WO2014135920A1

WO2014135920A1 - An apparatus configured to switch a transmission power regulator of an rfid sensor device

Info

Publication number: WO2014135920A1
Application number: PCT/IB2013/051738
Authority: WO
Inventors: Michael Robert Astley; Stefano BORINI; Jani Kivioja; Teuvo Tapani RYHÄNEN; Di Wei
Original assignee: Nokia Corporation
Priority date: 2013-03-05
Filing date: 2013-03-05
Publication date: 2014-09-12

Abstract

An apparatus configured to switch a transmission power regulator of an RFID sensor device between on and off states, the transmission power regulator configured to regulate the supply of power from a power supply (101) of the RFID sensor device to a transmission amplifier (213) of the RFID sensor device, wherein the on state allows for transmission of RFID sensor data from the RFID sensor device as an outgoing radio-frequency signal by regulating the supply of power to the transmission amplifier to amplify the outgoing radio-frequency signal.

Description

An apparatus and associated methods Technical Field

The present disclosure relates to the field of RFID sensors, associated methods and apparatus, and in particular concerns an apparatus configured to switch a transmission power regulator of an RFID sensor device between on and off states. Background

It would be advantageous to combine low power consumption and low cost with long range wireless transmission in radio-frequency identification (RFID) sensors. The achievement of such a combination is a technological challenge, however.

The apparatus and methods disclosed herein may or may not address this issue.

The listing or discussion of a prior-published document or any background in this specification should not necessarily be taken as an acknowledgement that the document or background is part of the state of the art or is common general knowledge. One or more aspects/embodiments of the present disclosure may or may not address one or more of the background issues.

Summary

According to a first aspect, there is provided an apparatus configured to switch a transmission power regulator of an RFID sensor device between on and off states, the transmission power regulator configured to regulate the supply of power from a power supply of the RFID sensor device to a transmission amplifier of the RFID sensor device, wherein the on state allows for transmission of RFID sensor data from the RFID sensor device as an outgoing radio-frequency signal by regulating the supply of power to the transmission amplifier to amplify the outgoing radio-frequency signal.

The apparatus may be configured to switch the transmission power regulator from the off state to the on state when transmission of RFID sensor data is required (e.g. based on an appropriate received indication). The apparatus may be configured to switch the transmission power regulator from the on state to the off state when transmission of RFID sensor data is not required (e.g. based on an appropriate received indication). The apparatus may be confrgured to switch the transmission power regulator from the off state to the on state periodically, in response to a request for RFID sensor data and/or when the RFID sensor data reaches a predefined threshold value.

The apparatus may be configured to switch the transmission power regulator between the on and off states by providing signalling to the transmission power regulator to place the transmission power regulator in the on state or off state.

The apparatus may be configured to switch the transmission power regulator between the on and off states by respectively making and breaking an electrical connection between the power supply and transmission power regulator. The apparatus may be configured to operate a switch to make and break the electrical connection between the power supply and transmission power regulator.

The apparatus may comprise a processor and memory including computer program code, the memory and computer program code configured to, with the processor, switch the transmission power regulator between the on and off states.

The apparatus may comprise one or more logic gates configured to switch the transmission power regulator between the on and off states.

The transmission power regulator may be configured to regulate the supply of power from a power supply of the RFID sensor device to a reception amplifier of the RFID sensor device. The on state of the transmission power regulator may allow for reception of data at the RFID sensor device as an incoming radio-frequency signal by regulating the supply of power to the reception amplifier to amplify the incoming radio-frequency signal. The data received at the RFID sensor device may comprise a request for RFID sensor data from a remote device.

The off state of the transmission power regulator may be a low power mode (e.g. sleep mode) of the transmission power regulator. The on state of the transmission power regulator may be a high power mode (e.g. active mode) of the transmission power regulator. The transmission power regulator may be configured to consume no more than 1 μ\Λ/ of power in the off state. Regulating the supply of power from the power supply to the transmission amplifier may comprise delivering up to 2W of power from the power supply to the transmission amplifier. Additionally or alternatively, regulating the supply of power from the power supply to the transmission amplifier may comprise delivering up to 1A of current to the transmission amplifier.

The apparatus may comprise one or more of the transmission power regulator, the power supply and the transmission amplifier. The power supply may have a power density of at least 100W/kg. The power supply may comprise one or more supercapacitors. The power supply may comprise a storage element and a harvesting element configured to generate power for storage by the storage element. The transmission amplifier may be a power amplifier.

The apparatus may comprise a sensor power regulator configured to regulate the supply of power from a power supply of the RFID sensor device to an RFID sensor of the RFID sensor device to enable generation of the RFID sensor data by the RFID sensor. The transmission power regulator and sensor power regulator may be configured to regulate the supply of power from a common power supply. The sensor power regulator may be configured to consume no more than 10μ\Λ/ of power in usage. The apparatus may comprise one or more of a reception amplifier configured to allow for reception of data at the RFID sensor device as an incoming radio-frequency signal by amplifying the incoming radio-frequency signal, and an RFID sensor configured to generate the RFID sensor data. The reception amplifier may be a low-noise amplifier. The RFID sensor may be configured to sense one or more of temperature, relative humidity and geographic location.

The data which is transmitted and/or received by the RFID sensor device may be transmitted at a frequency of between 100kHz and 10GHz. In particular, the data may be transmitted at a frequency of 865-868MHz (UHF in Europe) or 902-928MHz (UHF in the US). The apparatus may be the RFID sensor device or a module for the RFID sensor device.

According to a further aspect, there is provided a method comprising switching a transmission power regulator of an RFID sensor device between on and off states, the transmission power regulator configured to regulate the supply of power from a power supply of the RFID sensor device to a transmission amplifier of the RFID sensor device, wherein the on state allows for transmission of RFID sensor data from the RFID sensor device as an outgoing radio-frequency signal by regulating the supply of power to the transmission amplifier to amplify the outgoing radio-frequency signal.

The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated or understood by the skilled person. Corresponding computer programs (which may or may not be recorded on a carrier) for implementing one or more of the methods disclosed herein are also within the present disclosure and encompassed by one or more of the described example embodiments.

The present disclosure includes one or more corresponding aspects, example embodiments or features in isolation or in various combinations whether or not specifically stated (including claimed) in that combination or in isolation. Corresponding means for performing one or more of the discussed functions are also within the present disclosure. The above summary is intended to be merely exemplary and non-limiting. Brief Description of the Figures

A description is now given, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 shows an RFID sensor device;

Figure 2 shows greater detail of the front end of the RFID sensor device;

Figure 3a shows one embodiment of an apparatus configured to switch the transmission power regulator of the RFID sensor device between on and off states; Figure 3b shows another embodiment of an apparatus configured to switch the transmission power regulator of the RFID sensor device between on and off states; Figure 4a shows the power of a radio-frequency signal from an RFID tag at an RFID tag reader as a function of the distance between the RFID tag and the RFID tag reader; Figure 4b shows the power of a radio-frequency signal from an RFID tag reader at an RFID tag as a function of the distance between the RFID tag reader and the RFID tag; Figure 5 shows one method of fabricating the RFID sensor device;

Figure 6 shows the main steps of a method of using the apparatus of Figure 3; and Figure 7 shows a computer-readable medium comprising a computer program configured to perform, control or enable the method of Figure 6.

Description of Specific Aspects/Embodiments

RFID is the use of a wireless non-contact system that uses radio-frequency electromagnetic fields to transfer data from an RFID tag attached to an object to an RFID tag reader for the purposes of automatic identification and tracking. The tag contains electrically stored information which may be read from up to several meters away. Unlike a bar code, the tag does not need to be within the line of sight of the reader and may be embedded within the tracked object.

RFID tags can be passive, active or semi-active. An active tag has an on-board battery and periodically transmits its ID signal, a semi-active has a small battery on board and is activated when in the presence of a RFID reader, and a passive tag uses the radio energy transmitted by the reader as its energy source. A passive tag is typically cheaper and smaller than an active or semi-active tag because it has no battery, but the reader must be in close proximity to the tag in order for the RF field to be strong enough to transfer sufficient power to the tag.

RFID technology has recently been used in combination with sensors to enable sensor data to be read from the sensors in the same way as identification information is read from RFID tags. As with RFID tags, RFID sensors may be passive, active or semi- active. Passive and semi-active RFID sensors are low cost RFID sensors with a relatively short wireless communication range (e.g. up to 1m). Active RFID sensors are able to transmit over a longer range, but tend to be more expensive and bulkier than passive or semi-active RFID sensors (e.g. they cannot be formed as stickers like low cost passive tags). It is also impractical to periodically replace batteries for active sensors in applications involving hundreds or thousands of distributed sensors (e.g. in large factories). As mentioned in the background section, it would be advantageous to combine low power consumption and low cost with long range wireless transmission in RFID sensors, but this has proven to be a technological challenge.

Active RFID devices may use a "range extender" to increase the distance between the device and reader. Range extenders typically consist of an additional front-end circuit which features a power amplifier and a low-noise amplifier to improve the transmission power and reception sensitivity, respectively. Such amplifiers require a relatively large power, however, and are therefore only suitable for use with actively powered tags. There have been reports on the use of RFID technology with self-powered wireless temperature sensors. For example, a low power consumption CMOS temperature sensor has been integrated into a passive RFID tag. This device eliminates the need for a separate power supply, but the reading distance is limited because it uses inductive coupling to transmit the power from the reader to the transponder to power up the circuit. A self-powered RFID sensing system for structural health monitoring has also been reported which couples an RFID transponder directly to a piezoelectric arrangement. In this system, the piezoelectric arrangement is attached to a building structure to convert kinetic energy provided by the structure into electrical energy usable for powering the RFID transponder and to generate sensing information regarding the state of the structure.

The present application relates to an RFID sensor device which is capable of transmitting and receiving data over a distance of up to 100m, for example, in the described embodiments. As will be described in more detail later, the device may be fabricated in a cost-effective manner and consumes relatively little power.

The RFID sensor device is shown in Figure 1 and comprises a power supply 101 , an RFID sensor 102, an analogue front end 103, an antenna 104, a power management circuit 105 and a control apparatus 106 for the power management circuit 105. The power supply 101 comprises a storage element 107 (in this example, a stack of supercapacitors) and a harvesting element 108 (in this example, a piezoelectric element) configured to generate power for storage by the storage element 107. The power supply 101 has a power density of at least 100W/kg to provide an instantaneous and intense power burst which can be used to increase the range of the radio communications.

The RFID sensor 102 may be any type of sensor (e.g. an environmental sensor such as a humidity and/or temperature sensor) and comprises a sensor element 109, a sensor interface 110, a microcontroller unit (MCU) 111 and a radio interface 112. The RFID sensor 102 is configured to generate sensor data for radio transmission to another device/apparatus (such as an RFID tag reader, a computer or a mobile phone).

The analogue front end 103, shown in greater detail in Figure 2, comprises a transmission amplifier 213 (e.g. a power amplifier) configured to amplify outgoing radio- frequency signals to allow for transmission of the RFID sensor data from the RFID sensor device, and a reception amplifier 214 (e.g. a low-noise amplifier) configured to amplify incoming radio-frequency signals to allow for reception of data at the RFID sensor device. The data received at the RFID sensor device may comprise a request for RFID sensor data from a remote device (such as an RFID tag reader, a computer or a mobile phone). As shown in Figure 2, the transmission 213 and reception 214 amplifiers are switched into the circuit at different times depending on whether the RFID sensor device is transmitting or receiving data.

The antenna 104 is configured to transmit outgoing radio-frequency signals received from the transmission amplifier 213 and receive incoming radio-frequency signals from remote devices for passing to the reception amplifier 214.

The power management circuit 105 comprises at least two separate power regulators: a transmission power regulator 115 configured to regulate the supply of power from the power supply 101 to the transmission 213 and reception 214 amplifiers to respectively enable transmission and reception of data by the RFID sensor device; and a sensor power regulator 1 16 configured to regulate the supply of power from the power supply 101 to the RFID sensor 102 to enable generation of the RFID sensor data by the RFID sensor 102. In this example, the power regulators 115, 116 are DC/DC converters configured to convert the power supply voltage (e.g. 20V) to two 3V power rails, but other buck topology switching regulators may be used instead. Given that the maximum transmission power of an RFID system is limited by law to 1W (effective radiated power (ERP)) in the US and 2W (ERP) in Europe, regulation of power from the power supply 101 to the transmission 213 or reception 214 amplifiers may be considered to comprise delivering up to 2W of power to the transmission 213 or reception 214 amplifiers. It should be noted here that the <2W of power delivered by the transmission power regulator 115 to the transmission 213 or reception 214 amplifiers is not necessarily the effective radiated power (which includes the effects of both transmission line/connector losses and the antenna gain). Furthermore, although Figure 1 shows both regulators 115, 116 being used to regulate power from a single common power supply 101 , they could be used to regulate power from respective power supplies.

The use of transmission 213 and reception 214 amplifiers, together with a high density power source 101 , is what allows the RFID sensor device to operate at long range. The use of such high power components, however, requires careful power management in order to keep the overall power consumption of the RFID sensor device to a reasonable level and to ensure that each of the electrical components has the necessary power as it is needed. The power management circuit 105 and associated control apparatus 106 (see below) help to address this issue.

The transmission power regulator 115 can be switched between distinct "on" and "off states. The on state is a high power mode in which the transmission power regulator 115 provides power to the transmission 213 or reception 214 amplifier, whilst the off state is a low power mode in which the transmission power regulator 115 does not provide power to the transmission 213 or reception 214 amplifier. The transmission power regulator 115 may consume up to 100μ\Λ/ of (quiescent) power in the on state (i.e. it is a high power regulator), but is specifically configured to consume no more than 1 pW of (quiescent) power in the off state. The sensor power regulator 116, on the other hand, operates continually in an "on" state in which it provides power to the RFID sensor 102. Since the sensor power regulator 116 is always on, it is specifically configured to consume no more than 10pW of (quiescent) power in usage (i.e. it is a low power regulator).

In order to manage the power effectively, the control apparatus 106 is configured to switch the transmission power regulator 115 from the off state to the on state when transmission of RFID sensor data is required, and is configured to switch the transmission power regulator 115 from the on state to the off state when transmission of RFID sensor data is not required. As shown in Figure 3a, the control apparatus 306 may comprise a processor 317 and memory 318 including computer program code, the memory 318 and computer program code configured to, with the processor 317, switch the transmission power regulator 115 between the on and off states. The processor 317 may be a general purpose processor dedicated to executing/processing information in accordance with instructions stored in the form of computer program code on the memory 318. The memory 318 (not necessarily a single memory unit) is a computer readable medium (e.g. comprising one or more of solid state memory, a hard drive, ROM, RAM and/or Flash) that stores computer program code. This computer program code stores instructions that are executable by the processor 317, when the program code is run on the processor 317. The internal connections between the memory 318 and the processor 317 can be understood to, in one or more example embodiments, provide an active coupling between the processor 317 and the memory 318 to allow the processor 317 to access the computer program code stored on the memory 318. Additionally or alternatively, the control apparatus 306 may comprise one or more logic gates 319 (e.g. as a state machine or sequencer) configured to switch the transmission power regulator 115 between the on and off states, as shown in Figure 3b.

In one embodiment, the control apparatus 306 is configured to switch the transmission power regulator 115 between the on and off states by providing control signaling to the transmission power regulator 115 to specifically place it in the on state or the off state. The control signaling could be generated at predetermined intervals or based on a specific requirement to send/receive data via the antenna 104/front end 103. In another embodiment, the control apparatus 306 is configured to switch the transmission power regulator 115 between the on and off states by respectively making and breaking an electrical connection between the power supply 101 and transmission power regulator 115. In the latter embodiment, the control apparatus 306 may be configured to operate a switch 120 to make or break the electrical connection between the power supply 101 and transmission power regulator 115. Depending on the type of RFID sensor device, for example, the transmission of RFID sensor data may be required periodically, in response to a request for RFID sensor data and/or when the RFID sensor data reaches a predefined threshold value. For example, if the RFID sensor device is being used to monitor the temperature of a factory, it may be configured to transmit the current factory temperature to a temperature control unit once every 5 minutes, it may be considered to transmit the current factory temperature data to the factory manager's mobile phone in response to a request received from the mobile phone, or it may be configured to transmit a warning signal (with or without the current factory temperature) to the factory manager's mobile phone if the factory temperature exceeds a predefined temperature.

By switching the transmission power regulator 115 from the on state to the off state, the maximum power consumption of the transmission power regulator 115 drops from ~100μ\Λ/ to ~1pW. In some embodiments, the RFID sensor 102 may also be placed in an off state (e.g. low power mode) until transmission of RFID sensor data is required. In this scenario, the RFID sensor 102 may be activated and used to generate RFID sensor data periodically and/or in response to a request for RFID sensor data. The RFID sensor data can then be passed to the transmission amplifier 213 and antenna 104 for transmission. This feature therefore provides a further (albeit smaller) power saving on top of that associated with the off state of the transmission power regulator 115.

These power savings allow a greater proportion of the power generated by the harvesting element 108 to be used in charging the storage element 107 for subsequent transmission bursts. To put this into perspective, the RFID sensor device may only consume ~15pW of power when the RFID sensor 102 and transmission power regulator 115 are in the off state (low power mode). Assuming that the harvesting element 108 is used to charge the storage element 107 at a constant power of 100μ\Λ/ (which is reasonable for a piezoelectric material or solar cell), this leaves ~85μ\Λ/ of power for charging the storage element 107.

If the RFID sensor 102 and transmission power regulator 115 are only in the on state (high power mode) when transmission of RFID sensor data is required, the total energy used by the RFID sensor device during this time is estimated to be ~1.2mJ. This estimation assumes that the sensing and transmission operations respectively consume no more than 100pJ and 1 mJ, and that the transmission 115 and sensor 116 power regulators each operate at ~90% efficiency.

Supercapacitors typically have a very high capacitance (~1 F) but are limited to ~1V per capacitor. When the voltage is distributed over a stack of 20 capacitors, the effective capacitance is ~50mF resulting in an energy storage of ~10J when the stack is charged to 20V. The ~1.2mJ of energy consumed when the RFID sensor device in the on state is therefore very small in comparison to the energy stored when the RFID sensor device is in the off state. Given the charging rate of 85pJ/s (85μνν) when the RFID sensor device is in the off state, this means that the device could be used to transmit RFID sensor data at a range of up to 100m once every ~15s.

An advantage of the apparatus and methods disclosed herein is the relatively large power that can be used during radio communications compared to existing RFID sensor devices. The range of an RFID device is limited both by transmission and reception.

With existing systems, the radio transmission is limited to a few tens of mW. Since the reading range of a UHF or microwave transponder is governed by an inverse square law (the Friis transmission equation), increasing the transmission power by a factor of 25-100 increases the reading range by 5-10 times. This is illustrated in Figure 4a, which shows the power of a radio-frequency signal from an RFID tag at an RFID tag reader as a function of the distance between the RFID tag and the RFID tag reader both with (solid line) and without (dashed line) the use of a 15dB power amplifier 213 at the RFID tag. For reception, the power of the incoming radio-frequency signal must be greater than the sensitivity of the receiver at the RFID tag reader (in this case around -40dBm as indicated by the circles). As can be seen from Figure 4a, the power of the signal is greater than the sensitivity of the receiver at a distance of up to ~47m when the power amplifier 213 is used compared with a distance of up to ~8m when the power amplifier 213 is not used.

Furthermore, the receiver sensitivity of existing systems tends to be poor because very little power is available for the initial amplification stage. By increasing the available power, a high quality low-noise amplifier 214 can be inserted into the signal chain. Low- noise amplifiers 214 have a relatively large current drive (and thus a much lower noise figure), so the sensitivity of the receiving channel is improved. This is illustrated in Figure 4b which shows the power of a radio-frequency signal from an RFID tag reader at an RFID tag as a function of the distance between the RFID tag reader and the RFID tag. The sensitivity of the receiver at the RFID tag is shown by the circles both with (right- hand circle) and without (left-hand circle) the use of a 15dB low-noise amplifier 214 at the RFID tag. As can be seen, the receiver sensitivity is around -15dBm without the low- noise amplifier 214 and around -30dBm with the low-noise amplifier 214. For reception, the power of the incoming radio-frequency signal must be greater than the sensitivity of the receiver at the RFID tag. From this figure, the power of the signal is greater than the sensitivity of the receiver at a distance of up to ~47m when the low-noise amplifier 214 is used compared with a distance of up to ~8m when the low-noise amplifier 214 is not used.

The RFID sensor device described herein may be fabricated at relatively low cost using printing techniques in a roll-to-roll process. Figure 5 shows one possible implementation of the RFID sensor device.

The RFID sensor itself may comprise a sensor element 509 coupled to the RFID chip 522 of a standard RFID tag 523. The RFID sensor, power management circuit 505 and front end 503 may be made using integrated circuits and attached to the surface of the tag 523 using conductive epoxy. The antenna 504, together with the signal and power tracks, could be printed onto the tag 523 as a conductive ink (such as silver or copper ink), and the sensor element 509 could be a printed onto the tag 523 as a thin film (e.g. based on a sensitive polymer or inorganic oxide such as polyaniline or graphene oxide if it is a humidity sensor).

The energy harvesting element 508 may be a piezoelectric element which is either printed onto the tag 523 or printed onto another substrate 524 and subsequently laminated to the tag 523. Suitable piezoelectric harvesting materials include polymers such as PVdF and inorganics such as lead zirconate titanate. Alternatively, the energy harvesting element 508 may be a photovoltaic element (such as a Si-based solar cell, a thin film solar cell, an organic solar cell or a dye-sensitised solar cell) or a thermoelectric element (such as a "sandwich" including an array of n and p-type semiconductor legs). In the latter scenario, the legs may be pellets of bismuth telluride or antimony telluride which are strapped together to create a series electrical connection and a parallel thermal connection, whilst the top and bottom of the module may be aluminium oxide ceramic to provide electrical insulation and good thermal conductivity. The rectifier of the energy harvesting element 508 may be made of organic polymers which are printed onto the tag 523, or silicon diodes that are attached to the tag 523 with conductive epoxy. The energy storage element 507 may be a supercapacitor stack which, like the energy harvesting element 508, could be printed onto the tag 523 or deposited onto another substrate 525 and subsequently laminated to the tag 523. Printed supercapacitors may be made from slurries of active and conductive carbon with either a conventional separator or a polymer/gel electrolyte (e.g. PEO or an ionic liquid gel electrolyte) sandwiched therebetween.

As mentioned previously, a key aspect of the present disclosure is the method of managing the power of the RFID sensor device. In particular, by placing the transmission power amplifier 115, and possibly also the RFID sensor 102, in an off state (e.g. low power mode) when transmission of RFID sensor data is not required, a substantial power saving is achieved which can be used to charge the storage element 107 for subsequent power bursts. As also mentioned, this functionality may be controlled by a processor 317 (together with a memory 318 and computer code) and/or by one or more logic gates 319.

Figure 6 illustrates schematically the main steps 626-629 of this method of operation, whilst Figure 7 illustrates schematically a computer/processor readable medium 730 providing a computer program configured to perform control or enable one or more of these method steps 626-629.

In particular, the computer program may be configured to switch a transmission power regulator 115 of an RFID sensor device between on and off states, the transmission power regulator 115 configured to regulate the supply of power from a power supply 01 of the RFID sensor device to a transmission amplifier 213 of the RFID sensor device, wherein the on state allows for transmission of RFID sensor data from the RFID sensor device as an outgoing radio-frequency signal by regulating the supply of power to the transmission amplifier 213 to amplify the outgoing radio-frequency signal.

In this example, the computer/processor readable medium 730 is a disc such as a digital versatile disc (DVD) or a compact disc (CD). In other embodiments, the computer/processor readable medium 730 may be any medium that has been programmed in such a way as to carry out an inventive function. The computer/processor readable medium 730 may be a removable memory device such as a memory stick or memory card (SD, mini SD, micro SD or nano SD).

Other embodiments depicted in the figures have been provided with reference numerals that correspond to similar features of earlier described embodiments. For example, feature number 1 can also correspond to numbers 101, 201 , 301 etc. These numbered features may appear in the figures but may not have been directly referred to within the description of these particular embodiments. These have still been provided in the figures to aid understanding of the further embodiments, particularly in relation to the features of similar earlier described embodiments.

It will be appreciated to the skilled reader that any mentioned apparatus/device and/or other features of particular mentioned apparatus/device may be provided by apparatus arranged such that they become configured to carry out the desired operations only when enabled, e.g. switched on, or the like. In such cases, they may not necessarily have the appropriate software loaded into the active memory in the non-enabled (e.g. switched off state) and only load the appropriate software in the enabled (e.g. on state). The apparatus may comprise hardware circuitry and/or firmware. The apparatus may comprise software loaded onto memory. Such software/computer programs may be recorded on the same memory/processor/functional units and/or on one or more memories/processors/functional units. In some embodiments, a particular mentioned apparatus/device may be preprogrammed with the appropriate software to carry out desired operations, and wherein the appropriate software can be enabled for use by a user downloading a "key", for example, to unlock/enable the software and its associated functionality. Advantages associated with such embodiments can include a reduced requirement to download data when further functionality is required for a device, and this can be useful in examples where a device is perceived to have sufficient capacity to store such pre-programmed software for functionality that may not be enabled by a user.

It will be appreciated that any mentioned apparatus/circuitry/elements/processor may have other functions in addition to the mentioned functions, and that these functions may be performed by the same apparatus/circuitry/elements/processor. One or more disclosed aspects may encompass the electronic distribution of associated computer programs and computer programs (which may be source/transport encoded) recorded on an appropriate carrier (e.g. memory, signal).

It will be appreciated that any "computer" described herein can comprise a collection of one or more individual processors/processing elements that may or may not be located on the same circuit board, or the same region/position of a circuit board or even the same device. In some embodiments one or more of any mentioned processors may be distributed over a plurality of devices. The same or different processor/processing elements may perform one or more functions described herein.

It will be appreciated that the term "signalling" may refer to one or more signals transmitted as a series of transmitted and/or received signals. The series of signals may comprise one, two, three, four or even more individual signal components or distinct signals to make up said signalling. Some or all of these individual signals may be transmitted/received simultaneously, in sequence, and/or such that they temporally overlap one another. With reference to any discussion of any mentioned computer and/or processor and memory (e.g. including ROM, CD-ROM etc), these may comprise a computer processor, Application Specific Integrated Circuit (ASIC), field-programmable gate array (FPGA), and/or other hardware components that have been programmed in such a way to carry out the inventive function.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole, in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that the disclosed aspects/embodiments may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the disclosure. While there have been shown and described and pointed out fundamental novel features as applied to different embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods described may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. Furthermore, in the claims means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

Claims

1. An apparatus configured to switch a transmission power regulator of an RFID sensor device between on and off states, the transmission power regulator configured to regulate the supply of power from a power suppty of the RFID sensor device to a transmission amplifier of the RFID sensor device, wherein the on state allows for transmission of RFID sensor data from the RFID sensor device as an outgoing radio- frequency signal by regulating the supply of power to the transmission amplifier to amplify the outgoing radio-frequency signal.

2. The apparatus of claim 1 , wherein the apparatus is configured to switch the transmission power regulator from the off state to the on state when transmission of RFID sensor data is required, and is configured to switch the transmission power regulator from the on state to the off state when transmission of RFID sensor data is not required.

3. The apparatus of claim 1 , wherein the apparatus is configured to switch the transmission power regulator from the off state to the on state periodically, in response to a request for RFID sensor data and/or when the RFID sensor data reaches a predefined threshold value.

4. The apparatus of claim 1 , wherein the apparatus is configured to switch the transmission power regulator between the on and off states by providing signalling to the transmission power regulator to place the transmission power regulator in the on state or off state.

5. The apparatus of claim 1 , wherein the apparatus is configured to switch the transmission power regulator between the on and off states by respectively making and breaking an electrical connection between the power supply and transmission power regulator.

6. The apparatus of claim 5, wherein the apparatus is configured to operate a switch to make and break the electrical connection between the power supply and transmission power regulator.

7. The apparatus of claim 1 , wherein the apparatus comprises a processor and memory including computer program code, the memory and computer program code configured to, with the processor, switch the transmission power regulator between the on and off states.

8. The apparatus of claim 1 , wherein the apparatus comprises one or more logic gates configured to switch the transmission power regulator between the on and off states.

9. The apparatus of claim 1 , wherein the transmission power regulator is configured to regulate the supply of power from a power supply of the RFID sensor device to a reception amplifier of the RFID sensor device, and wherein the on state of the transmission power regulator allows for reception of data at the RFID sensor device as an incoming radio-frequency signal by regulating the supply of power to the reception amplifier to amplify the incoming radio-frequency signal.

10. The apparatus of claim 1 , wherein the off state of the transmission power regulator is a low power mode of the transmission power regulator.

11. The apparatus of claim 1 , wherein the transmission power regulator is configured to consume no more than 1 μ\Λ/ of power in the off state.

12. The apparatus of claim 1 , wherein regulating the supply of power from the power supply to the transmission amplifier comprises delivering up to 2W of power from the power supply to the transmission amplifier.

13. The apparatus of claim 1 , wherein the apparatus comprises one or more of the transmission power regulator and a sensor power regulator configured to regulate the supply of power from a power supply of the RFID sensor device to an RFID sensor of the RFID sensor device to enable generation of the RFID sensor data by the RFID sensor.

14. The apparatus of claim 13, wherein the transmission power regulator and sensor power regulator are configured to regulate the supply of power from a common power supply.

15. The apparatus of claim 13, wherein the sensor power regulator is configured to consume no more than 10pW of power in usage.

16. The apparatus of claim 1 , wherein the power supply has a power density of at least 100W/kg.

17. The apparatus of claim 1 , wherein the power supply comprises one or more supercapacitors.

18. The apparatus of claim 1 , wherein the apparatus is the RFID sensor device or a module for the RFID sensor device.

19. A method comprising switching a transmission power regulator of an RFID sensor device between on and off states, the transmission power regulator configured to regulate the supply of power from a power supply of the RFID sensor device to a transmission amplifier of the RFID sensor device, wherein the on state allows for transmission of RFID sensor data from the RFID sensor device as an outgoing radio- frequency signal by regulating the supply of power to the transmission amplifier to amplify the outgoing radio-frequency signal.

20. A computer program comprising computer code configured to control the method of claim 19.