Sensor Dogbone

March 16, 2015

First passive UHF moisture-sensing inlay on the market

Driven by innovation and responsiveness to customer requirements, Smartrac has launched the new Sensor Dogbone™. It is designed primarily to measure moisture conditions in harsh industrial environments such as construction, energy, healthcare, automotive production and the military.

The first such sensor inlay on the market, Smartrac Sensor Dogbone is a passive UHF single-chip sensor solution that offers cost-efficiency, is easy to implement, and works on both low- and high-dielectric materials like cardboard, plastics, stone, wood and construction materials. It is deployable where active or semi-active sensors are not practical, and involves no battery maintenance, costs or problems with product lifetime or recycling.

Introducing new features to the company’s inlay and tag product range, this RFID sensor is based around a passive UHF inlay equipped with RFMicron’s Magnus(R)S IC. The inlay offers great performance, and accurately detects and measures moisture levels in the surrounding environment. The sensing information is digitized and wirelessly communicated to off-the-shelf readers using a standard UHF Gen 2 protocol READ command for further processing.

Advanced antenna design for better read range
Sensor Dogbone also features leading-edge antenna design. The antenna acts as a resistor/inductor/capacitor (RLC) tuned circuit. Any one of these, or any combination of the three, can be exploited to enable an antenna to sense its environment. The antenna converts environmental data into an impedance change, and then the sensor tag IC translates this into a sensor code, as it dynamically matches antenna impedance to die impedance.

Traditional sensors exploit changes in resistance to measure environmental variables, but this results in reduced tag read range due to power dissipated in the resistance. Sensor Dogbone’s ability to use inductance or capacitance means that read range issues can be avoided.

Virtually unlimited applications beyond moisture sensing
When configured as a moisture sensor, Sensor Dogbone measures the presence of water when the tag’s environment becomes wet. The interdigitated capacitor experiences a significant change in capacitance, when it changes from dry to wet; the dipole antenna registers an impedance change depending on the amount of water on the capacitor; and the sensor tag IC converts this into a code that indicates the amount of water present.

However, moisture sensing is only one potential application. The product’s application space is virtually unlimited, since any physical effect that affects capacitance, inductance, resistance or antenna loading can be exploited to produce a new, customized sensor tag to sense specific environmental conditions.

Sensor Dogbone

Passive UHF RFID sensor inlays can expand reach of Internet of Things
The benefits derived from the Internet of Things (IoT) will accelerate as it becomes more widespread. One element necessary to facilitate an ubiquitous IoT is a sensor technology that allows the deployment of large numbers of sensors that are wireless, maintenance-free, and inexpensive enough for use almost anywhere. The passive UHF RFID Sensor Dogbone fits this bill perfectly.

A second required element is some kind of integration services layer that makes it easy for independent software developers and enterprise IT departments to leverage the full potential of RFID technology, without having to invest in expensive and complex IT infrastructure and middleware. Ideally, the integration services should comprise a minimum function set to ensure the seamless and efficient deployment of innovative RFID sensor-based solutions:

  1. A repository of all RFID sensor tag-related data, e.g. sensor range and calibration data, that can be accessed securely by authorized web services and apps; 
  2. A repository of measurement data related to the sensor-tagged physical object;
  3. A decision flow engine, e.g. so that if an RFID sensor-tagged object exceeds a preset moisture level, an alarm is sent by SMS/email to a service technician.

The Smartrac Sensor Dogbone meets the most demanding industry requirements, and represents the state of the art in passive RFID sensing suitable for high-volume production. The passive UHF sensor inlay offers significant possibilities to enhance production control, quality control and maintenance in many different applications. It can be delivered in dry, wet and label format to suit all converting-industry needs, and complies with all relevant industry standards and strict quality control parameters.

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