Patent Application
20170046610
The present invention relates to a printed radio frequency sensor structure in which a direct combination of plural sensing materials to different species of interest that lets RF sensor has capability to detect various target species at one RF sensor.
Wireless sensors are devices in which sensing electronic transducers are separated from their associated readout/display components. Wireless sensors had been applied in temperature, pressure, and pH value. It also can be found in monitoring of many gases such as volatile organic compounds, toxic industrial chemicals, and chemical warfare agents in relatively interference-free industrial and indoor environments.
However, in these practical gas sensing applications, the available wireless gas sensors are not easy to meet the sensing requirements in complex environments.
To solve the fundamental selectivity and sensitivity issues, a combination of the three key sensor system components such as sensing material, transducer, and signal generation and processing techniques was utilized.
Until now, there are several battery-free passive wireless sensing technologies based on magneto-elastic, thickness shear mode, surface acoustic wave, magnetic acoustic resonance, and resonant LCR (inductor-capacitor-resistor) transducers.
Except for LCR transducers (RFID sensor tags), most of wireless sensing technologies request extra sensor IC circuits. RFID systems have been widely used in many applications ranging from logistics, to goods tracking, access control, automatic identification of animals, and so on.
With reference to
Referring to
An embodiment of a process for the fabrication of an RFID sensor has been illustrated. They also provided methods and systems for calibration of RFID sensors used in manufacturing and monitoring systems as disclosed in U.S. Pat. No. 7,911,345. For example, they proposed a selected sensing material applied onto the RFID antenna that altered its impedance response when interest gas was adsorbed on surface of sensing materials. A complementary sensor resistor and/or capacitor was also attached across an antenna and an IC memory chip to calibrate the sensor impedance response.
A sensing material layer directly coated on surface of HF and UHF RFID antenna has been disclosed in U.S. Publication No. 20140095102. In this design, one selected sensing material was coated on one tag, which is limited to only detect one target species by one tag.
For homeland security applications, long distance RFID sensor for detection of explosives is requested. So HF RFID sensor cannot be used in such long distance application.
Due to low vapor pressure of nitro explosive gases, how to improve the sensitivity, selectivity, reading range of present RF sensors is important issue for realizing it on homeland security applications. Requirements of explosive gas sensor contains be extremely sensitive, be highly selective, and be robust & stable.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.
One aspect of the present invention is to provide a printed radio frequency sensor structure in which a direct combination of plural sensing materials to different species of interest that lets RF sensor has capability to detect various target species at one RF sensor.
Further aspect of the present invention is to provide a printed radio frequency sensor structure which has a benefit of high selectivity and sensitivity due to significant change of antenna impedance.
Another aspect of the present invention is to provide a method of preparing a RFID sensor tag which is a simple, energy-saved, and environmentally friendly.
To obtain the above aspects, a printed radio frequency sensor structure provided by the present invention contains: a substrate, a RF antenna arranged on a top surface of the substrate, and a protection layer covering on the RF antenna arranged, wherein plural sensing materials are directly introduced into a RF antenna mixture of the RF antenna, such that a change occurs on not only dielectric a constant of the sensing materials but also a resistance of the RF antenna, when target species are adsorbed on a surface of a sensing antenna.
In addition, a method of preparing a RFID sensor tag provided by the present invention contains steps of:
Preferably, the conductive sensing ink/glue consists of two parts: conductive ink/glue and the plural sensing materials.
Preferably, a conductor in the conductive ink/glue is any one of metal, carbon, conductive polymer, and their derived mixtures.
Preferably, the selected sensing material is any one of metal, carbon, polymer, organically modified species, and their derived mixtures.
With reference to
Referring to
Preferably, the conductive sensing ink/glue consists of two parts: conductive ink/glue and selected sensing materials.
Preferably, a conductor in the conductive ink/glue is any one of metal, carbon, conductive polymer, and their derived mixtures.
Preferably, the selected sensing material is any one of metal, carbon, polymer, organically modified species, and their derived mixtures.
While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.
