A waterproof switch that is actuable by fluid and can be particularly used to activate an inhaler device

Abstract

Embodiments of the present disclosure relate to a waterproof switch that can be actuated by a fluid and can be particularly useful for activating an inhaler device. A MEMS switch can be actuated by a fluid and includes a piezoelectric pressure sensor that detects fluid movement that generates a negative pressure. A chip and a sensitive membrane of a piezoelectric pressure sensor semiconductor material are formed with a through cavity, the sensitive membrane extending over the through cavity and having a first surface and a second surface. The piezoelectric pressure sensor is mounted on a face of a plate with a through hole such that the through cavity covers the through hole and the through cavity is in fluid connection with the through hole. The plate has a fixing structure that enables the plate to be fixed in an opening of a partition wall separating a first space and a second space from each other. The plate is arranged such that the first surface of the sensitive membrane faces the first space and the second surface of the sensitive membrane faces the second space.

Description

Technical Field

[0001] This disclosure relates to a waterproof switch that can be actuated by a fluid (such as air) and is particularly useful for activating inhaler devices (such as electronic cigarettes). Background Technology

[0002] Specifically, in the following description, reference will be made to the on / off switch used in electronic cigarettes, but the same switch can also be advantageously applied to different types of inhalers (e.g., continuous positive airway pressure (CPAP) devices for sleep apnea detection), respirators, devices for detecting leaks of air or other fluids (used in industrial applications), and generally, the automotive industry.

[0003] As is well known, an inhaler is a device that enables the use of a biological respiratory system to inhale fluids (e.g., air containing nicotine, air, or aerosols containing drugs or other substances for medical or veterinary use).

[0004] In these devices, especially in cases of discontinuous use, a separate on / off mechanism is typically provided. For example, in electronic cigarettes, there is usually an accelerometer that is always active, waiting for a characteristic signal to wake up the rest of the components (e.g., a sequence of taps using a finger, so-called continuous taps). Specifically, when the accelerometer detects a sequence of taps caused by the user's finger, it generates an activation signal for a circuit that controls the evaporation of a suitable liquid solution contained in the electronic cigarette without burning the substance.

[0005] For this purpose, electronic cigarettes include an vaporization chamber or atomizer that includes, for example, a resistor formed as a winding (and therefore commonly referred to as a coil), which, when powered by a battery, heats the liquid solution directly or indirectly, thereby causing the liquid solution to evaporate.

[0006] To activate the coil, commercially available electronic cigarettes may include: a local pressure sensor that measures the pressure inside the vapor chamber; an ambient pressure sensor (barometer) that measures the pressure of the external environment; and circuitry that compares the signals generated by the sensors to determine the time it takes for the user to inhale air.

[0007] In addition, electronic cigarettes are typically equipped with indicator lights (such as LEDs) that signal when the cigarette is ready, and may also have a tail piece that lights up when inhalation is detected, thus simulating the typical red color of a traditional cigarette burning to reproduce the feeling and optical sensation of traditional smoking.

[0008] exist Figures 1 to 3 The diagram illustrates an example of a circuit used to activate the indicated type of electronic cigarette.

[0009] In detail, Figures 1 to 3 An electronic cigarette 1 is shown, which has a housing 2. The housing 2 has a larger dimension (length) along the first axis Y of the Cartesian coordinate system XYZ, and the cross-sectional area (in a plane parallel to the Cartesian plane XZ) is smaller than the length. The housing 2 includes a tubular portion 3 and an inhalation portion 4, which are arranged adjacent to each other along the first axis Y and have the same cross-section, for example, circular, rectangular, or elliptical.

[0010] The intake section 4 is open at the first end facing the tubular section 3, and has an end wall 4A ( Figure 3 The second closed end, the end wall 4A is provided with a... Figure 3 The inhalation opening 4B is shown in dashed line to allow the smoker to inhale.

[0011] The tubular portion 3 is open at both ends and is internally divided into a first part 5 and a second part 6 by a partition wall 7 that extends transversely to the tubular portion 3 (generally parallel to the Cartesian plane XZ).

[0012] The first portion 5 of the tubular section 3 is arranged near the intake section 4 and together with the intake section 4 forms an evaporation chamber 8, which houses: a slot 9, an air passage 10 surrounded by the slot 9, and a heater 11 arranged between the slot 9 and the air passage 10 near the partition wall 7. A first gap 12 extends across the entire cross-sectional area of ​​the tubular section 3 between the partition wall 7 and the bottom of the slot 9 and is fluidly connected to the air passage 10. A tubular second gap 15 is arranged between the wall of the first portion 5 of the tubular section 3 and the slot 9, and is fluidly connected to the first gap 12, and opens outward at the mutually facing ends of the tubular section 3 and the intake section 4. The second gap 15, the first gap 12, and the air passage 10 form a fluid path (indicated by arrow A) for air to be drawn in through the intake opening 4B in the end wall 4A of the intake section 4.

[0013] Air passage 10 and tank 9 are connected by one or more holes 16, which allow fluid in tank 9 to permeate toward heater 11, where the fluid is evaporated and mixed with drawn-in air. A sponge area or fabric (not shown) may be arranged near heater 11 to facilitate liquid exit from tank 9 and evaporation. In a variant (not shown), air passage 10 is not physically separate from tank 9, but tank 9 has holes at its bottom facing a first gap 12 to allow air to pass through and mix with the evaporated material, creating a virtual channel.

[0014] As detailed below, the second part 5 of the tubular section 3 forms an open chamber 17, which accommodates a plate 18 arranged longitudinally relative to the housing 2 and carries electronic components 20 to 23.

[0015] Specifically, electronic components 20 to 23 include a control unit 20, such as an ASIC or microcontroller, an accelerometer 21, an ambient pressure sensor 22, and an internal pressure sensor 23. The second portion 5 of the tubular section 3 also houses a battery 24, which is schematically shown and is electrically coupled to electronic components 20 to 23 (not shown) for powering electronic components 20 to 23.

[0016] Furthermore, as explained below, the control unit 20 is electrically coupled to all other electronic components 21 to 23 and the heater 11 (not shown) in order to receive detected movement and pressure signals and control the operation of the heater 11.

[0017] The environmental pressure sensor 22 is sensitive to the pressure present in the open chamber 17, and therefore measures the pressure in the external environment.

[0018] The internal pressure sensor 23 faces the detection channel 26 defined by a channel wall 37 extending from the partition wall 7 toward the interior of the second portion 6 of the tubular section 3. The channel wall 37 has an opening and surrounds the internal pressure sensor 23, from which a portion of the tubular wall 38 extends into the plate. A sealing gasket 27 is disposed between the internal pressure sensor 23 and this portion of the tubular wall 38, thereby sealing the fluid path of the intake air and the sensitive portion of the internal pressure sensor 23 from the open chamber 17. Furthermore, a gel mass block covers the internal pressure sensor 23 to allow it to detect pressure in the first gap 12 and protect it from any possible leakage of liquid leaving the tank 9.

[0019] The electronic cigarette 1 operates as follows. The accelerometer 21 is always on and remains waiting to identify activation sequences caused by the user, such as a series of taps on the electronic cigarette 1.

[0020] Upon detecting a tap, the accelerometer 21 sends a corresponding signal to the control unit 20. Upon recognizing a specific activation sequence, the control unit 20 activates other components, particularly the ambient pressure sensor 22 and the internal pressure sensor 23. If desired, the control unit 20 then activates an LED to signal that the electronic cigarette 1 is ready.

[0021] When the user begins to inhale through the intake opening 4B at the end wall of the intake section 4, air is drawn in from the outside along the path indicated by arrow A. The air enters the air inlet between the tubular section 3 and the intake section 4 and travels along the fluid path formed by the second gap 15, the first gap 12, and the air passage 10. Therefore, a negative pressure is created in the detection channel 26. The internal pressure sensor 23 facing the detection channel 26 detects the negative pressure and generates a corresponding signal for the control unit 20. The control unit 20 identifies the intake and activates the heater 11 based on the difference between the signals from the internal pressure sensor 23 and the ambient pressure sensor 22. Therefore, the control unit 20 heats and evaporates the liquid from the tank 9 (possibly immersed in a sponge area or fabric, not shown), thereby mixing it with the inhaled air.

[0022] This operating scheme is somewhat complex and involves high power consumption because a relatively large number of components and the accelerometer 21 are always on. Furthermore, it has a non-negligible cost.

[0023] U.S. Patent 10,334,887 describes an atomizer equipped with a single sensor arranged along the fluid path of the inhaled air and capable of detecting negative pressure generated by the inhalation. Upon detection of negative pressure, the sensor (formed from a strain gauge of the resistive or capacitive type) generates a trigger signal that is sent to a controller that controls the power supply to the heater.

[0024] This solution partially addresses the cost issue mentioned above because it uses only one sensor, and there is no consumption problem, since the sensor must always be turned on and powered to detect the pressure present in the fluid path. Summary of the Invention

[0025] Therefore, the purpose of this disclosure is to provide a device that overcomes the shortcomings of the prior art.

[0026] According to this disclosure, as defined in the appended claims, a fluid-actuable MEMS switch is provided. Attached Figure Description

[0027] To better understand this disclosure, embodiments thereof will now be described by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0028] Figure 1 This is a side view of a known electronic cigarette;

[0029] Figure 2 yes Figure 1 A portion of the electronic cigarette along Figure 3 The cross section intercepted by section line II-II in the diagram;

[0030] Figure 3 yes Figure 1 The edge of electronic cigarettes Figure 2 The longitudinal section intercepted by section line III-III in the diagram;

[0031] Figure 4 It is a cross-section of a portion of a cigarette including this switch according to one embodiment;

[0032] Figure 4 A shows Figure 4 Enlarged details;

[0033] Figure 5 It is a cross-section of a portion of a cigarette including this switch according to another embodiment;

[0034] Figures 6A to 6E Is Figure 4 and Figure 5 A top view of a possible embodiment of a piezoelectric sensor in a switch;

[0035] Figure 7 Shown in top view Figures 6C to 6E Possible connections of the sensitive part of the piezoelectric sensor;

[0036] Figure 8 yes Figures 6C to 6E Electrical connection diagram of the piezoelectric sensor;

[0037] Figure 9 yes Figures 6A to 6C The piezoelectric sensor along Figure 7 The cross section intercepted by section line IX-IX; and

[0038] Figure 10 yes Figures 6A to 6C The piezoelectric sensor along Figure 7 The cross section is taken by the section line XX in the diagram. Detailed Implementation

[0039] Figure 4 It shows having in Figures 1 to 3 The figure shows a general structure and includes a portion of an electronic cigarette 101 with a switch according to this disclosure. Therefore, the overall structure of the electronic cigarette is not reproduced in the figures, and the electronic cigarette is compared with the reference figure. Figure 1 and Figure 3 The parts that are similar to those described are indicated by the addition of 100 to the figure reference numerals.

[0040] Also here, the electronic cigarette 101 has an elongated shape in the direction parallel to the first axis Y of the Cartesian coordinate system XYZ, and includes... Figure 1 The suction section 4 shown is similar to a suction section (not shown) and a tubular section 103 that houses the switch 100. Specifically, Figure 4 A portion of the tubular section 103 is shown.

[0041] As in Figures 1 to 3 In the middle, the partition wall 107 extends transversely to the tubular portion 103 and internally divides the tubular portion 103 into a first part 105 and a second part 106.

[0042] and Figure 2 and Figure 3 Similarly, the first portion 105 of the tubular section 103 is designed as a receiving groove, an air passage, and a heater (in Figure 4 Not shown in the image, and Figures 2 to 3 (Similar to the corresponding component), and forms a gap 112 (with) Figures 2 to 3 (Similar to the first gap 12 shown), and the second portion 106 form an open chamber 117 and accommodate a detection channel 126. The open chamber 117 is designed to accommodate a battery 119 and a switch 100, with the switch 100 facing the detection channel 126.

[0043] In the illustrated embodiment, the switch 100 includes a plate 118 that extends parallel to the longitudinal direction of the electronic cigarette 101 (parallel to the plane YZ of the Cartesian coordinate system XYZ) and carries a piezoelectric pressure sensor 130 and a control unit 120 on its surface 118A.

[0044] Channel wall 137 extends from partition wall 107 toward the interior of the second portion 106 of tubular portion 103 and defines detection channel 126. Channel wall 137 has opening 136 facing plate 118. Tubular wall 138 extends from opening 136 toward plate 118 and is fixed to plate 118 via support wall 133.

[0045] exist Figure 4 In one embodiment, the support wall 133 has a generally tubular shape with a cross-section that is, for example, circular, elliptical, or polygonal. The support wall 133 surrounds the piezoelectric pressure sensor 130 and the control unit 120, and defines an area approximately equal to the area of ​​the plate 118. The support wall 133 is fixed at its first end to a surface 118A of the plate 118, and partially inserted into the tubular wall 138 at its second end. In the illustrated embodiment, near the second end of the support wall 133, the support wall 133 has a groove 134 that extends circumferentially outside the support wall 133 and accommodates a sealing gasket 135. In this way, a seal is ensured between the open chamber 117 and the detection channel 126.

[0046] However, the arrangement shown in the figure is merely exemplary, and the support wall 133 can be secured to the tubular wall 138 or directly to the opening 136 by other retaining solutions, such as by quick action, using gasket elements arranged differently.

[0047] The piezoelectric pressure sensor 130 is manufactured using MEMS technology and includes a chip 139 of a semiconductor material (such as silicon). The chip 139 has an upper surface 139A on which a membrane 142 is attached and a lower surface 139B attached to a plate 118 by an adhesive layer 141. The chip 139 has a cavity 140 extending over its entire thickness. The adhesive layer 141 has a first opening 143 at the cavity 140 and is aligned with this first opening 143. The membrane 142 is suspended above the cavity 140 and has a first surface 142A facing a detection channel 126 and a second surface 142B facing the cavity 140. The cavity 140 of the piezoelectric pressure sensor 130 faces a second opening 144 (also a through opening) on ​​the plate 118, such that the cavity 140 is in fluid communication with an open chamber 117.

[0048] The control unit 120 is arranged side by side with the piezoelectric pressure sensor 130 and is bonded to the plate 118 on the surface 118A of the plate 118 by an adhesive layer 145. The control unit 120 is formed by an ASIC (Application-Specific Integrated Circuit). The control unit 120 is connected to the piezoelectric pressure sensor 130 by a first wire 146 and to the conductive area of ​​the plate 118 (not shown) by a second wire 147.

[0049] As is known and not shown, board 118 may be formed from a standard printed circuit board made of an electrically insulating material, and board 118 may include conductive areas (not shown) for electrical connection to the following: control unit 120 (as indicated above), battery 119, and heater (not shown).

[0050] Plate 118 is covered on its surface 118A by a gel mass block 150, which also surrounds the piezoelectric pressure sensor 130 and control unit 120, thereby preventing any droplets evaporated from the electronic cigarette 101 from contacting and damaging the electronic components. The gel mass block 150 has greater elasticity than the membrane 142, but is incompressible, so as to transmit the pressure present in the detection channel 126, and therefore in the gap 112, to the membrane 142.

[0051] Therefore, the membrane 142 is subjected to pressure present in the detection channel 126 on its first surface 142A and to environmental pressure on its second surface 142B.

[0052] Membrane 142 (see also Membrane 142) Figure 4 A) is essentially formed of, for example, a support layer 151 made of epitaxially grown polycrystalline silicon and a piezoelectric stack 152 disposed on the support layer 151.

[0053] The piezoelectric stack 152 includes a core region 156 made of an insulating material (e.g., aluminum nitride (AlN)), a bottom electrode region 153 made of molybdenum (Mo), a piezoelectric region 154 made of aluminum nitride (AlN), and a top electrode region 155 made of molybdenum (Mo).

[0054] See below for reference. Figure 9 In addition to providing locations for electrical connections, the top electrode region 155 is covered by a passivation layer 171 made of aluminum nitride (AlN), and laterally covered by a piezoelectric stack 152.

[0055] also, Figure 4 A illustrates a possible electrical connection between the support layer 151 and the chip 139 via a polysilicon via 165, which extends from the support layer 151 through a connection opening 166 formed in an oxide layer 167 covering the upper surface 139A of the chip 139.

[0056] exist Figure 4 In A, chip 139 may have a thickness between 50 μm and 5000 μm, for example, 1000 μm; oxide layer 167 may have a thickness between 20 nm and 1 μm, for example, 500 nm; support layer 151 may have a thickness between 2 and 20, for example, 10 μm; core region 156 may have a thickness between 4 nm and 50 nm, for example, 35 nm; bottom electrode 153 may have a thickness between 50 nm and 200 nm, for example, 100 nm; piezoelectric region 154 may have a thickness between 0.1 μm and 5 μm, for example, 1 μm; top electrode region 155 may have a thickness between 50 nm and 500 nm, for example, 100 nm; and passivation layer 171 may have a thickness between 50 nm and 1000 nm, for example, 100 nm.

[0057] In use, when the electronic cigarette 101 is inactive, it draws a very low current because only the small input of the control unit 120 is turned on, the heater (not shown) is off, and the piezoelectric pressure sensor 130 is not energized. Furthermore, in this state, the pressure on both surfaces 142A and 142B of the membrane 142 is approximately the same, and the piezoelectric stack 152 is in a static, stress-free position, generating no electrical signal. When the smoker inhales, the air... Figure 2Arrow A in the diagram indicates flow, creating a negative pressure in detection channel 126. This establishes a pressure difference between the two surfaces 142A and 142B of membrane 142, causing deformation of membrane 142 and generating charge (i.e., current) through piezoelectric region 154. This current is supplied to control unit 120. When control unit 120 receives current from piezoelectric pressure sensor 130, it switches on and activates heater (not shown), thereby operating electronic cigarette 101.

[0058] Therefore, a switch 100 with a single piezoelectric sensor and utilizing the ability of piezoelectric materials to generate current when deformed, without requiring any power supply, enables the cigarette to be switched on, which only begins to draw a large amount of current from the battery 119 when the user inhales.

[0059] Figure 5 A switch 200 is shown that also allows for precise measurement of the negative pressure present in the detection channel 126.

[0060] about Figure 4 Switches 100 and 200 include plates carrying a piezoelectric pressure sensor and a control unit, which are again indicated by reference numerals 130 and 120, respectively. Additionally, Figure 5 The switch 200 includes a barometric pressure sensor 230 disposed on a board 118 and also manufactured using MEMS technology.

[0061] To promote understanding, Figure 5 In the switch 200, the chip 139, membrane 142, cavity 140 and adhesive layer 141 of the piezoelectric pressure sensor 130 will be referred to below as the first chip 139, the first membrane 142, the first cavity 140 and the first adhesive layer 141.

[0062] The pressure sensor 230 can be manufactured in any manner suitable for accurately detecting pressure differences. For example, it can be of capacitive type, piezoresistive type, strain gauge, etc.

[0063] The barometric pressure sensor 230 includes a second chip 239 made of, for example, a semiconductor material (such as silicon), having an upper surface 239A and a lower surface 239B. The second chip 239 is fixed to a plate 118 at its lower surface 239B via a second adhesive layer 241, and the second chip 239 has a second cavity 204 extending below and parallel to the upper surface 239A of the second chip 239. A portion of the second chip 239 disposed between the upper surface 239A and the second cavity 204 forms a second membrane 242. The second cavity 204 is embedded and connected via a hole 231 to a third opening 243 in the second adhesive layer 241 and a fourth opening 244 in the plate 118, the hole 231 extending from the lower surface 239B of the second chip 239 to the second cavity 204. The hole 231 has a diameter much smaller than that of the second cavity 204.

[0064] In addition, the second chip 239 is connected to the control unit 120 via the third wire 246 and is also surrounded by the gel mass block 150.

[0065] The pressure sensor 230 has high accuracy in detecting the pressure difference present between the detection channel 126 and the open chamber 117, and outputs a precise pressure difference signal, which is provided to the control unit 120 of the switch 200. Therefore, this precise signal can be used by the control unit 120 of the switch 200 to output precise flow information, and possibly to control additional components for adjustment purposes. Here, the pressure sensor 230, which has a non-negligible current consumption, can be activated by the control unit 120 only after the piezoelectric pressure sensor 130 has been activated; therefore, its consumption is limited only after the piezoelectric pressure sensor 130 has detected inhalation or, generally, the presence of airflow (such as causing deformation of the membrane 142).

[0066] The above solution is particularly advantageous when the switch 200 is used in medical inhalation devices or in sensors used to detect pressure loss in industrial environments, where, in addition to activating or deactivating the electronic circuitry, it is desirable for the switch to also monitor the value of pressure changes generated in the detection channel 126, but without absorbing current under inactive conditions.

[0067] Figures 6A to 6E Different possible shapes of the membrane 142 of the piezoelectric pressure sensor 130 are shown.

[0068] exist Figure 6AIn the top view, chip 139 has a square shape, support layer 151 has a circular shape with a first diameter, and piezoelectric stack 152 also has a circular shape, piezoelectric stack 152 is concentric with support layer 151 and has a smaller diameter than support layer 151.

[0069] exist Figure 6B In the middle, the support layer 151 again has a circular shape with a first diameter, and the piezoelectric stack 152 has an annular shape, the piezoelectric stack 152 is concentric with the support layer 151 and has a smaller maximum diameter than the support layer 151.

[0070] exist Figure 6C In the middle, the support layer 151 again has a circular shape with a first diameter, and the piezoelectric stack 152 is formed by four adjacently arranged circular sectors 157, having a generally circular overall shape and a smaller diameter than the support layer 151.

[0071] exist Figure 6D In the piezoelectric stack 152, four annular sectors 158 are arranged side by side to have a generally annular shape, wherein the maximum diameter is equal to that of the support layer 151.

[0072] exist Figure 6E In the piezoelectric stack 152, four annular sectors 159 are arranged side by side to have a generally annular shape, wherein the maximum diameter is smaller than that of the support layer 151.

[0073] for Figure 6E The piezoelectric pressure sensor 130, by way of example only, is shown in... Figures 7 to 9 As shown in the figure, Figures 6C to 6E The circular sector 157 and the annular sector 159 of the piezoelectric pressure sensor 130 can be connected in series (e.g., in...). Figures 7 to 9 (As shown in the image).

[0074] In detail, Figure 7 In this configuration, the annular sectors 159 are designated as first annular sector 159.1, second annular sector 159.2, third annular sector 159.3, and fourth annular sector 159.4, and are arranged side-by-side in a sequence indicated by their respective numbers. Except for the first annular sector 159.1 and the last annular sector 159, a connection area 160 extends between adjacent annular sectors. The four annular sectors are connected to corresponding first contact pads 162.1 and second contact pads 162.2 via first conductive area 161.1 and second conductive area 161.2.

[0075] See below for reference. Figure 9 Explained, the connection region 160 between two adjacent annular sectors 159 is configured to connect the bottom electrode regions of annular sectors 159.1, 159.2, and 159.3. Figure 3 or Figure 4 153) is electrically connected to the top electrode region 155 of the adjacent annular sectors 159.2, 159.3, and 159.4. See also [the diagram] in this manner. Figure 8 In electrical terms, this can be represented as annular sectors 159.1 to 159.4 of capacitors C1 to C4 connected in series between a first terminal (e.g., corresponding to the first contact pad 162.1) and a second terminal (e.g., corresponding to the second contact pad 162.2), the first terminal being grounded, and the second terminal outputting a voltage Vo related to the current generated by the piezoelectric pressure sensor 130 when a negative pressure is detected as described above.

[0076] In this way, the optimal trade-off between maximizing the total capacitance C and the output voltage Vo is achieved.

[0077] Figure 9 An embodiment of a connection region 160 between two adjacent annular sectors (e.g., first annular sector 159.1 and second annular sector 159.2) is shown.

[0078] exist Figure 9 In this structure, portions of the layers forming the stack 142 extend over the support layer 151. As can be observed, portions of the core region 156 and the bottom electrode region 153 (having the same shape) protrude from corresponding portions of the piezoelectric region 154 and the top electrode region 155. The passivation layer 171 extends over the entire surface of the film 142 and has openings 172 at the protruding portions of the bottom electrode region 153 in the second annular sector 159.2 and on the top electrode region 155 in the first annular sector 159.1. A connection region 160 extends over the passivation layer 171 and directly contacts the bottom electrode region 153 of the second annular sector 159.2 and the top electrode region 155 of the first annular sector 159.1 at the openings 172.

[0079] The connection area 160 is made of a conductive material, typically a metal, such as TiW / Au.

[0080] Figure 10 An embodiment of conductive regions 161.1 and 161.2 is shown (this figure specifically refers to the first conductive region 161.1, but the structure of the second conductive region 161.2 is the same). Specifically, conductive regions 161.1 and 161.2 are formed in the same layer of the bottom electrode region 153 (here identified as bottom electrode layer 180) as a continuation thereon. Furthermore, here, various portions of the core region 156 also extend beneath the conductive regions 161.1 and 161.2, but the conductive regions 161.1 and 161.2 are covered by the passivation layer 171.

[0081] Finally, it is clear that modifications and alterations can be made to the switches described and shown herein without departing from the scope of this disclosure as defined in the appended claims. For example, the various embodiments described can be combined to provide further solutions.

[0082] Furthermore, the shape of the sensitive part of a piezoelectric pressure sensor can change. Figures 6C to 6E The number of circular sectors 157 and annular sectors 159 in the piezoelectric pressure sensor 130 shown may not be four.

[0083] This switch can be used in inhalation devices or leak detection devices that are different from the electronic cigarettes described.

[0084] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments based on the detailed description above. Generally, the terminology used in the following claims should not be construed as limiting the claims to the specific embodiments disclosed in this specification and claims, but should be interpreted to include all possible embodiments and the full scope of equivalents granted by such claims. Therefore, the claims are not limited to this disclosure.

Claims

1. A device for detecting discontinuous passage of a fluid, the device having an elongated shape and comprising: a housing having a tubular shape; a partition wall dividing the housing into a first portion and a second portion; a passage wall extending from the partition wall towards the interior of the second portion and delimiting a detection passage; a MEMS switch actuatable by the fluid, comprising: a piezoelectric pressure sensor; a plate having a face and a through hole, wherein the piezoelectric pressure sensor is fixed to the face of the plate and comprises: a chip of semiconductor material having a through cavity covering the through hole and being in fluid connection with the through hole, and a sensitive membrane extending over the through cavity and having a first surface and a second surface; a support wall configured to fix the plate in an opening of the partition wall; and a tubular wall extending from the opening towards the plate and being fixed to the plate via the support wall, the tubular wall separating the detection passage and an open chamber from each other, wherein the first surface of the sensitive membrane faces the detection passage and the second surface of the sensitive membrane faces the open chamber.

2. The apparatus of claim 1, wherein, the sensitive membrane comprises a piezoelectric stack comprising a bottom electrode region, a piezoelectric region and a top electrode region.

3. The apparatus of claim 2, wherein, the piezoelectric stack has a circular shape, a ring shape, a circular shape having a plurality of sectors or a ring shape having a plurality of sectors.

4. The apparatus of claim 2, wherein, the piezoelectric stack comprises a plurality of serially connected sectors adjacent to each other but not in contact, wherein a top electrode portion of a first sector of the plurality of sectors is electrically coupled to a bottom electrode portion of a second sector adjacent to the first sector, a bottom electrode portion of the first sector and a top electrode portion of a last sector of the plurality of sectors are coupled to external terminals of the piezoelectric pressure sensor.

5. The apparatus of claim 1, wherein, the support wall has a tubular shape, surrounds the piezoelectric pressure sensor and has a first end and a second end, the first end of the support wall is joined to the face of the plate and the second end of the support wall has a retaining member configured to be sealingly coupled to the partition wall.

6. The apparatus of claim 5, wherein, the retaining member comprises a groove in the support wall and a sealing grommet is positioned within the groove.

7. The apparatus of claim 1, further comprising: a gel layer coats the piezoelectric pressure sensor and the face of the plate within a space defined by the support wall.

8. The apparatus of claim 1, further comprising: a control unit is joined to the face of the plate, the control unit is electrically coupled to the piezoelectric pressure sensor and is configured to detect a deformation of the sensitive membrane of the piezoelectric pressure sensor.

9. The apparatus of claim 1, further comprising: a barometric pressure sensor is joined to the face of the plate.

10. The apparatus of claim 9, wherein, the barometric pressure sensor is a MEMS sensor comprising at least one of: a capacitive sensor, a resistive sensor or a strain gauge.

11. A device comprising: a housing; a partition wall dividing the housing into a first portion and a second portion; a passage wall extending from the partition wall towards the interior of the second portion and delimiting a detection passage; and a MEMS switch actuatable by the fluid, comprising: a piezoelectric pressure sensor; A MEMS switch, comprising: a piezoelectric pressure sensor; a plate having a face and a through hole, wherein the piezoelectric pressure sensor is fixed to the face of the plate and the piezoelectric pressure sensor comprises: a chip of a semiconductor material having a through cavity covering the through hole and the through cavity is in fluid connection with the through hole, and a sensitive membrane extending over the through cavity and having a first surface and a second surface; a support wall configured to fix the plate in an opening of the partition wall; and a tubular wall extending from the opening towards the plate and fixed to the plate via the support wall, the tubular wall separating the detection channel and the open chamber from each other, wherein the first surface of the sensitive membrane faces the detection channel and the second surface of the sensitive membrane faces the open chamber, wherein the device is configured to detect a discontinuous passage of a fluid.

12. The apparatus of claim 11, wherein, The sensitive membrane comprises a piezoelectric stack comprising a bottom electrode region, a piezoelectric region and a top electrode region.

13. The apparatus of claim 12, wherein, The piezoelectric stack has a circular shape, a ring shape, a circular shape having a plurality of sectors or a ring shape having a plurality of sectors.

14. The apparatus of claim 11, wherein, The support wall has a tubular shape, surrounds the piezoelectric pressure sensor and has a first end and a second end, the first end of the support wall is joined to the face of the plate and the second end of the support wall is configured to be sealingly coupled to the partition wall.

15. The apparatus of claim 14, wherein, The second end of the support wall comprises a recess and a sealing gasket is positioned within the recess.

16. The apparatus of claim 11, further comprising: A gel layer coats the piezoelectric pressure sensor and the face of the plate within a space defined by the support wall.

17. The apparatus of claim 11, further comprising: A control unit is joined to the face of the plate, the control unit is electrically coupled to the piezoelectric pressure sensor and the control unit is configured to detect a deformation of the sensitive membrane of the piezoelectric pressure sensor.

18. An electronic cigarette, comprising: a housing; a partition wall dividing the housing into a first portion and a second portion; a channel wall extending from the partition wall towards an interior of the second portion and delimiting a detection channel; and a MEMS switch, comprising: a piezoelectric pressure sensor; a plate having a face and a through hole, wherein the piezoelectric pressure sensor is fixed to the face of the plate and the piezoelectric pressure sensor comprises: a chip of a semiconductor material having a through cavity covering the through hole and the through cavity is in fluid connection with the through hole, and a sensitive membrane extending over the through cavity and having a first surface and a second surface; and a support wall configured to fix the plate in an opening of the partition wall; and a tubular wall extending from the opening towards the plate and fixed to the plate via the support wall, the tubular wall separating the detection channel and the open chamber from each other, wherein the first surface of the sensitive membrane faces the detection channel and the second surface of the sensitive membrane faces the open chamber. ​ 19. The electronic cigarette of claim 18, further comprising: a layer of gel, within the space delimited by the support wall, the layer of gel coating the face of the plate and the piezoelectric pressure sensor.

20. The electronic cigarette of claim 18, further comprising: a control unit, joined to the face of the plate, the control unit being electrically coupled to the piezoelectric pressure sensor and the control unit being configured to detect the deformation of the sensitive membrane of the piezoelectric pressure sensor.

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