# US 8,786,441 B2 · Radio frequency identification tag

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- Number: US 8,786,441 B2
- Document ID: US8786441B2
- Status: Granted
- Kind: B2
- Application number: 13/307,023
- Filed: 2011-11-30
- Published: 2012-06-07
- Granted: 2014-07-22
- Earliest claimed: 2010-12-01
- Assignees: Electronics and Telecommunications Research Institute
- Applicants: Yong Suk Yang; In-Kyu You; Jae Bon Koo
- Inventors: Yong Suk Yang; In-Kyu You; Jae Bon Koo
- Web page: https://patentgrep.com/patent/US8786441B2

## CPC

- G06K 19/0723: {the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs}
- G06K 17/0029: {the arrangement being specially adapted for wireless interrogation of grouped or bundled articles tagged with wireless record carriers}
- G06K 19/07773: {Antenna details (antennas for wireless devices, e.g. RFID tags, in general H01Q1/22)}
- G06K 19/07788: {the antenna being of the capacitive type}
- G06K 19/0725: {the arrangement being a circuit for emulating a plurality of record carriers, e.g. a single RFID tag capable of representing itself to a reader as a cloud of RFID tags}
- G08B 13/2434: {Tag housing and attachment details}
- G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS

## Abstract

Provided is a radio frequency identification (RFID) tag. The RFID tags includes: a conductive layer and a conductive line disposed above and below an insulation layer, respectively; an antenna connected to one end of the conductive line; a resistor connected to the other end of the conductive line; a first conductive plate connected to the conductive line and constituting a first capacitor in conjunction with the conductive layer and the insulation layer; and a first sensing device connected between the conductive line and the conductive layer and having an impedance changed according to a sensing of a first target material.

## Claims

### Claim 1

A radio frequency identification (RFID) tag comprising:
a conductive layer and a conductive line disposed above and below an insulation layer, respectively;
an antenna connected to one end of the conductive line;
a resistor connected to the other end of the conductive line;
a first conductive plate connected to the conductive line and constituting a first capacitor in conjunction with the conductive layer and the insulation layer; and
a first sensing device connected between the conductive line and the conductive layer and having an impedance changed according to a sensing of a first target material.

### Claim 2 (depends on 1)

The RFID tag of claim 1, wherein the first conductive plate and the first sensing device are connected to the conductive line at a first point between one end and the other end of the conductive line.

### Claim 3 (depends on 1)

The RFID tag of claim 1, wherein the first sensing device comprises:
a first electrode connected to a first point of the conductive line;
a second electrode connected to the conductive line through a contact plug penetrating the insulation layer; and
a sensing material disposed between the first and second electrodes and having an impedance changed according to the sensing of the first target material.

### Claim 4 (depends on 3)

The RFID tag of claim 3, further comprising:
a first protective layer covering the conductive layer; and
a second protective layer disposed on the antenna, the conductive line, the resistor, and the first sensing device and exposing the sensing material.

### Claim 5 (depends on 4)

The RFID tag of claim 4, wherein the sensing material has a resistance value changed according to the sensing of the first target material.

### Claim 6 (depends on 4)

The RFID tag of claim 4, wherein the sensing material has a permittivity changed according to the sensing of the first target.

### Claim 7 (depends on 2)

The RFID tag of claim 2, wherein, when the first target material is not sensed by the first sensing device, impedances of the first capacitor and the first sensing device are set to allow a reflectance at the first point of the conductive line to be the maximum.

### Claim 8 (depends on 2)

The RFID tag of claim 2, wherein a distance from the antenna to the first point of the conductive line is k times (k is an integer greater than 0) of a wavelength of a radio frequency used in the RFID tag.

### Claim 9 (depends on 2)

The RFID tag of claim 2, wherein a distance from the antenna to the first point of the conductive line is k times (k is a reciprocal of the square number of 2) of a wavelength of a radio frequency used in the RFID tag.

### Claim 10 (depends on 2)

The RFID tag of claim 2, further comprising:
a second conductive plate connected to a second point of the conductive line disposed in an opposite direction of the antenna based on the first point of the conductive line and constituting a second capacitor in conjunction with the conductive layer and the insulation layer; and
a second sensing device connected between the second point of the conductive line and the conductive layer and having an impedance changed according to a sensing of a second target material.

### Claim 11 (depends on 10)

The RFID tag of claim 10, wherein, when the second target material is not sensed by the second sensing device, impedances of the second capacitor and the second sensing device are set to allow a reflectance at the second point of the conductive line to be the maximum.