications (that is, from gateway to tag, and vice versa). To conserve power stored by those sensor tags, however, the system is designed only for one-way data transmission—that is, information sent by the sensor tag to the gateway.

Powercast's WSN-1001 wireless temperature and humidity sensor.

The gateway can receive transmissions from the sensor tag up to 120 feet away indoors, and can accommodate up to 100 sensors within its range, as well as 800 sensor points (such as humidity, light or temperature). Users can then use their own software to manage the sensor readings in order to track the conditions within their facility. Powercast provides firmware for the devices themselves, as well as the interface for data received from those devices, which can then be utilized by the back-end software.

Typically, the system is designed with a gateway at the center of a cluster of sensor tags, as well as several transmitters installed around that cluster, thereby focusing their transmission toward the center to guarantee that the most transmission is received. Sensors can be installed behind walls, within rooms and above ceilings, within a range of 120 feet on all sides of the gateway. Although the system is being used predominantly by providers of HVAC control systems for data centers, it is also designed to operate with HVAC systems in offices, hospitals, hotels, apartments or other large buildings.

In addition, Powercast's energy-harvesting technology can be adapted to recharge other types of devices, such as an iPhone, and power items such as a wireless game controller, a wireless mouse or a keyboard. However, Ostaffe says, the greatest demand is currently for HVAC controls. Because the sensor tags do not require batteries that would need to be replaced, he notes, they can be installed at permanent locations, such as inside walls, where they might be utilized to detect the presence of leaking water.

Powercast's Lifetime Power Wireless Sensor System has been deployed in pilots by two large HVAC controls companies—one in a hospital and another at a data center. An additional trial, Ostaffe reports, is being prepared by a systems integrator for refrigeration and HVAC monitoring within a hospital environment.