Sensor system, mote and a motes-system for sensing an environmental parameter

Abstract

The invention provides a sensor system, mote and a motes-system. The sensor system is configured for being contained in a container having a maximum outer dimension less than 10 millimeter and for sensing at least one environmental parameter (T, P, pH, ). The sensor system includes at least one sensor configured for measuring the at least one environmental parameter and for generating a sensed value (xT, xP). The sensor system includes a storage element and a timer in which the at least one sensor is configured to measuring the at least one environmental parameter at each time triggers (t1, t2, . . . ) from the timer and for storing a sensed value (xT, xP). The sensor system further includes an energy storage comprising a chargeable capacitor being chargeable via electro-magnetic radiation of a predefined frequency, and wherein the sensor system is configured to initiate a sequence of sensed values when the energy storage is charged or is being charged.

Claims

1. A first sensor system configured for being contained in a container and for sensing at least one environmental parameter, the first sensor system comprising: at least one sensor configured for measuring the at least one environmental parameter and for generating a sensed value representing the at least one environmental parameter, a storage element for storing the sensed value, a first timer for generating a plurality of time triggers separated by a predetermined time interval, a first energy storage for supplying at least the at least one sensor, first timer and storage element with power to enable operation of the first sensor system during a predefined time duration, wherein the first energy storage comprises a chargeable capacitor being chargeable via electro-magnetic radiation of a predefined frequency, and an antenna for receiving the electro-magnetic radiation for charging the first energy storage, wherein: initialization of the first timer is based on a charge state of the first energy storage, the predetermined time interval separating the plurality of time triggers is configurable and independent from the charge state of the first energy storage, the at least one sensor is configured to generate a sequence of sensed values by measuring the at least one environmental parameter substantially at the time of each of the plurality of time triggers, generating a corresponding sensed value, and storing the sensed value onto the storage element, the electro-magnetic radiation can be simultaneously applied to a second energy storage of a second sensor system, the second energy storage being chargeable via the electro-magnetic radiation, the second sensor system having a second timer for generating a second plurality of time triggers separated by the predetermined time interval, such that: the first timer of the first sensor system is substantially synchronized with the second timer of the second sensor system, and the sequence of sensed values is substantially synchronized with a second sequence of sensed values from the second sensor system.

2. The first sensor system according to claim 1, wherein the initialization of the first timer comprises resetting the first timer.

3. The first sensor system according to claim 2, wherein the first timer comprises an oscillator and a counter and wherein the resetting of the first timer comprises resetting the counter.

4. The first sensor system according to claim 3, wherein the first sensor system is configured for storing a trigger number together with each sensed value, the trigger number being generated by the first timer and indicating a number of time triggers generated by the first timer since the resetting of the first timer.

5. The first sensor system according to claim 1, wherein the first sensor system further comprises a controller for controlling the operation of the first sensor system.

6. The first sensor system according to claim 5, wherein the controller is constituted of one or more logic blocks.

7. The first sensor system according to claim 5, wherein the controller is coupled to the antenna and is configured to communicate via the antenna.

8. The first sensor system according to claim 7, wherein the controller is configured for communicating the stored sensed values.

9. The first sensor system according to claim 7, wherein the controller is configured for receiving configurable parameters via the antenna for determining an operation of the first sensor system.

10. The first sensor system according to claim 7, wherein the predetermined time interval is a configurable parameter.

11. The first sensor system according to claim 1, wherein the at least one environmental parameter is selected from a list comprising at least temperature pressure, acidity, and conductivity.

12. The first sensor system according to claim 1, wherein the predefined time duration is at least 24 hours.

13. A first mote comprising the first sensor system according to claim 1 contained in the container, wherein the volumetric mass density of the first mote is substantially equal to the volumetric mass density of a predefined liquid.

14. A motes-system comprising the first mote according to claim 13, and a second mote comprising the second sensor system.

15. A method for collecting sensor data from an environment, the environment having an injection point, and an extraction point, the method comprising: applying the electro-magnetic radiation simultaneously to the first mote and the second mote according to claim 14, thereby substantially synchronizing the first timer of the first mote and the second timer of the second mote, injecting via an injection point the first mote and the second mote into the environment using a stream of liquid, allowing the first mote and the second mote to migrate through the environment via the injected liquid from the injection point to the extraction point, harvesting at least part of the first mote and the second mote from the environment via the extraction point, and extracting the stored sequence of sensed values from the harvested motes.

16. The method for collecting sensor data from an environment as in claim 15, comprising placing the harvested motes inside a tank containing liquid at a specific predefined temperature.

17. The method for collecting sensor data from an environment as in claim 15 wherein the environment is an oil well, water distribution system, sewer system, or a reservoir for a liquid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. In the drawings,

(2) FIG. 1 shows a remote environment, in which an environmental parameter is sensed using a plurality of motes according to the invention,

(3) FIG. 2A shows a first embodiment of a sensor system according to the invention, and FIG. 2B shows a second embodiment of the sensor system according to the invention,

(4) FIG. 3 shows a schematic view of a motes-system comprising a plurality of motes which can be charged and synchronized simultaneously,

(5) FIGS. 4A and 4B show possible containers for the sensor system according to the invention, and

(6) FIG. 5 shows possible data content of the storage element of a sensor system according to the invention.

(7) It should be noted that items which have the same reference numbers in different Figures, have the same structural features and the same functions, or are the same signals. Where the function and/or structure of such an item has been explained, there is no necessity for repeated explanation thereof in the detailed description.

DETAILED DESCRIPTION OF EMBODIMENTS

(8) FIG. 1 shows an environment 100 in which a mapping is required. The environment 100 shown in FIG. 1 represents an oil well 100 having a first cavity 110 which is connected to a second cavity 112 via a main passageway 120 and a plurality of smaller passageways 122. FIG. 1 further shows a plurality of motes 300 which are injected via an injection pipe 130 and which may be harvested via an extraction pipe 140. The motes 300 contain a sensor system 200A, 200B (see FIGS. 2A and 2B) which are contained in a spherical container (see FIG. 4A). Each of the motes 300 may, for example, be injected into the oil well 100 via the injection pipe 130 using a stream of hot water (not shown) which may, for example, be used to dilute some of the treacle cured oil to allow more of the treacle crude oil to be harvested. The stream of hot water typically has a temperature close to the boiling temperature of water. The motes 300 are designed to float or be buoyant in the injected liquid such that the motes 300 may migrate through the oil well via the injected liquid and such that some of the motes 300 may be harvested from the oil well 100 via the extraction pipe 140 together with the harvested crude oil or together with the extracted water. When the sensor system 200A, 200B inside the mote 300 is sensing the environmental temperature by creating a sequence of sensed temperature values x.sub.T (see FIG. 5), the variation in the sequence of the sensed temperature x.sub.T together with the overall time the motes 300 migrate through the well provide an indication about the extent of the oil well and whether the mote 300 migrated via the main passage way 120 from the injection pipe 130 to the extraction pipe 140 or via any of the smaller passageways 122.

(9) As indicated above, the motes 300 are preferably designed to float or be buoyant in the injected liquid. Floating or buoyancy is achieved when the volumetric mass density of a mote 300 substantially equals the volumetric mass density of the liquid. This ensures that the motes 300 preferably neither sink in the liquid nor rise; as a result the motes 300 will more easily enter all parts of the remote environment 100.

(10) In an alternative embodiment, the motes 300 which are injected into the remote environment are separated in different dimension groups (not shown), in which each mote 300 in a specific dimension group has predefined external dimension different from the motes from a different specific dimension group. As such, motes 300 having different dimensions are injected into the remote environment which now also enables to capture some information about the dimensions of the smaller passageways 122 that may be present inside the remote environment 100.

(11) Due to the overall small dimensions of the motes 300, the motes 300 may migrate relatively easily through the oil well 100 to provide information related to the extent of the oil well 100. Furthermore, using low energy consuming elements in the sensor system 200A, 200B enables the motes 300 according to the invention to migrate through the remote environment for more than 72 hours, which enables a mapping of relatively large remote environments 100.

(12) As indicated before, the remote environment 100 may, for example, be an underground reservoir 100, for example, used in mining or oil and gas industry. Alternatively, the remote environment 100 may be a sewer system 100 and/or (underground) water supply system 100 or subterranean river 100.

(13) FIG. 2A shows a first embodiment of a sensor system 200A according to the invention. The sensor system 200A comprises a sensor 210 for measuring or sensing an environmental parameter T, P, pH, and for generating the sensed value x.sub.T, x.sub.P (see FIG. 5) representing the value of the sensed environmental parameter T, P, pH, . The environmental parameter T, P, pH, may, for example, be the ambient temperature T surrounding the sensor system 200A or may, for example, be the ambient pressure P surrounding the sensor system 200A or an acidity pH of the surroundings of the sensor system 200A or the conductivity of the surroundings of the sensor system 200A. The sensor system 200A further comprises a storage element 220 for storing the sensed values x.sub.T, x.sub.P in a sequence of sensed values x.sub.T, x.sub.P. The storage element 220 may, for example, be a shift register 220 for storing the sequence of sensed values x.sub.T, x.sub.P. The benefit when using such a shift register 220 as storage element 220 is that they typically may be produced relatively small and consume relatively little energy. However, any other storage element 220 may be used which may be produced within the predefined dimensions of the sensor system 200A and which energy consumption is low enough to ensure the operation of the sensor system 200A for the predefined time duration. The sensor system 200A also comprises a timer 230 configured for generating a plurality of time triggers t1, t2 . . . separated by a predetermined time interval t. The sensor system 200A is configured that the sensor 210 measures the environmental parameter T, P, pH, when receiving a time trigger t1, t2, . . . from the timer 230 and stores the sensed values x.sub.T, x.sub.P sequentially in the storage element 220. Finally, the sensor system 200A comprises an energy storage 240 connected to an antenna 250. The energy storage 240 is configured for supplying the sensor 210, the storage element 220 and the timer 230 with energy during a predefined time durationwhich is indicated in FIG. 2A using the dash-dotted connection lines between the energy storage 240 and the sensor 210, storage element 220 and timer 230. The energy storage 240, for example, comprises a capacitor 240 which preferably is connected to an antenna 250 such that the energy storage 240 may be charged via electro-magnetic radiation (not shown) captured by the antenna 250. As such, the sensor system 200A may be charged wirelessly.

(14) The minimal design of the sensor system 200A as shown in FIG. 2A is capable of measuring the environmental parameter T, P, pH, as soon as the energy storage 240 is charged or is being charged. As soon as the energy storage 240 is charged or is being charged, the timer 230 generates time triggers t1, t2, . . . separated by predetermined time intervals t. Each time the sensor 210 receives a time trigger t1, t2, . . . the sensor 210 senses the current ambient environmental parameter T, P, pH, and generates a sensed value x.sub.T, x.sub.P. Each of these generated sensed values x.sub.T, x.sub.P are sequentially stored in the storage element 220 to generate a sequence of sensed values x.sub.T, x.sub.P. Knowing the time at which the energy storage 240 is charged or is being charged defines the start of the sequence of sensed values x.sub.T, x.sub.P and defines the exact time at which each of the sensed values x.sub.T, x.sub.P in the sequence of sensed values x.sub.T, x.sub.P are measured. Due to this architecture, relatively few on-board intelligence is necessary to allow the sensor system 200A according to the invention to gather and store the sequence of sensed values x.sub.T, x.sub.P, which enables a relatively small sensor system 200A which may operate during a significant predefined time duration in a remote environment.

(15) Thus the timer may not only start measurements and initiating sensing but also creates synchronizations between the motes in the system. As such the system/plurality of INCAS3 motes can perform coherently as a system. In an embodiment, motes reset only the timer upon charging without affecting the memory unit. As a result re-charging does not affect the stored memory values. Upon re-charging the timer generates a new sequence of triggers or trigger numbers; new sensed values could be stored with the new trigger numbers (time1, time2, . . . ) without overwriting previously stored sensed values and trigger numbers. In this embodiment, a mote may be re-charged before reading out. The read-out may be done using the antenna. In an embodiment, the readout can be done before recharging. The readout function may be independent or not coupled to the re-charging.

(16) When the energy storage 240 is exhausted, the sensor system 200A simply stops gathering the environmental parameter and awaits the time the sensor system 200A is harvested back from the remote environment. The data may be extracted from the storage element 220 in any known method, for example, by removing the sensor system 200A from the container and electronically connecting a data reader (not shown) to the storage element 220 for extracting the stored sequence of sensed values x.sub.T, x.sub.P. Using the sequence of sensed values x.sub.T, x.sub.P from a plurality of sensor systems 200A, information about the remote environment 100 may be gathered.

(17) The timer 230 shown in FIG. 2A may comprise an oscillator 232 and a counter 234. The oscillator 232 may be any oscillator 232 useable for generating a sequence of triggers t1, t2, . . . separated by the predefined time interval t in an electronic circuit, including, for example, a quartz oscillator. However, in view of the dimension and power restrictions a relatively low-power logic oscillator circuit 232 would be preferred. The counter 234 may be configured for generating a trigger number time1, time2, . . . for identifying individual triggers t1, t2, . . . generated by the oscillator 232. These trigger numbers time1, time2, . . . may be stored in the storage element 220 together with the sensed values x.sub.T, x.sub.P to uniquely identify the time at which each of the sensed values x.sub.T, x.sub.P in the sequence of sensed values x.sub.T, x.sub.P are measured.

(18) FIG. 2B shows a second embodiment of the sensor system 200B according to the invention. This second embodiment of the sensor system 200B also comprises a sensor 210 for sensing an environmental parameter T, P, pH, and for generating a sensed value xT, xP to be stored in the storage element 220. This second embodiment of the sensor system 200B further comprises the timer 230 for generating time triggers t1, t2, . . . and the energy storage 240 connected to the antenna 250 for wirelessly charging the energy storage 240 via electro-magnetic radiation. In addition, this second embodiment of the sensor system 200B further comprises a controller 260 for controlling the operation of the sensor system 200B. The controller 260 may, for example, be a state machine 260 which represents any device that stores a status or value of something at a given time. In a more advanced version of the controller 260, the controller 260 may be able to receive input, for example, via the antenna 250 (which is illustrated by the double arrow connecting the controller 260 and the antenna 250 in FIG. 2B). The state machine 260 may in some embodiments be preferred as controller 260 because such state machines 260 often comprise only a limited number of logic circuits 262, 264, often dedicated to the required controlling, such that a minimal amount of energy and space is required. Of course if energy and space limitations allow, also other types of controllers may be used in the sensor systems 200B according to the invention. The input received by the controller 260 may be used to, for example, change the status or way of working of the sensor system 200B dependent on the received input. The controller 260 used in the embodiment of the invention may, for example, ensure that the sensor 210 takes a sensed value x.sub.T, x.sub.P at each time trigger t1, t2, . . . generated by the timer 230 and that the sensed value x.sub.T, x.sub.P (possibly including the trigger number time1, time2, . . . ) is subsequently stored in the storage element 220. The storage element 220 may again, for example, be a shift register 220 in which the sensed values x.sub.T, x.sub.P are sequentially stored as they are measured by the sensor 210. The controller 260 may, for example, be constituted of one or more logic blocks 262, 264 as only very limited and basic control seems to be required for the operation of the sensor system 200B. Furthermore, constituting the controller 260 of a few logic blocks 262, 264 only would minimize the power required to run the sensor system 200B and would allow the sensor system 200B, including controller 260, to be contained in such small containers 400, 410. Of course, when power and dimension requirements are met to allow the sensor system 200B to operate during the predefined time duration, any controller system 260 or microcontroller 260 may be used as the controller 260 in the sensor system 200B.

(19) In an embodiment of the sensor system 200B as shown in FIG. 2B, the controller 260 is coupled to the antenna 250 via a double headed arrow. This double headed arrow indicates that there might be a two-way communication between the controller 260 and the antenna 250 such that the controller 260 is configured to communicate via the antenna. The controller 260 may, for example, be configured for communicating the stored sensed values xT, xP from the storage element 220 to the outsidefor example, a remote computer (not shown) used for the analysis of the data. When the sensor system 200B has been working in the remote environment 100 and has been harvested back from the remote environment 100, the controller 260 may be triggered, for example, using a release storage trigger signal (not shown) such that the sequence of sensed values xT, xP, possibly together with the corresponding trigger number t1, t2, . . . , is transmitted via the antenna 250. Alternatively or additionally, the controller 260 may be configured for receiving configurable parameters via the antenna 250 for configuring an operation of the sensor system 200B. The sensor system 200B may be configured using specific parameter settings which may, for example, be stored in the controller 260 or at a specific predefined place in the storage element 220. Such parameter settings may, for example, be the duration of the predetermined time interval t between two subsequent triggers t1, t2, . . . and/or the predefined time duration during which the sensor system 200B is to be operated.

(20) Using the antenna 250 both for charging the energy storage 220 and for communication of the controller 260 with the outside further reduces the overall elements required to allow the sensor system 200B to function, which further contributes to the miniaturization and cost reduction of the sensor system 200B according to the invention.

(21) In an embodiment, the mote can be configured or re-configured. The controller may be configured to receive over the antenna configurable parameters. The configurable parameters may define a basic functionality of mote. The basic functionality may include executing a different time sequence and/or selecting an environmental parameter for measurements. This is an advantageous feature of the motes-system because it allows having different groups of motes programmed with a different behavior, for example, one group of motes measures temperature and another group of motes measures pressure, or something else. When the two groups of motes are used (and charged) together coherent data is obtained given information over both aspects; in this example, temperature, and pressure. Having additional data, which is however synchronized reconstructing (e.g. mapping) an unknown environment is easier, e.g., requiring fewer computational resources.

(22) Of course different architectures of the second embodiment of the sensor system 200B are possible without diverting from the scope of the invention. For example, in the embodiment shown in FIG. 2B all communication inside the sensor system 200B is arranged via the controller 260 which is indicated with the double headed arrows going from the controller 260 to each of the other elements of the sensor system 200B. Of course, not all communication need to goes through the controller 260 as alternatively was shown in the first embodiment of the sensor system 200A (shown in FIG. 2A). Again, the power distribution in the sensor system 200B shown in FIG. 2B is illustrated by the connecting dash-dotted lines between the energy storage 240 and the remainder of the elements of the sensor system 200B.

(23) Sensor systems 200A, 200B as shown in FIGS. 2A and 2B may be contained in a container 400, 410 (see FIGS. 4A and 4B) to constitute a mote 300, 310. The material chosen for the container 400, 410 depends on the liquid through which the mote 300, 310 is designed to float and depends on the chemical composition of the liquid such that the sensor system 200A, 200B is protected from the environment it floats in while still being able to sense the environmental parameter T, P, pH, . As an alternative to the containers 400, 410 as shown in FIGS. 4A and 4B, the container may be constituted by melting a material such as plastic or a resin, and submerge the sensor system 200A, 200B in the molten material after which the molten material is hardened. Using such a container would encapsulate the sensor system 200A, 200B and fully protect the sensor system 200A, 200B from the surrounding environment. And because both the charging and initiation of the sensor system 200A, 200B is done wirelessly, such mote 300, 310 comprising an encapsulated sensor system 200A, 200B may be able to withstand very harsh environments.

(24) FIG. 3 shows a schematic view of a motes-system 500 comprising a plurality of motes 310 which can be charged and synchronized simultaneously. For charging a generator 600 may be in the vicinity of the plurality of motes 310 for emitting the electro-magnetic radiation. The motes 310 each comprise the sensor system 200A, 200B (see FIGS. 2A and 2B) according to the invention, comprising an antenna 250 configured for capturing part of the electro-magnetic radiation emitted by the generator 600 and using the captured part of the electro-magnetic radiation for charging energy storage 240 in each of the sensor systems 200A, 200B. In a preferred embodiment, the motes 310 are configured for starting the sequence of time triggers t1, t2, . . . and the sequence of sensed values x.sub.T, x.sub.P at the time the energy storage 240 is being charged or at the time the energy storage 240 is fully charged. In such a motes-system 500, each of the individual motes 310 are simultaneously charged and initiated via the generator 600 such that each of the sensor values x.sub.T, x.sub.P stored in corresponding positions in the storage element 220 of each of the individual motes 310 in the motes-system 50 is measured substantially at the same time.

(25) For mapping the remote environment 100, the motes-system 500 comprising a plurality of synchronized motes 310 are injected into the remote environment 100 and are configured to sense the environmental parameter T, P, pH, at substantially the same time triggers t1, t2, . . . generated by each individual timer 230 of each of the individual motes 310. When the plurality of motes 310 are subsequently harvested, the sequence of sensed values x.sub.T, x.sub.P may be analyzed to determine information about the remote environment 100. When including, next to the sequence of sensed values x.sub.T, x.sub.P, also the overall migration time necessary for the individual mote 310 to get from the injection point to the extraction point, relatively detailed information may be gathered from the data about the extent of the remote environment. More information about possible measurement principles may be found in the co-owned and co-pending patent application Method and system for mapping a three-dimensional structure using motes, with NL application number N2012483, which was filed at the same date at the Dutch patent office and which is incorporated herein by reference.

(26) FIGS. 4A and 4B show possible containers 400, 410 for the motes 300, 310 according to the invention. As indicated above, the motes 300, 310 according to the invention may be used in harsh environments 100 and so may require a specific container 400, 410 for protecting the motes 300, 310 while migrating through the harsh environment 100. Furthermore, the containers 400, 410 may protect the motes from mechanical impact of moving parts when they have to pass pumps used, for example, to harvest crude oil from the oil well 100. Finally, the containers 400, 410 may be used to ensure that the volumetric mass density of a mote 300, 310 substantially equals the volumetric mass density of the liquid. This ensures that the motes 300, 310 preferably neither sink in the liquid nor rise; as a result the motes 300, 310 will more easily enter all parts of the remote environment 100.

(27) The specific density of the mote controls their behavior according to the fluid dynamics. A suitable specific density or specific gravity may be achieved by choosing a suitable material for the container, e.g., casing, and their wall thickness and shape based on the design of a mote and volumetric calculations. In an embodiment, the container comprises ballast weight to control the density of the mote. In an embodiment, the density of the mote equals the density of water.

(28) The maximum outer dimensions D of the container 400 shown in FIG. 4A is a diameter indicated with the double-headed and should be less than 10 millimeter. The maximum outer dimension L of the container 410 shown in FIG. 4B is a length parameter measured along the longitudinal axis of the elongated container 410 which should be less than 10 millimeter.

(29) The motes may be used in a method for collecting sensor data from an environment, the environment having an injection point (130), and an extraction point (140). The method may comprise charging a plurality of motes via electro-magnetic radiation, thereby initiating in the plurality of motes, measuring of at least one environmental parameter (T, P, pH, ) substantially at the time of each of a plurality of time triggers (t1, t2, . . . ) and for generating a corresponding sensed value (x.sub.T, x.sub.P) and storing the sensed value (x.sub.T, x.sub.P) onto the storage element (220), generating a sequence of sensed values (x.sub.T, x.sub.P), the plurality of time triggers being separated by a predetermined time interval (t) injecting via an injection point (130) the plurality of motes into the environment (100) using a stream of liquid, allowing the plurality of motes (300) to migrate through the environment via the injected liquid from the injection point (130) to the extraction point (140), harvesting at least part of the plurality of motes (300) from the environment (100) via the extraction point (140) extracting the stored sequences of sensed values (x.sub.T, x.sub.P) from the harvested motes.

(30) In an embodiment, the method may further comprise placing harvested motes inside a tank containing liquid at a specific predefined temperature. In this way the time at which the mote is harvested is registered.

(31) The environment may be any environment in which motes may be inserted and extracted using a liquid. For example the environment may be an oil well, the injection point is an injection pipe, and the extraction point is an extraction pipe. The environment can be, for example, a sewer system, a water distributing network, an oil reservoir, etc. The inserting and extraction point can be, for example, an inserting port or pipe or well, etc.

(32) FIG. 5 shows possible data content of the storage element 220 of a sensor system 200A, 200B according to the invention. The storage element 220 may be a relatively simple shift register 220 for sequentially storing the stored values x.sub.T, x.sub.P, possible together with the trigger number time1, time2, . . . . As indicated before, any other type of storage element 220 apart from a shift register 220 may be used, as long as the dimensions of the storage element 220 and the energy consumption of the storage element 220 allow the operation of the mote 300, 310 during the predefined time duration.

(33) In FIG. 5, the left-hand column comprises a tabled listing of trigger values time1, time2, . . . is shown as a relatively simple sequence of numbers. Each of the trigger values time1, time2, . . . which is listed in the table are generated separated by the predetermined time interval t. As indicated before, this predetermined time interval t may be configurable and may, for example, ensure that the environmental parameter is measured every 5 minutes, or every 10 minutes, or every 15 minutes, or every half hour, or every hour.

(34) In FIG. 5, the right-hand column comprises the sensed values x.sub.T, x.sub.P which are temperature values x.sub.T which represent the ambient temperature at the immediate vicinity of the sensor system 200A, 200B at the corresponding time values time1, time2, . . . . In the current example, the temperature value x.sub.T is indicated in Kelvin. The sequence shown, for example, represents a pre-conditioned state in which the motes 300, 310 are kept in a tank containing ice-water at 0 degrees Celsius (approximately 273 degrees Kelvin). Next, the motes 300, 310 are inserted into boiling water which is injected into the remote environment 100 which can be seen from the stored data in that the temperature of the mote 300, 310 immediately rises to 100 degrees Celsius (or approximately 373 degrees Kelvin). Next, the cooling of the mote 300, 310 is shown in the subsequent sensed values x.sub.T in the listing of FIG. 5. This cooling sequence depends on the exact path taken through the remote environment 100 by the individual motes 300, 310. By collecting a plurality motes 300, 310 and by analyzing the different cooling sequences of the individual motes 300, 310 an extent of the remote environment may be determined.

(35) Although the data content shown in FIG. 5 includes both the trigger number time1, time2, . . . and the sensed value x.sub.T, x.sub.P, the trigger number time1, time2, . . . is optional as the actual time the measurements are taken may already be defined by the position in the sequence of sensed values x.sub.T, x.sub.P as stored in the storage element 220.

(36) Summarizing, the invention provides a sensor system 200), mote and a motes-system. The sensor system is configured for being contained in a container having a maximum outer dimension less than 10 millimeter and for sensing at least one environmental parameter T, P, pH, . The sensor system comprises at least one sensor 210 configured for measuring the at least one environmental parameter and for generating a sensed value x.sub.T, x.sub.P. The sensor system comprises a storage element 220 and a timer 230 in which the at least one sensor is configured to measuring the at least one environmental parameter at each time triggers t1, t2, . . . from the timer and for storing a sensed value x.sub.T, x.sub.P. The sensor system further comprises an energy storage 240 comprising a chargeable capacitor 240 being chargeable via electro-magnetic radiation of a predefined frequency, and wherein the sensor system is configured to initiate a sequence of sensed values when the energy storage is charged or is being charged.

(37) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments.

(38) In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb comprise and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article a or an preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.