Temperature indicator

Abstract

The temperature indicator includes a microsensor having a sensing element with a first layer coupled to a second layer, the first and second layers having different coefficients of expansion. The sensing element is configured to move from a first position to a second position upon exposure to a temperature event, and includes a detection circuit configured to change from a first state to a second state when the sensing element moves to the second position. The detection circuit is prevented from returning to the first state upon changing to the second state. An RFID module is coupled to the detection circuit and configured to output a value indicating that the sensing element is in the second position. An activation element is configured to maintain the sensing element in the first position until the activation element is removed from the microsensor.

Description

Summary of the Invention [Problem to be solved by the invention]

[0001] Many types of objects need to be monitored or tracked during manufacture, storage, or transportation due to the temperature sensitivity or fragility of the objects. For example, some types of objects may be spoiled when exposed to certain temperatures (e.g., food or pharmaceuticals). Therefore, it is desirable to determine and / or verify the environmental conditions to which the objects have been exposed for quality control and / or general monitoring of transportation conditions. [Means for solving the problem]

[0002] According to one aspect of the present disclosure, devices and techniques for temperature detection are disclosed. The temperature indicator includes a microsensor having a sensing element with a first layer coupled to a second layer, the first layer and the second layer having different coefficients of expansion. The sensing element is configured to move from a first position to a second position upon exposure to a temperature event. The microsensor further includes a detection circuit configured to change from a first state to a second state when the sensing element moves from the first position to the second position. Once the detection circuit changes to the second state, the detection circuit is prevented from returning to the first state. The temperature indicator also includes a radio frequency identification (RFID) module coupled to the detection circuit, the RFID module configured to output a value indicating that the sensing element is in the second position. The temperature indicator also includes an activation element configured to maintain the sensing element in the first position until the activation element is removed from the microsensor.

[0003] According to another embodiment of the present disclosure, a temperature indicator includes a substrate having a communication module inlay configured to communicate an operating state of the temperature indicator, a microsensor communicatively coupled to the communication module inlay for detecting a temperature event, the microsensor having a non-reversible detection circuit configured to detect the operating state, and an activation element configured to maintain the microsensor in a non-responsive state until disconnected from the microsensor.

[0004] According to yet another embodiment of the present disclosure, a temperature indicator includes a microsensor configured to activate upon receiving a temperature event. The microsensor has a detection circuit configured to change from a first state to a second state in response to activation of the microsensor, and the detection circuit is prevented from returning to the first state in response to activation. The temperature indicator also includes a radio frequency identification (RFID) module coupled to the detection circuit, the RFID module configured to output a value indicative of activation of the microsensor. The temperature indicator also includes an activation element configured to maintain the microsensor in a non-responsive state until disconnected from the microsensor. [Brief explanation of the drawings]

[0005] For a more complete understanding of the present application, its objects and advantages, reference is made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0006] [Figure 1] 1A-1C illustrate applications of embodiments of temperature indicators according to the present disclosure. [Figure 2] 1 is a block diagram illustrating an embodiment of a temperature indicator according to the present disclosure. [Figure 3] 1 is an exploded view of an embodiment of a temperature indicator according to the present disclosure. [Figure 4] FIG. 4 is an enlarged view of a portion of the temperature indicator shown in FIG. 3 according to the present disclosure. [Figure 5]5A and 5B illustrate an embodiment of a microsensor of the temperature indicator of FIGS. 3 and 4 in accordance with the present disclosure. [Figure 6] 6 illustrates the temperature indicator embodiment of FIG. 5 in an activated state in accordance with the present disclosure. [Figure 7] FIG. 7 is an enlarged view of a portion of the temperature indicator shown in FIGS. 5 and 6 according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0007] Embodiments of the present disclosure provide devices and techniques for detecting and indicating temperature. According to one embodiment, a temperature indicator includes a microsensor having a sensing element with a first layer coupled to a second layer, the first and second layers having different coefficients of expansion. The sensing element is configured to move from a first position to a second position upon exposure to a temperature event. The microsensor further includes a detection circuit configured to change from a first state to a second state when the sensing element moves from the first position to the second position. Once the detection circuit changes to the second state, the detection circuit is prevented from returning to the first state. The temperature indicator also includes a radio frequency identification (RFID) module coupled to the detection circuit, the RFID module configured to output a value indicative of the sensing element being in the second position. The temperature indicator also includes an activation element configured to maintain the sensing element in the first position until the activation element is removed from the microsensor. Embodiments of the present disclosure enable temperature event detection without the use of an internal power source. The RFID module can detect the state of a switch circuit and emit or output a value indicative of the activation state of the temperature indicator. For example, in some embodiments, an RFID reader may be used to activate the RFID module and determine the operational state of the temperature indicator. Additionally, embodiments of the present invention may use a microsensor (e.g., a micromechanical and / or microelectronic component) to detect a temperature event, the microsensor having circuitry that provides irreversibility of the operational state of the temperature indicator after detecting a temperature event. Additionally, embodiments of the present invention may provide for in situ activation of the temperature indicator (i.e., maintaining the temperature indicator in a non-responsive state) such that a temperature event detected prior to the intended application of the temperature indicator does not unintentionally activate the temperature indicator.

[0008] Many types of objects require monitoring of their temperature (i.e., cold chain) during storage, transportation, or use. For example, some types of objects, such as food or medicine, may become perishable or ineffective if exposed to too high a temperature for too long. The duration or threshold of a temperature excursion (i.e., a "time-temperature" variable) is often more important than a non-duration, i.e., real-time, temperature measurement. Therefore, it is desirable to determine and / or verify the temperature conditions to which an object has been exposed for quality control and / or general monitoring of transportation conditions.

[0009] Referring to the drawings, and in particular to FIG. 1 , an exemplary diagram of a temperature indicator 10 is shown in which the illustrated embodiments of the present disclosure may be implemented. FIG. 1 is a front view of the temperature indicator 10. In FIG. 1 , the temperature indicator 10 is a portable device configured to be attached to or placed within a shipping container containing an object for which an associated temperature event is to be monitored. Embodiments of the temperature indicator 10 monitor whether the object has been exposed to a particular temperature or environment during the manufacture, storage, and / or transportation of the object. In certain embodiments, the temperature indicator 10 may be attached to the shipping container using, for example, adhesives, permanent or temporary fasteners, or various different types of attachment devices. The shipping container may include a container in which the monitored object is loosely placed, or may include the container of the monitored object itself. It should be appreciated that FIG. 1 is merely exemplary and is not intended to assert or imply any limitation with regard to the environment in which various embodiments may be implemented.

[0010] In the embodiment shown in FIG. 1 , temperature indicator 10 includes a housing 12 within which a temperature-sensing, temperature-sensitive, and / or temperature-detecting assembly 14 is disposed. In the illustrated embodiment, temperature-detecting assembly 14 is configured to detect and indicate a temperature event associated with temperature indicator 10 (e.g., to detect when temperature indicator 10 (and correspondingly, the container with which temperature indicator 10 is associated) is exposed to a particular environmental temperature). In some embodiments, housing 12 is constructed and / or composed of a transparent or translucent material, and a masking label 16 is provided on or affixed to the front surface of the housing. In some embodiments, masking label 16 is configured with one or more openings or “windows” 18 to provide a visual indication of temperature detection. For example, in some embodiments, when temperature indicator 10 is exposed to a particular temperature, a visual indication is displayed by temperature-detecting assembly 14 within or through one or more windows 18 to visually indicate that the monitored object is or may be exposed to a certain level of temperature. However, it should be understood that other methods may be used to provide a visual indication that the temperature detection assembly 14 has been activated and / or otherwise placed in an activated state to indicate that the indicator 10 has been exposed to a certain level of temperature. Additionally, it should be understood that the housing 12 may be constructed and / or manufactured from other materials (e.g., an opaque material having one or more windows 18 formed therein). In some embodiments, the housing 12 may be constructed without a window 18. For example, as described in more detail below, the temperature indicator 10 may be configured to provide a visual and / or non-visual indication (e.g., using an RFID signal) of whether a temperature condition has been imposed on the temperature indicator 10.

[0011] 2 is a block diagram representing and illustrating an embodiment of an indicator 10 according to an embodiment of the present disclosure. In FIG. 2, indicator 10 includes a microsensor 20 and a wireless communication module 22. Microsensor 20 is a micromechanical and / or microelectronic device (e.g., a miniature device or system (e.g., typically having micrometer-sized components with an overall size typically measured in square millimeters)) for detecting a temperature event (e.g., a temperature above a certain threshold). The microsensor 20 may be configured as a microelectromechanical systems (MEMS) device (e.g., using silicon or other materials in a process or technique where layers of material are deposited and photolithographically patterned and etched to produce the required shapes / components), as a liquid crystal display (LCD) panel fabricated device (e.g., a device fabricated using LCD manufacturing processes, e.g., patterning, laminating, masking, cutting, and thin film transistor (TFT) deposition techniques, using glass components and / or glass substrates that may or may not contain liquid crystals), and / or may be formed using roll-to-roll (R2R) processing techniques (e.g., fabricating the device on a roll of soft plastic, metal foil, or flexible glass). In one embodiment, the temperature indicator 10 may be affixed (permanently or removably) to a printed circuit board and / or otherwise connected, permanently or removably, to an electronic circuit (e.g., a removable cartridge) such that, upon receipt and / or detection of a temperature condition of sufficient magnitude and / or exceeding one or more particular thresholds, the temperature indicator 10 provides an electronic signal / indication of such event.

[0012] In one embodiment, the microsensor 20 includes a detection circuit 24. The detection circuit 24 may include one or more switch elements, traces, contacts, and / or circuitry that responds to detecting a change in the operational state of the sensor 20. For example, in one embodiment, the sensor 20 may include a movable element or member that moves or displaces in response to a temperature event. Displacement of the movable element may change the state of the detection circuit 24 (e.g., change impedance, change from an open circuit state to a closed circuit state, or vice versa). The wireless communication module 22 is configured to wirelessly communicate information related to the state of the detection circuit 24, which indicates the operational state of the indicator 10 (e.g., based on the open or closed circuit state of the detection circuit 24). For example, in one embodiment, the wireless communication module 22 includes an RFID module 30. In one embodiment, the RFID module 30 includes a passive RFID module 30 (e.g., a passive RFID tag) having an RFID integrated circuit or circuit 32 (e.g., disposed on or as part of a printed circuit board) and a memory 34 along with an antenna 36. As a passive RFID module 30, indicator 10 does not include a battery (e.g., it is powered by RFID reader 40), thereby forming a battery-less temperature indicator 10. For example, when RFID module 30 receives radio waves from RFID reader 40, antenna 36 generates a magnetic field, thereby providing power to RFID module 30 and energizing RFID circuitry 32. When powered / activated, RFID module 30 may output / transmit information encoded in memory 34 (e.g., using a communication protocol such as NFC, ISO-18000-3, ISO 18000-6, UHF Gen2, ISO-15693, etc.). However, it should be understood that in some embodiments, RFID module 30 may have an active RFID module 30 that includes a power source (e.g., a battery) that may be configured to transmit or transmit information continuously, intermittently, and / or in response to a program or event trigger. One embodiment of a passive RFID tag is a rolled flex circuit RFID.In flex circuit RFID, the chip and antenna are embedded in a 100-200 nm thin substrate, such as polyvinyl chloride (PVC), polyethylene terephthalate (PET), phenolic, polyester, styrene, or paper, by copper etching or hot stamping. One process for RFID manufacturing is screen printing using conductive inks containing copper, nickel, or carbon. An example of a commercially available flex circuit passive RFID tag product, which can come in hundreds or thousands per roll, is Avery Dennison Corporation's Smartrac™ product.

[0013] It should be further understood that wireless communication module 22 may be configured for other types of wireless communication types, modes, protocols, and / or formats (e.g., Short Message Service (SMS), wireless data using General Packet Radio Service (GPRS) / 3G / 4G, wireless data over the public Internet via Wi-Fi, or wireless data locally using other wireless communication protocol standards such as Wi-Fi, Z-Wave, ZigBee, Bluetooth®, Bluetooth Low Energy (BLE), LoRA, NB-IoT, SigFox, Digital Enhanced Cordless Telecommunications (DECT), or other common technologies). As described further below, temperature indicator 10 functions as a passive temperature sensor / indicator that may be used as part of an electronic signal or circuit upon receiving a temperature event of a particular level and / or magnitude. In certain embodiments, the temperature sensing capabilities / functions of temperature indicator 10 of the present disclosure do not require power during a monitoring state.

[0014] In the illustrated embodiment, memory 34 includes at least two different stored and / or encoded values ​​42 and 44. For example, value 42 may correspond to a value output / transmitted by RFID module 30 when detection circuit 24 is in an open-circuit state or condition, and value 44 may correspond to a value output / transmitted by RFID module 30 when detection circuit 24 is in a closed-circuit state or condition. As an example, value 44 may represent an RFID tag identification (ID) number when temperature detection circuit 24 is not activated, where the RFID tag's ID number may have an additional character (e.g., a "0") at the end. Value 42 may represent an RFID tag identification (ID) number when temperature detection circuit 24 is activated, where the RFID tag's ID number may have an additional character (e.g., a "1") at the end that is different from the additional character of value 44. In the illustrated embodiment, RFID module 30 (e.g., RFID circuit 32) is coupled to detection circuit 24 and is capable of detecting whether detection circuit 24 is in an open-circuit or closed-circuit state or condition. Thus, for example, detection circuit 24 may initially be in a closed-circuit state or condition. Therefore, when RFID module 30 is energized / activated, it transmits value 44 to reader 40. When indicator 10 is exposed to a temperature event, sensor 20 causes a change in detection circuit 24, causing detection circuit 24 to assume an open-circuit state or condition. Therefore, when energized / activated (e.g., after a temperature event), RFID module 30 instead transmits value 42 to reader 40. Thus, embodiments of the present invention enable indicator 10 to use an electronic indicator (e.g., an RFID reader) to monitor a sensitive product / object to which it is attached for damage that may be caused by temperature changes, even though indicator 10 does not include or require any internal power source (e.g., a battery). In some embodiments, detection circuit 24 is configured to be irreversible, such that a change in state of detection circuit 24 prevents detection circuit 24 from reverting to its previous state.For example, if detection circuit 24 is in a closed-circuit state or condition prior to activation of sensor 20, and a temperature event activates sensor 20 and transitions detection circuit 24 to an open-circuit state or condition, detection circuit 24 cannot return to a closed-circuit state because it is configured to remain in the open-circuit state. Similarly, detection circuit 24 may be configured to transition from an open-circuit state to a closed-circuit state in response to activation of sensor 20, and then remain in the closed-circuit state without transitioning back to an open-circuit state. Thus, embodiments of the present invention prevent any unauthorized resetting of temperature indicator 10. Indicator 10 may be configured to have more or fewer values ​​stored in memory 34 (e.g., one value that is emitted only when sensor 20 is activated, different values ​​that are emitted in response to different temperature thresholds being exceeded, etc.).

[0015] The present invention may include computer program instructions at any technically feasible level of detailed integration (e.g., stored in one or more computer-readable storage media (e.g., memory 34)) for causing a processor to perform aspects of the present invention. The computer-readable program instructions described herein may be downloaded to a respective computing / processing device (e.g., wireless communication module 22 and / or RFID module 30). The computer-readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, configuration data for an integrated circuit, or source code or object code written in any combination of one or more programming languages. In some embodiments, an electronic circuit (e.g., circuit 32), including, for example, a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may execute the computer-readable program instructions using state information from the computer-readable program instructions to customize the electronic circuit to implement aspects of the present invention. Aspects of the present invention are described herein with reference to illustrations and / or block diagrams of methods and / or apparatus according to embodiments of the present invention. It will be understood that each block of the illustrations and / or block diagrams, and combinations of blocks in the illustrations and / or block diagrams, may represent modules, segments, or portions of code that can be implemented by computer-readable program instructions. These computer-readable program instructions may be provided to a processor or other programmable data processing device to produce a machine, such that the computer-readable program instructions, executed via the processor, provide means for performing the functions / operations specified in one or more blocks of the illustrations and / or block diagrams.These computer-readable program instructions, which may direct a computing device, programmable data processing apparatus, and / or other device to function in a particular manner, may further be stored on a computer-readable storage medium, such that the computer-readable storage medium having the instructions stored thereon comprises an article of manufacture including instructions that perform aspects of the functions / operations specified in one or more blocks of the illustrations and / or block diagrams. The detection circuit 24, the wireless communication module 22, and / or the RFID module 30 may be implemented in any suitable manner using known technology, which may be hardware-based, software-based, or some combination of both. For example, the detection circuit 24, the wireless communication module 22, and / or the RFID module 30 may include software, logic, and / or executable code (e.g., as software and / or algorithms executing on a processor unit, residing on a processor or other type of logic chip, or as hardware logic aggregated on a single integrated circuit or distributed across different chips in a data processing system) for performing various functions as described above. As will be appreciated by those skilled in the art, aspects of the present disclosure may be embodied as a system, method, or computer program product. Accordingly, aspects of the present disclosure may take the form of a hardware embodiment, a software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, which may all be generally referred to herein as a "circuit," "module," or "system."

[0016] FIG. 3 is an exploded view illustrating various embodiments of a temperature indicator 10 according to the present disclosure, and FIG. 4 is an enlarged view of a portion of the embodiment of the temperature indicator 10 shown in FIG. 3 according to the present disclosure. Referring to FIG. 3, the temperature indicator 10 includes an enclosure or housing 50 having a bottom or lower wall 52 and a top or upper wall 54. An RFID module 30 is disposed between the top wall 54 and the bottom wall 52. FIG. 4 is an enlarged view of the RFID module 30. In FIGS. 3 and 4, the RFID module 30 includes a substrate 60 having an RFID inlay 62 forming an antenna 36, ​​with an RFID chip or RFID circuit 32 coupled to the RFID inlay. In the illustrated embodiment, a microsensor 20 is bonded and / or coupled to the RFID module 30. For example, in the illustrated embodiment, the sensor 20 may include a MEMS sensor 201, a sensor 202 fabricated from an LCD panel, or a microsensor 203 fabricated from a R2R. Referring to FIG. 4, RFID module 30 has a mounting area 66 for receiving microsensor 20, and RFID module 30 further has traces or leads 68 for communicatively and / or electrically coupling sensor 20 to RFID circuitry 32.

[0017] Referring to FIG. 3 , in the illustrated embodiment, indicator 10 includes an activation element 70. Activation element 70 is configured to maintain sensor 20 in an inactive state (i.e., unable to transition from an inactive state to an activated state) until activation element 70 is removed from indicator 10, where inactive state refers to the state of sensor 20 before sensor 20 experiences a temperature event above a certain threshold, and activated state refers to the state of sensor 20 after sensor 20 experiences a temperature event at or above that threshold. For example, while indicator 10 is being transported to an end user (or otherwise), indicator 10 may experience a temperature event that is detected by sensor 20 and causes sensor 20 to enter an activated state (i.e., indicate that a temperature event has been experienced). Activation element 70 prevents sensor 20 from transitioning from an inactive state to an activated state, even if sensor 20 experiences a temperature event. When activation element 70 is removed from indicator 10, sensor 20 enters an active or sensing mode (i.e., can detect a temperature event and transition to an activated state to indicate that a temperature event has been experienced).

[0018] For example, as described in more detail below, in one embodiment, activation element 70 includes a retaining element 72 adhesively bonded and / or otherwise coupled to top wall 54 and includes a blocker 74 extending downwardly through an opening 80 formed in top wall 54. Blocker 74 may be in the form of a pin or other structural member that extends downwardly and engages at least a portion of sensor 20 to prevent activation of sensor 20. In operation, removing retaining element 72 from indicator 10 (e.g., peeling retaining element 72 from top wall 54) further pulls blocker 74 outwardly from indicator 10, thereby disengaging blocker 74 from sensor 20 and allowing sensor 20 to activate when sensor 20 detects a temperature event.

[0019] Figure 5 illustrates an embodiment of a temperature indicator 10 incorporating a MEMS-based microsensor 20 according to the present disclosure in an unactivated, unresponsive state, and Figure 6 illustrates an embodiment of the temperature indicator 10 of Figure 5 in an activated state according to the present disclosure. Sensor 20 represents at least one of what may be any number of sensors 20 in indicator 10 (more than one sensor 20 may be required if calibration of sensor 20 is required).

[0020] In the illustrated embodiment, the sensor 20 includes a sensing element 100 configured to move (e.g., from a first position or location, such as shown in FIG. 5, to a second position or location, such as shown in FIG. 6) upon exposure to a temperature event. The sensing element 100 may include multiple material layers, at least two of which have different temperature sensitivities. For example, in the illustrated embodiment, the sensing element 100 includes a cantilever structure 102 having multiple layers or beams 104 and 106. The beams 104 and 106 are formed such that one of the beams 104 and 106 includes at least one material that is different from the other beam 106 or at least one material in the beam 104. In the illustrated embodiment, beams 104 and 106 are arranged parallel (or substantially parallel) alongside or next to each other, and spaced apart by at least a distance, to define a gap 108 between beams 104 and 106 along the length of beams 104 and 106. In this embodiment, cantilever 102 is formed as a planar structure. Cantilever 102 may be disposed in a different plane than the structure underlying sensor 20 (e.g., substrate 60 (FIG. 3)). While cantilever structure 102 is shown as having a beam in the illustrated embodiment, it should be understood that sensor 20 may have other cantilever or non-cantilever structures, including flat structures such as diaphragms. The term "bimorph" is generally used to refer to the bending action in a beam formed by two active layers, and this term is used more generally to refer to the bending action that a combination of different materials can cause in a cantilever structure when exposed to a parameter of interest. In particular, the different materials are selected to have inconsistent expansion / contraction (stretching / shrinking) responses to the parameters of interest, so that the cantilever structure bends towards a beam that either compresses more or does not stretch as much as the other beam.When the parameter is at a sufficiently high (threshold) level, deflection of the cantilever structure may be sufficient to open or close (depending on the operational mode of the sensing device) an electrical contact associated with the cantilever structure, which may serve to interrupt or allow, respectively, the movement of charge or current, the generation of a voltage, or to provide another form of output that may correspond to a digital signal. Contact between the cantilever structure and the electrical contact is referred to herein as contact-mode switching function or contact-mode operation, and in some embodiments as unlocked (i.e., the cantilever structure is not mechanically locked or otherwise secured to the electrical contact other than as a result of bending or deflection).

[0021] In a preferred embodiment, the change in the property of the sensing element 100 in response to a parameter is temporary and reversible. For example, when the sensing element 100 responds to temperature (thermal expansion or contraction), the resulting reaction (deflection) of the cantilever structure 102 is temporary, and the cantilever 102 will return to its original configuration once the temperature excursion ends, unless the cantilever is mechanically restrained from returning to its original configuration (e.g., by locking the bent cantilever or otherwise restricting the movement of the cantilever 102 back to its original position / shape).

[0022] In the illustrated embodiment, the sensor 20 includes a support member 110 that is fixed to (or integrally formed as part of) the cantilever 102. In some embodiments, the support member 110 is fabricated as a feature on a conventional CMOS circuit board on which the sensor 20 may also be fabricated. As shown in FIGS. 5 and 6 , an end 120 of the cantilever 102 proximate the support member 110 is coupled to or formed as part of the support member 110, while an opposite, distal end 122 of the cantilever 102 is floating and / or free-standing relative to any adjacent substrate or structure, allowing the end 122 to move relative to the fixed end 120. In the illustrated embodiment, the end 122 is located proximate a latch or locking tab 130. For example, the latch 130 has an end 132 that is coupled to or formed as part of a support member 134. When cantilever 102 is in an unactuated or unresponsive state (FIG. 5), opposite distal end 136 of latch 130 is floating and / or free-standing and positioned adjacent to, but not in contact with, end 122 of cantilever 102. In the illustrated embodiment, face 140 of end 136 faces face 142 of end 122 of cantilever 102. Faces 140 and 142 are configured parallel to one another in the unactuated or unresponsive state (FIG. 5) and are spaced apart from one another. Surface 140 and surface 142 are angled such that at least a portion of surface 140 extends across at least a portion of surface 142 (e.g., surface 142 is formed at an acute angle relative to surface 144 of beam 106, and surface 140 is formed at a supplemental angle relative to surface 144 toward cantilever 102). Latch 130 is configured as a flexible latch 130 such that as cantilever 102 moves in the direction indicated by arrow 150, surface 142 contacts surface 140 and latch 130 moves away from cantilever 102 in the direction indicated by arrow 152, allowing cantilever 102 to pass end 136 of latch 130 in response to a thermal event.

[0023] As shown in FIG. 5 , the sensor 20 includes an activation element 70 such that during manufacturing, storage, and / or shipping of the indicator 10 (e.g., before the indicator 10 is placed on an item being temperature monitored), the cantilever 102 does not move a sufficient distance in direction 150 to engage with the latch 130 when the sensor 20 is exposed to a temperature event. As shown in FIG. 5 , the activation element 70 includes a block 74 disposed proximate to the cantilever 102, thereby limiting movement of the cantilever 102 in direction 150 when the sensor 20 experiences a temperature event. It should be understood that the block 74 may be otherwise disposed and / or positioned proximate to the cantilever 102 to limit and / or prevent movement of the cantilever 102 to a point where the sensor 20 is in an activated position or state.

[0024] The sensor 20 and its cantilever structure 102 may be fabricated directly on an integrated circuit substrate (e.g., a CMOS wafer) on which other electronic devices of the indicator 10 (e.g., RFID circuit 32, antenna 36, ​​etc.) may also be formed. Alternatively, the sensor 20 and its cantilever structure 102 are fabricated on a separate substrate that is then electrically coupled or bonded to a different substrate. It can be readily appreciated that the cantilever structure 102 of the sensor 20 is compatible with post-CMOS processing and can be fabricated in a very small area, even when the sensor 20 has multiple cantilevers 102. It should further be understood that structures other than cantilevers can be employed that can respond to environmental parameters of interest by closing and / or opening electrical contacts.

[0025] In the illustrated embodiment, the different materials of beam 104 and beam 106 are selected to cause cantilever structure 102 to bend or flex in direction 150 ( FIG. 5 ) in response to the environmental parameter of interest (e.g., beam 104 and beam 106 each comprise materials having different temperature-related expansion coefficients). As shown in FIGS. 5 and 6 , distal end 122 of beam 106 fills gap 108 to connect to distal end 160 of beam 104. As noted above, the individual response of cantilever structure 102 to the environmental parameter of interest may be referred to as bimorph in the following description, although it should be understood that a strictly bimorph cantilever structure 102 is not required (e.g., cantilever structure 102 does not necessarily require two active beams 104, 106; instead, cantilever structure 102 may have one active beam or three or more active beams). The sensor 20 may be configured to sense many different types of environmental parameters (e.g., temperature, moisture / humidity, electromagnetic radiation, nuclear particle radiation, chemicals, biological materials, etc.) to which the RFID module or RFID tag 30 may be subjected. Such functionality may be achieved by using appropriate materials to form the cantilever structure 102 of the sensing element 100, as will be understood from the following description.

[0026] As previously described, the different materials of beam 104 and beam 106 are selected to have mismatched expansion / contraction (stretching / shrinking) responses to parameters of interest such that under certain environmental conditions (e.g., threshold temperatures or time-temperature parameters), beam 106 expands more or contracts less than beam 104, causing cantilever structure 102 to bend in direction 150. Because beams 104 and 106 are arranged side-by-side and attached at their distal ends 160, 122, cantilever structure 102 deflects in a direction in the plane of cantilever structure 102 and its beams 104 and 106. Because beams 104 and 106 are arranged side by side and parallel, a gap 108 is defined between beams 104 and 106 and is shown to be uniform in width along the length of beams 104 and 106. Because of gap 108, beams 104 and 106 do not directly contact each other along most of their lengths; only distal end 122 of beam 106 fills gap 108 and is attached to distal end 160 of beam 104. Thus, the active lengths of beams 104 and 106 that create the bimorph action do not directly contact or interact with each other.

[0027] According to some embodiments of the present disclosure, the sensor 20 is a MEMS device (i.e., has a detection circuit 24) that functions as a switch in response to one or more environmental parameters of the environment surrounding the indicator 10. For example, in some embodiments, the detection circuit 24 may be formed as part of (or directly on) the cantilever 102. For example, in some embodiments, the beam 106 (and its distal end 122) and the locking pawl 130 are conductive so that they function as a switch when they contact each other. In this embodiment, the support members 110, 134 are also at least partially conductive to serve as contacts for the detection circuit 24. In some embodiments, the cantilever 102 and / or the locking pawl 130 may have an outer layer of conductive material and / or deposited conductive traces that enable the cantilever 102 and the locking pawl 130 to function as a switch.

[0028] As discussed above, FIG. 5 illustrates the unresponsive, unactivated state of indicator 10 (i.e., before the indicator is activated in the field, for example, by disengaging activation element 70). In the example where indicator 10 is used as a temperature sensor, if a thermal event or condition causes beam 106 to expand more than beam 104, this expansion would normally cause cantilever 102 to move in direction 150. However, prior to disengagement of activation element 70, activation element 70 prevents and / or limits movement of cantilever 102 in direction 150, thereby preventing the cantilever from engaging locking pawl 130. Thus, prior to disengagement of activation element 70, indicator 10 can be subjected to a thermal event that would cause activation or activation of sensor 20 without otherwise causing indicator 10 to operate.

[0029] After releasing the activation element 70, the indicator 10 is in a responsive state (i.e., capable of being activated when subjected to a temperature event). For example, in this embodiment, when exposed to a temperature event, the cantilever 102 moves in direction 150 as shown in FIG. 6. In this embodiment, the locking pawl 130 is configured such that a force exerted by the cantilever 102 on the locking pawl (e.g., surface 142 contacts surface 140) caused by the movement of the cantilever 102 in direction 150 causes the locking pawl 130 to move in direction 152, thereby allowing the cantilever 102 to pass the end 136 of the locking pawl 130. After the cantilever 102 passes the end 136 of the locking pawl 130, the locking pawl 130 returns to its original location / position (e.g., moves in a direction opposite to direction 152) as shown in FIG. 6. Thus, when the locking pawl 130 returns to its original location / position, the locking pawl 130 prevents the cantilever 102 from returning to its original or unresponsive position, thereby irreversibly activating the indicator 10.

[0030] FIG. 7 illustrates an embodiment of an actuation element 70 according to the present disclosure. In the illustrated embodiment, the blocker 74 is affixed to and / or coupled to the substrate 200 of the sensor 20. For example, in one embodiment, due to the microscale of the cantilever 102 and the desired small footprint of the overall indicator 10, the blocker 74 is also formed at a microscale and fabricated using the same MEMS fabrication techniques used to form the sensor 20. In FIG. 7, a portion of the cantilever 102 is shown adjacent to the blocker 74. Various elements associated with the actuation element 70 are not shown in FIGS. 5 and 6 to facilitate the illustration and description of the operation of the sensor 20 in conjunction with FIGS. 5 and 6. In FIG. 7, the blocker 74 is configured to be detached from the substrate 200 at a proximal end 202 of the blocker 74 relative to the substrate 200. For example, because the cantilever 102 can move when exposed to a temperature event, when the temperature event causes the cantilever 102 to transition to an actuated state, the cantilever 102 first contacts the block 74, thereby limiting the amount of movement of the cantilever 102 and preventing the amount of movement of the cantilever 102 that would otherwise cause the cantilever 102 to engage the locking pawl 130 (FIGS. 5 and 6). Thus, the block 74 is attached to the substrate 200 near the end 122 of the cantilever 102 with sufficient strength to withstand the momentum of the cantilever 102 due to potential movement of the cantilever 102 due to experiencing a temperature event.

[0031] 7 , the blocker 74 has an enlarged distal end 204 (distal to the proximal end 202) that is attached to the retaining element 72 using an adhesive layer 206, and an intermediate portion 208 that extends between the proximal end 202 and the enlarged distal end 204. Because the microsensor 20 is microscale, the enlarged distal end 204 is configured with a sufficient surface area that the adhesive layer 206 remains attached to the enlarged distal end 204 such that when the retaining element 72 is disengaged or pulled away from the sensor 20, the retaining element 72 pulls on the enlarged distal end 204, resulting in a force being applied to the proximal end 202 of the blocker 74 in a direction away from the substrate 200, causing the blocker 74 to detach from the substrate 200. In the illustrated embodiment, the proximal end 202 is configured with a smaller cross-sectional area than the enlarged distal end 204, thereby reducing the surface area of ​​the proximal end 202 that is attached to the substrate 200 and allowing the inhibitor 74 to detach from the substrate 200 when the retention element 72 is removed from the indicator 10. In certain embodiments, the proximal end 202 may be formed from a material that is more brittle than the material of the remainder of the inhibitor 74 to facilitate separation of the proximal end 202 from the substrate 200 once the retention element 72 is removed. In one embodiment, the inhibitor 74 may be undercut at the proximal end 202 to weaken the attachment of the inhibitor 74 to the substrate 200 at the proximal end 202.

[0032] Additionally, cantilever structure 102 may include additional layers / films, such as stress compensation layers, to enhance the distribution of any processing strain within cantilever structure 102. It is also within the scope of the present invention to fabricate one or both of beams 104 and 106 of cantilever structure 102 with layers that can be patterned to modify beams 104 and 106, including their response to sensed environmental parameters, such as temperature, humidity, chemicals, electromagnetic radiation, particle radiation, UV light, and / or other environmental conditions. Additionally, as noted above, beam 106 may have an outer layer of conductive material such that it can be used as a switch when contacted with a conductor on locking tab 130.

[0033] Thus, embodiments of the present disclosure enable temperature and / or temperature event detection using a small-footprint temperature indicator that employs a mechanical sensing element 100 in conjunction with a passive RFID tag that provides different readings depending on the state of a temperature switch circuit. Because the RFID tag is passive, the temperature indicator does not require a battery or other external power source. Furthermore, the temperature indicator's configuration allows the temperature indicator to become irreversible upon activation (or exposure to a temperature event of sufficient magnitude). Furthermore, temperature indicators of the present disclosure may be configured with one or more display mechanisms (e.g., a sensor 20 fabricated with an LCD panel may include a liquid that is visible within a region of the indicator 10 upon activation). Furthermore, various manufacturing processes may be used for the indicator 10 (e.g., any manufacturing process that provides one or more micromechanical structural layers with 1) conductive elements capable of making electrical contact, and 2) a movable sensing element that responds to temperature changes may be used). Examples include bulk micromachining and wafer bonding manufacturing techniques in silicon, silicon dioxide, ceramics, nickel, titanium and other conductors, LIGA-type manufacturing processes (i.e., lithography, electroplating and molding) using electroplated metals, additive manufacturing methods such as inkjet dispensing, paste screening, and other deposition methods using liquids that are subsequently solidified.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It is further understood that the terms "comprises" and / or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0035] Corresponding structure, material, acts, and all equivalents of means or steps, and functional elements in the following claims are intended to include any structure, material, or act for performing a function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or to limit the disclosure to the form disclosed. Many adjustments and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The present embodiments were chosen and described in order to best explain the principles and practical applications of the present disclosure, and to enable those skilled in the art to appreciate the disclosure of various embodiments with various adjustments suitable for the particular applications contemplated.

Claims

1. A cantilevered sensing element coupled to a support member, the sensing element having a first layer and a second layer, the first layer and the second layer defining a gap therebetween along at least a portion of their respective lengths, a first distal end of the first layer relative to the support member coupled to a second distal end of the second layer relative to the support member, the first layer and the second layer having different coefficients of expansion, the first distal end and the second distal end of the sensing element configured to move from a first position to a second position upon exposure to a temperature event; and a detection circuit configured to change from a first state to a second state in response to movement of the sensing element from the first position to the second position, the detection circuit being prevented from returning to the first state in response to the change to the second state; a microsensor having a radio frequency identification (RFID) module coupled to the detection circuit and configured to output a value indicative of the sensing element being in the second position; an activation element configured to maintain the sensing element in the first position until the activation element is removed from the microsensor; A temperature indicator.

2. A temperature indicator as described in claim 1, wherein the microsensor further has a locking element movable in a first direction in response to contact with the sensing element moving from the first position to the second position.

3. 10. The temperature indicator of claim 1, wherein the microsensor further comprises a locking element configured to prevent the sensing element from returning to the first position after being moved to the second position.

4. The temperature indicator of claim 1 , wherein the microsensor is formed on a wafer substrate.

5. The temperature indicator of claim 1 , wherein the microsensor is formed on a liquid crystal display (LCD) panel substrate.

6. The temperature indicator of claim 1 , wherein the microsensor is formed on a roll-to-roll (R2R) substrate.

7. The activation element a portion located immediately adjacent the sensing element; and an end portion positioned to displace the portion from the immediate vicinity of the sensing element under an applied force; 2. The temperature indicator of claim 1, comprising:

8. A temperature indicator comprising: a substrate having an inlay configured to communicate an operational status of the temperature indicator; a microsensor communicatively coupled to the inlay for detecting a temperature event, the microsensor having a sensing element, the microsensor having a non-reversible detection circuit configured to detect the actuation condition; an activation element configured to maintain the microsensor in a non-responsive state until removed from the temperature indicator; It is equipped with A temperature indicator wherein the sensing element is movable relative to the activation element in the unresponsive state.

9. 9. The temperature indicator of claim 8, wherein the activation element includes a retaining element coupled to a block, the retaining element disengaging the block from the microsensor when the retaining element is disengaged from the temperature indicator.

10. 10. The temperature indicator of claim 9, wherein the block is adhesively connected to the retaining element.

11. The temperature indicator of claim 8 , wherein the activation element includes a block configured to limit movement of the sensing element of the microsensor.

12. The temperature indicator of claim 8 wherein the microsensor is formed on a wafer substrate.

13. A temperature indicator comprising: a microsensor having a movable sensing element and configured to be activated upon receiving a temperature event, the microsensor having a detection circuit configured to change from a first state to a second state in response to activation of the microsensor and prevented from returning to the first state in response to the activation; a radio frequency identification (RFID) module coupled to the detection circuit and configured to output a value indicative of activation of the microsensor; an activation element configured to maintain the microsensor in a non-responsive state until removed from the microsensor; the latch movable in response to a force applied to the latch by the sensing element, the latch configured to prevent the sensing element from returning to a position corresponding to the non-responsive state of the microsensor; A temperature indicator.

14. The temperature indicator of claim 13 wherein the microsensor is formed on a wafer substrate.

15. The temperature indicator of claim 13 , wherein the microsensor is formed on a liquid crystal display (LCD) panel substrate.

16. The temperature indicator of claim 13 , wherein the activation element includes a block configured to limit movement of the sensing element of the microsensor.

17. 14. The temperature indicator of claim 13, wherein the activation element includes a retaining element coupled to a block, the retaining element disengaging the block from the microsensor when the retaining element is disengaged from the temperature indicator.

18. The temperature indicator of claim 13 , wherein the microsensor has a bimorph cantilever structure.

19. 14. The temperature indicator of claim 13, wherein the microsensor includes a locking element configured to prevent the microsensor from returning to the non-responsive state after activation.

20. 20. The temperature indicator of claim 18, wherein the detection circuit is formed on the bimorph cantilever structure.

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