Radio-Frequency IDentification (RFID) is a technology that provides automatic identification of objects, and relies on storing and remotely retrieving data using devices called RFID tags or transponders. The RFID tag is an object that can be applied to and/or incorporated into a product, animal, or person for the purpose of identification using radio waves. Some tags can even be read from several meters away and beyond the line of sight of the reader. Generally, there are three varieties of RFID tags: passive, active, or semi-passive (also known as battery-assisted). Passive tags require no internal power source, are powered by harvesting energy from various artificial energy sources and/or natural energy sources (such as voice signals, other electromagnetic waves, sunlight, vibrations, or RF noise), and are only active when a reader is nearby to power them; semi-passive and active tags require a power source to function (usually a small battery).

Recent industry standardization activities in defining communication methods and data formats for transducers (sensors and actuators) communicating with RFID tags indicated an emerging trend of combining RFID into sensors and/or sensor-enhanced RFID tags to maximize the use of a wide variety of applications for detection, identification, and tracking purposes. In support of this trend, capabilities enabled with the battery-free passive voice-enabled RFID smart sensor technology include identification, tracking, detection, diagnostic, and other networking capabilities for remote monitoring and control.

The technology developed was a passive voice-enabled RFID device, a smart system that includes a power harvesting circuit that converts energy sources to voltage and current to power the device without the need of a battery. This smart system recognizes a few voice commands, and this capability could enhance facility security when implemented in a smart badge.

Unique features of this passive voice-enabled RFID design system include the following: (1) RF harvesting technology to supply working voltage; neither a battery nor AC power is required; (2) the capability of enabling plug-and-play sensor distributions in harsh operating environments; (3) support for distributed sensor networks without battery replacement issues; (4) system-on-chip (SoC) technology to integrate the microprocessor, memory, analog-to-digital convert (ADC), and RF on a single chip, hence reducing costs while increasing productivity; (5) reduction in installation, maintenance, and upgrade costs of the sensor network and systems; and (6) additionally, its potential future application as an integral component of a smart badge.

Smart sensor technology like the one developed will enable a variety of applications, and the combination of tracking and identifying objects creates great opportunities to provide ambient DIaK (Data, Information and Knowledge) and extended tracking services, applications, energy control, security monitoring, and integrated health monitoring.

This work was done by Ray Wang of Mobitrum Corporation for Stennis Space Center. For more information, contact Ray Wang, This email address is being protected from spambots. You need JavaScript enabled to view it., or

Mobitrum Corporation,
6875 Churchill Road,
McLean, VA 22101.

Refer to SSC-00380.

NASA Tech Briefs Magazine

This article first appeared in the August, 2015 issue of NASA Tech Briefs Magazine.

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