RFID interrogation probe

Abstract

An RFID interrogation probe (1) comprises a ring shaped housing (2), having a maximum thickness (I) (measured along its cylindrical axis) which is less than the innermost diameter (di) of the housing, and a looped antenna (3) housed within the ring shaped housing.

Claims

1. A radio frequency identification (RFID) interrogation probe for interrogating RFID tagged disposable cryogenic storage containers comprising: a ring shaped housing having a length from an upper side of the housing to a lower side of the housing which is less than an innermost diameter of the ring shaped housing, the length being in an axial direction, the ring shaped housing defining an orifice adapted to encircle one or more RFID tagged cryogenic containers, and the ring shaped housing further comprising support legs mounted to the ring shaped housing; a looped antenna housed within the ring shaped housing; and an RFID reader module housed within the ring shaped housing, the RFID reader module communicably connected to the antenna for transmitting an encoded radio signal to the RFID tagged cryogenic container.

2. The RFID interrogation probe of claim 1, wherein an innermost diameter of the ring shaped housing is no less than 70 mm.

3. The RFID interrogation probe of claim 1, wherein the looped antenna includes no more than 2 loops.

4. The RFID interrogation probe of claim 1 wherein the ring shaped housing further comprises a connection component that connects the housing to a support.

5. The RFID interrogation probe of claim 4, wherein the support includes a stand or a rod.

6. The RFID interrogation probe of claim 5, wherein the connection component includes two fixing holes and wherein the ring shaped housing defines a cavity for electrical components, the cavity being located in-between the two fixing holes.

7. The RFID interrogation probe of claim 1, wherein an inner perimeter of the ring housing is circular in cross section.

8. A radio frequency identification (RFID) interrogation probe for interrogating RFID tagged disposable cryogenic storage containers comprising: a ring shaped housing having a length from an upper side of the housing to a lower side of the housing which is less than an innermost diameter of the ring shaped housing; a looped antenna housed within the ring shaped housing; and an RFID reader module communicably connected to the antenna for transmitting an encoded radio signal to the RFID tagged container, wherein the ring shaped housing further comprises a connection component that connects the housing to support legs, and wherein the ring shaped housing defines a cavity for electrical components, and wherein: the RFID reader module is located inside the cavity of the ring shaped housing; and the RFID interrogation probe further comprises matching circuitry housed within the cavity that matches the looped antenna to the RFID reader module.

9. The RFID interrogation probe of claim 8, wherein the matching circuitry comprises: a fixed capacitor, a variable capacitor, and a resistor all connected to each other in parallel.

Description

(1) The present invention will now be disclosed by way of example only, with reference to the accompanying figures, in which:

(2) FIG. 1a is a plan view of an RFID probe according to the present invention and FIG. 1b shows a cross section of the RFID probe along line A-A as shown in FIG. 1a;

(3) FIG. 2 is a schematic diagram of the looped antenna and connecting circuitry of the RFID probe;

(4) FIG. 3 is a picture of the ring shaped housing of the probe, the ring shaped housing having two halves;

(5) FIG. 4 is a picture of the housing of FIG. 3 with the two halves separated;

(6) FIG. 5 is a perspective view of the RFID probe in combination with a stand; and

(7) FIG. 6 is a picture of a rod for attachment to the RFID probe.

DESCRIPTION

(8) FIGS. 1a and 1b show an RFID probe 1 having a ring shaped housing 2 which houses a looped antenna (not shown). The length of the ring shaped housing 1 along its cylindrical axis is less than the outermost diameter d.sub.o of the housing. The length of the ring shaped housing 1 is also less than the innermost diameter d.sub.i of the housing.

(9) The ring shaped housing 2 includes connection means 4 in the form of fixing holes. The fixing holes are bored holes which extend from one side of the housing to the other.

(10) The ring shaped housing 2 also includes a cavity 5 which can be used to house electronics such as matching circuitry that matches the looped antenna to a coaxial cable and therefore to an RFID reader that is at the far end of the coaxial cable. In this way, the design enables the RFID probe to be placed into a cold environment (such as a Dewar or a transport flask filled with liquid nitrogen) whilst keeping the reader electronics outside of the cold environment (e.g. wand lowered into Dewar, or at the mouth of a small transport flask containing liquid nitrogen).

(11) Alternatively, a complete RFID reader could be housed in the cavity. Such a design would be particularly useful where the RFID probe is to be used in temperatures of around 40 C. and above.

(12) The looped antenna 3 of the RFID probe 1 is shown in more detail in FIG. 2.

(13) In the embodiment shown in FIG. 2, the antenna coil of the looped antenna has 2 turns. The diameter of looped antenna is 80 mm and the copper wire used to form the antenna has a 0.75 mm diameter giving an antenna coil inductance of about 2 H.

(14) The looped antenna 3 is connected to a coaxial cable 8 via a matching circuit and a coaxial connector 7. The matching circuit is made up of: a fixed capacitor (C.sub.F) 6, a variable capacitor (C.sub.V) 16 and a resistor (R) 17 all connected to each other in parallel.

(15) In the embodiment shown in FIG. 2, the resistor R has a fixed value of 60 ohms, the fixed value capacitor (C.sub.F) 6 has a value of around 150 pf (picofarads) and the variable capacitor C.sub.V is variable over a range of 10 pf to 50 pf so that it can be set to match the RFID probe antenna to the coaxial cable 8 and therefore to an RFID reader module located at the far end of coaxial cable 8.

(16) The function of the resistor 17 is to form part of the matching circuitry but also to provide the required circuit bandwidth (Q factor) in order to allow the standard RFID transmit and receive data bandwidth to propagate through to the looped antenna.

(17) The parameters described above are those which have been chosen to optimise antenna performance for an antenna 3 having only 2 coils.

(18) The antenna may be made up of any number of coils, for example up to 10 coils, in which case different values of the fixed capacitor 6, variable capacitor 16 and fixed resistor 17 would be chosen in order to optimise antenna performance for the given number of coils.

(19) FIGS. 3a, 3b and 4 show a ring shaped housing 2 formed of two halves 2a, 2b. FIGS. 3a and 3b show the two halves in an assembled configuration.

(20) As shown in FIG. 3a, the first half of the housing 2a is placed on top of the second half of the housing 2b to form a hermetically sealed interface 9. The hermetically sealed interface can be achieved by a welding type adhesive.

(21) Fixing means 15 such as nuts and bolts inserted into fixing holes 4a, 4b also act to hold the two halves 2a 2b of the ring shaped housing together.

(22) Each half 2a, 2b of the ring shaped housing 2 has a circular inner profile and a rectangular outer profile.

(23) FIG. 4 shows the two halves 2a and 2b of the ring shaped housing in an unassembled configuration.

(24) Each half includes connection means in the form of two fixing holes 4a, 4b bored through the housing 2a, 2b. In addition, each half of the housing defines a cavity half 5a, 5b. The cavity halves 5a, 5b match up to form the cavity 5 when the two halves of the housing are assembled together. The fixing holes 4a, 4b of each half are located either side of cavity halves 5a and 5b.

(25) Each half of the housing 2a, 2b also includes a track 11a, 11b to receive the looped antenna. The track enables the two halves 2a, 2b to be assembled around the looped antenna 3 to create a seal.

(26) FIG. 5 shows the RFID probe 1 mounted on a stand 12. The stand is L-shaped and is attached to the RFID probe 1 at connection means 4 using fixing means such as screws or bolts. When mounted on a stand 12, the RFID probe can be mounted on a surface such as a laboratory bench. This arrangement is particularly useful when the probe is used to write (i.e. to program) RFID tagged disposable containers.

(27) FIG. 6 shows a rod 13 on which the RFID probe 1 can be mounted. fixing means 15 such as screws or bolts can be used to fasten the rod to the RFID probe. In this arrangement, the rod 13 can be used to lower the RFID probe into a Dewar so that RFID tagged containers can be read whilst inside the Dewar. The rod 13 includes a handle 14.

(28) The rod 13 and/or the handle 14 may be made of a thermally insulating material to avoid undesirable heat transfer between the rod and the Dewar.

(29) The RF coaxial cable can be simply plugged into an RF port standard RFID reader, that is, a port for transmitting and receiving the 13.56 MHz carrier frequency. The RFID reader can then be connected to a processor/PC.

(30) The RFID probe of the present invention can be used in the writing of RFID tags and/or the reading of RFID tags by sending appropriate signals to the looped antenna 3.

(31) Assuming that the transmitted power of the reader electronics is chosen appropriately, the small maximum length along the cylindrical axis relative to the innermost diameter of the antenna coils enables any unwanted exciting (transmitted) field outside the probe to be kept low whilst the field inside the hole of the probe is high enough to activate RFID tags. In this way, the need for extra shielding of the antenna is minimised.

(32) The foregoing description of the preferred embodiments of the invention have been presented for purposes of illustration and description, it is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings.

(33) It is intended that the scope of the invention be defined by the claims appended hereto.