Adjustable sensing capacitance microelectromechanical system (MEMS) apparatus

The disclosure relates to a microelectromechanical system (MEMS) sensor, more particularly to a MEMS apparatus with adjustable sensing capacitance.

A MEMS apparatus is a device that converts measured variation of physical quantity into the variation of capacitance. The MEMS apparatus can work as a variable capacitor. Because of the characteristics of simple structure, small size, high sensitivity, high resolution and non-contact measurement, the MEMS apparatus is widely used in the sensors for detecting the variation of mechanical physical quantity such as displacement, acceleration, vibration, pressure, pressure difference and liquid height.

A conventional capacitive MEMS apparatus includes an upper electrode and a lower electrode, one of which is a fixed electrode, and the other is a movable electrode. When an external force is applied on the movable electrode, the movable electrode is deformed so as to move toward to the fixed electrode. The capacitance of the capacitive MEMS apparatus is effected by the distance between the fixed electrode and the movable electrode. The capacitance is changed by a certain amount of change in the distance between the two electrodes, and thus an electrical potential difference between the two electrodes is changed. By reading the electrical potential before and after the deformation of movable electrode, a user can estimate the degree of the variation of physical quantity.

Because of increasing demand for micro detection, the capacitive MEMS apparatus is required to highly sensitive for detecting small variation of physical quantity. Generally, it is desirable that a small variation of distance between the fixed electrode and the movable electrode will generate obvious variation of electrical potential difference, such that the sensitivity of the MEMS apparatus is improved. However, if a capacitive MEMS apparatus for micro detection is used to detect large variation of physical quantity, an overly large variation of electrical potential difference may burn out integrated circuits in the capacitive MEMS apparatus. Therefore, the conventional MEMS apparatus for micro detection is inapplicable to the detection of large variation of physical quantity.

The present disclosure provides a MEMS apparatus with adjustable sensing capacitance, which the sensing capacitance can be adjusted appropriately. It enables the MEMS apparatus in the present disclosure to detect small variation of first physical quantity or to detect large variation of second physical quantity by adjusting the sensing capacitance.

According to one aspect of the present disclosure, a microelectromechanical system apparatus with adjustable sensing capacitance includes an application specific integrated circuit (ASIC) and a sensing component. The ASIC includes a top surface, a readout circuit and a plurality of electrical switches. The sensing component is configured to detect a physical quantity. The sensing component includes a fixed electrode and a movable electrode. The fixed electrode includes a plurality of electrode units, and the movable electrode is able to move relative to the fixed electrode. The electrical switches are electrically coupled to respective electrode units, and a sensing capacitance of the sensing component is adjusted when a working status of one of the electrode units is controlled by corresponding one of the electrical switches.

According to another aspect of the present disclosure, a microelectromechanical system apparatus with adjustable sensing capacitance includes a substrate, an ASIC, a first sensing component configured to detect a first physical quantity and a second sensing component configured to detect a second physical quantity. The ASIC is disposed on the substrate, and the ASIC includes a readout circuit, a plurality of first electrical switches and a plurality of second electrical switches. The first sensing component is disposed on the substrate, and the first sensing component includes a first fixed electrode and a first movable electrode movable. The first fixed electrode includes a plurality of first electrode units. The first movable electrode is able to move relative to the first fixed electrode. The first electrical switches are electrically coupled to respective first electrode units, and a sensing capacitance of the first sensing component is adjusted when a working status of one of the first electrode units is controlled by corresponding one of the first electrical switches.

The second sensing component is disposed on the substrate and the second sensing component includes a second fixed electrode and a second movable electrode. The second fixed electrode includes a plurality of second electrode units. The second movable electrode is able to move relative to the second fixed electrode. The second electrical switches are electrically coupled to respective second electrode units, and a sensing capacitance of the second sensing component is adjusted when a working status of one of the second electrode units is controlled by corresponding one of the second electrical switches.

According to the MEMS apparatus with adjustable sensing capacitance of the present disclosure, the electrical switches are electrically coupled to respective electrode units, such that the working status of one electrode unit is controlled by corresponding one electrical switch. The sensing capacitance of the MEMS apparatus is able to be adjusted by independently controlling the working status of the electrode units. The MEMS apparatus with adjustable sensing capacitance is favorable for precisely detecting the variation of physical quantity as well as preventing the ASIC from breaking down. When the MEMS apparatus is required to detect small variation of physical quantity, most of the electrode units is in the turn-on state (a working status in which the electrode unit is supplied with electric charge). When the MEMS apparatus is required to detect large variation of physical quantity, few electrode units is in the turn-on state so as to prevent the readout circuit of the ASIC from malfunction.

The above description of the summary and the description of the following embodiments are provided to illustrate and explain the spirit and principles of this disclosure, and to provide further explanation of the scope of this disclosure.

FIG. 1 is a perspective view of a MEMS apparatus with adjustable sensing capacitance according to a first embodiment of the present disclosure;

FIG. 2 is a schematic view showing electrical connection between an ASIC and multiple electrode units of the MEMS apparatus with adjustable sensing capacitance in FIG. 1 ,

FIG. 3 is a schematic view showing working status of the electrode units when a small variation of physical quantity is detected by the MEMS apparatus with adjustable sensing capacitance in FIG. 1 ;

FIG. 4 is a schematic view showing working status of the electrode units when a larger variation of physical quantity is detected by the MEMS apparatus with adjustable sensing capacitance in FIG. 1 ;

FIG. 5 is a perspective view of a MEMS apparatus with adjustable sensing capacitance according to a second embodiment of the present disclosure;

FIG. 6 is a top view of the MEMS apparatus with adjustable sensing capacitance in FIG. 5 ;

FIG. 7 is a perspective and cross-sectional view of a MEMS apparatus with adjustable sensing capacitance according to a third embodiment of the present disclosure;

FIG. 8 is a perspective and cross-sectional view of a MEMS apparatus with adjustable sensing capacitance according to a fourth embodiment of the present disclosure;

FIG. 9 is a cross-sectional view of the MEMS apparatus with adjustable sensing capacitance in FIG. 8 ;

FIG. 10 is a perspective view of a MEMS apparatus with adjustable sensing capacitance according to a fifth embodiment of the present disclosure; and

FIG. 11 is a schematic view showing electrical connection between an ASIC and multiple electrode units of the MEMS apparatus with adjustable sensing capacitance in FIG. 10 .

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

According to one embodiment of the present disclosure, a MEMS sensor includes an ASIC, a fixed electrode and a movable electrode. Please refer to FIG. 1 , which is a perspective view of a MEMS apparatus with adjustable sensing capacitance according to a first embodiment of the present disclosure. In this embodiment, a MEMS apparatus with adjustable sensing capacitance 1 includes an ASIC 10 and a sensing component 11 .

The ASIC 10 is an integrated circuit chip customized for a particular use. The ASIC 10 includes a top surface 110 .

The sensing component 11 includes a fixed electrode 20 and a movable electrode 30 . The fixed electrode 20 is disposed on the top surface 110 of the ASIC 10 . The fixed electrode 20 includes a plurality of electrode units 210 spaced apart from each other. The electrode unit 210 , for example, is a conductive metal pad disposed on the top surface 110 of the ASIC 10 . It is worth noting that the present disclosure is not limited by the number of the electrode units 210 depicted in FIG. 1 .

The movable electrode 30 is able to move relative to the fixed electrode 20 . In detail, the movable electrode 30 includes a fixed portion 310 and a movable portion 320 connected to each other. The fixed portion 310 is disposed on the top surface 110 of the ASIC 10 , and the movable portion 320 corresponds to the electrode units 210 . One end of the movable portion 320 of the movable electrode 30 is connected to the fixed portion 310 , and opposite end of the movable portion 320 overhangs the electrode units 210 . When the movable portion 320 is deformed by an external force applied on the movable electrode 30 , the overhung end of the movable portion 320 moves relative to the fixed electrode 20 so as to be toward or away from the electrode units 210 , and thus a distance between the electrode unit 210 and the overhung end of the movable portion 320 is changed. A sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 is adjusted by changing the distance between the electrode unit 210 and the overhung end of the movable portion 320 .

Please further refer to FIG. 2 , which is a schematic view showing electrical connection between an ASIC and electrode units of the MEMS apparatus with adjustable sensing capacitance in FIG. 1 . In this embodiment, the ASIC 10 further includes a readout circuit 120 and a plurality of electrical switches 130 . The number of the electrical switches 130 corresponds to the number of the electrode units 210 .

The readout circuit 120 is electrically coupled to the electrode units 210 of the fixed electrode 20 in order to read an electrical potential difference between the fixed electrode 20 and the movable electrode 30 , thereby obtaining the capacitance of the MEMS apparatus with adjustable sensing capacitance 1 .

The electrical switches 130 are electrically coupled to respective electrode units 210 of the fixed electrode 20 , and each electrical switch 130 is configured to control a working status of respective electrode unit 210 . In one embodiment, the electrical switch 130 is a capacitance sensing switch. In another embodiment, electrical switch 130 is a resettable fuse switch.

The working status of the electrode unit 210 includes a turn-on state and a turn-off state. When the electrical switch 130 of the ASIC 10 is switched on such that the ASIC 10 is able to supply electric charge to the electrode unit 210 through respective electrical switch 130 , this electrode unit 210 is in the turn-on state. In the turn-on state, the electrical potential difference is existed between the fixed electrode 20 and the movable electrode 30 . On the contrary, when the electrical switch 130 is switched off such that the ASIC 10 is unable to supply electric charge to the electrode unit 210 , this electrode unit 210 is in the turn-off state. In the turn-off state, there is no electrical potential difference between the fixed electrode 20 and the movable electrode 30 . A sensing capacitance of the sensing component 11 is adjusted when the working status of one of the electrode units 210 is controlled by corresponding one of the electrical switches 130 . More specifically, one of the electrode units 210 is in the turn-on state when the ASIC 10 supplies electric charge to this electrode unit 210 through corresponding one of the electrical switches 130 . One of the electrode units 210 is in the turn-off state when the ASIC 10 does not supply electric charge to this electrode unit 210 .

The present disclosure is not limited by the aforementioned specific method of controlling the working status of the electrode unit 210 by electrical switch 130 . For example, a user may manually control the electrical switch 130 to determine whether the ASIC supplies electric charge to respective electrode unit 210 ; or, the electrical switch 130 is automatically controlled by an operating instruction in an external register (not shown in the drawings) to determine whether the ASIC supplies electric charge to respective electrode unit 210 .

A method of detecting a variation of physical quantity by the MEMS apparatus with adjustable sensing capacitance 1 is described hereafter. Please refer to FIG. 3 and FIG. 4 . FIG. 3 is a schematic view showing working status of the electrode units when a small variation of physical quantity is detected by the MEMS apparatus with adjustable sensing capacitance in FIG. 1 . FIG. 4 is a schematic view showing working status of the electrode units when a larger variation of physical quantity is detected by the MEMS apparatus with adjustable sensing capacitance in FIG. 1 . In FIG. 3 and FIG. 4 , the electrode units 210 in dark color are in the turn-off state, while the electrode units 210 in white color are in the turn-on state.

According to one embodiment of the present disclosure, the electrical switches 130 control respective electrode units 210 of the fixed electrode 20 . More specifically, several electrode units 210 of the fixed electrode 20 are arranged on the top surface 110 of the ASIC 10 so as to form an electrode assembly. According to the working status of each electrode unit 210 in the electrode assembly, the electrode units 210 are grouped in electrode assemblies. FIG. 3 and FIG. 4 show a 4×4 (4 rows by 4 columns) electrode units array, while the present disclosure is not limited by number of rows and number of columns of the electrode units array.

In FIG. 3 , the electrode units 210 are grouped in electrode assemblies 21 , 22 , 23 and 24 . In this embodiment, each of the electrode assemblies 21 , 22 , 23 and 24 includes multiple electrode units 210 arranged along Y-axis. Each of the electrical switches 130 can be switched on by the control of the ASIC 10 , such that electric charge can flow to the electrode units 210 of the electrode assemblies 21 , 22 and 23 through respective electrical switches 130 , and thus each of electrode units 210 in the electrode assemblies 21 , 22 and 23 is in the turn-on state. Meanwhile, each of the electrical switches 130 can be switched off by the control of the ASIC 10 , such that electric charge cannot flow to the electrode units 210 of the electrode assembly 24 through respective electrical switches 130 , and thus each electrode unit 210 of the electrode assembly 24 is in the turn-off state.

In FIG. 4 , the electrode units 210 are grouped in electrode assemblies 25 , 26 , 27 and 28 . Similarly, some electrical switches 130 can be switched on by the control of the ASIC 10 so as to supply electric charge to the electrode units 210 of the electrode assembly 25 through respective electrical switches 130 , and thus each electrode unit 210 of the electrode assembly 25 is in the turn-on state. Meanwhile, the other electrical switches 130 can be switched off by the control of the ASIC 10 so as to be unable to supply electric charge to the electrode units 210 of the electrode assemblies 26 , 27 and 28 , and thus each electrode unit 210 of the electrode assemblies 26 , 27 and 28 is in the turn-off state.

The present disclosure is not limited by the arrangement of the electrode assemblies depicted in FIG. 3 and FIG. 4 . In another embodiment, the electrode units 210 of two adjacent electrode assemblies are all in the turn-on state, and the electrode units 210 of the other two adjacent electrode assemblies are all in the turn-off state. In still another embodiment, all electrode units 210 can be in the turn-on state.

As mentioned above, some electrical switches 130 of the ASIC 10 are respectively controlled to be switched on, such that ASIC 10 can supply electric charge to respective electrode units 210 through respective electrical switches 130 . The other electrical switches 130 are respectively controlled to be switched off, such that these electrical switches 130 are unable to supply electric charge to respective electrode units 210 . By controlling the working status of the electrode units 210 or the electrode assemblies, the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 can be adjusted. Thus, the MEMS apparatus with adjustable sensing capacitance 1 is applicable to detect different physical quantities, thereby preventing the ASIC 10 from malfunction due to overly larger sensing capacitance.

For exemplary illustration, an application of the MEMS apparatus with adjustable sensing capacitance 1 for detecting pressure is described in the following paragraphs, while the present disclosure is not limited by the specific physical quantity mentioned above. For examples, the MEMS apparatus with adjustable sensing capacitance 1 can be applied to detect various physical quantities such as displacement, acceleration, vibration and atmospheric pressure.

Firstly, the application of the MEMS apparatus with adjustable sensing capacitance 1 for detecting small pressure variation (for example, a pressure variation of 100˜1000 Pascal) is described. When the pressure is applied on the movable electrode 30 of the MEMS apparatus with adjustable sensing capacitance 1 , the movable portion 320 is deformed such that the distance between the movable portion 320 and the electrode unit 210 is changed. Since a smaller pressure applied on the movable electrode 30 , there is a small variation of the distance between the movable portion 320 and the electrode unit 210 . At this time, in order to make the readout circuit 120 of the ASIC 10 successfully read higher sensing capacitance out, it is required that the MEMS apparatus with adjustable sensing capacitance 1 should have higher sensitivity. As shown in FIG. 3 , three groups of the electrical switches 130 control the working status of the electrode units 210 in respective electrode assemblies 21 , 22 and 23 , such that these electrode units 210 are in the turn-on state. Meanwhile, the other group of the electrical switches 130 controls the working status of the electrode units 210 in the electrode assembly 24 , such that these electrode units 210 are in the turn-off state. When detecting small pressure variation, the MEMS apparatus with adjustable sensing capacitance 1 is with higher sensing capacitance since most of the electrode units 210 are in the turn-on state. At that moment, a small variation of the distance between the movable portion 320 and the electrode unit 210 will generate relatively large variation of electrical potential difference. Therefore, the MEMS apparatus with adjustable sensing capacitance 1 in FIG. 3 , with most of the electrode units 210 in the turn-on state, is suitable for the detection of small pressure variation.

However, the MEMS apparatus with adjustable sensing capacitance 1 in FIG. 3 is not suitable to detect larger pressure variation (for example, a pressure variation of larger than 10 5 Pascal). When a large pressure is applied on the movable electrode 30 , the readout circuit 120 may break down due to overly high sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 . Thus, it is required to adjust the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 by changing the working status of the electrode unit 210 .

As shown in FIG. 4 , one group of the electrical switches 130 controls the working status of the electrode units 210 in the electrode assembly 25 , such that these electrode units 210 are in the turn-on state. Meanwhile, the other three groups of the electrical switches 130 control the working status of the electrode units 210 in respective electrode assemblies 26 , 27 and 28 , such that these electrode units 210 are in the turn-off state. The MEMS apparatus with adjustable sensing capacitance 1 is with lower sensing capacitance since few electrode units 210 are in the turn-on state. At this moment, even though a large variation of the distance between the movable portion 320 and the electrode unit 210 , a capacitance variation generated by the variation of distance is not overly large, thereby preventing the readout circuit 120 from breaking down. Therefore, the MEMS apparatus with adjustable sensing capacitance 1 in FIG. 4 , with most of the electrode units 210 in the turn-off status, is suitable for the detection of large pressure variation.

According to the present disclosure, the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 is able to be adjusted by making the electrical switches 130 control the working status of respective electrode units 210 . The user or a control system can increase or decrease the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 according to the physical quantity proposed to be detected. As to the detection of small variation of the physical quantity, most of the electrode units 210 are in the turn-on state so as to increase the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 , and thus the capacitance variation between the fixed electrode 20 and the movable electrode 30 can be successfully read. As to the detection of large variation of the physical quantity, few electrode units 210 are in the turn-on state so as to decrease the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 , and thus the readout circuit 120 is prevented from breaking down due to overly large variation of physical quantity.

Other embodiments of the MEMS apparatus with adjustable sensing capacitance are disclosed in the following paragraphs. FIG. 5 is a perspective view of a MEMS apparatus with adjustable sensing capacitance according to a second embodiment of the present disclosure. FIG. 6 is a top view of the MEMS apparatus with adjustable sensing capacitance in FIG. 5 . In this embodiment, a MEMS apparatus with adjustable sensing capacitance 1 a includes an ASIC 10 and a sensing component 11 a . The detail description of the ASIC 10 can be referred to the first embodiment, and will be omitted hereafter.

The ASIC 10 includes a top surface 110 , a readout circuit and a plurality of electrical switches. The sensing component 11 a includes a fixed electrode 20 a and a movable electrode 30 a . The fixed electrode 20 a includes a plurality of first electrode units 210 a spaced apart from each other and a plurality of second electrode units 220 a spaced apart from each other.

The first electrode units 210 a and the second electrode units 220 a are disposed on the top surface 110 of the ASIC 10 . The readout circuit is electrically coupled to the first electrode units 210 a and the second electrode units 220 a in order to read an electrical potential difference between the fixed electrode 20 a and the movable electrode 30 a . Some of the electrical switches are electrically coupled to respective first electrode units 210 a , and the other electrical switches are electrically coupled to respective second electrode units 220 a . Each electrical switch is configured to control a working status of respective first electrode unit 210 a or a working status of respective second electrode unit 220 a . It is worth noting that the present disclosure is not limited by the number of the first electrode units 210 a and that of the second electrode units 220 a.

The movable electrode 30 a includes a fixed portion 310 a , a movable portion 320 a and a flexible portion 330 a connected to each other. The fixed portion 310 a is disposed on the top surface 110 of the ASIC 10 , and the movable portion 320 a is connected to the fixed portion 310 a via the flexible portion 330 a . The first electrode units 210 a and the second electrode units 220 a are respectively located on opposite sides of the movable portion 320 a . The movable electrode 30 a is able to move relative to the fixed electrode 20 a along a direction perpendicular to a normal line of the top surface 110 .

In this embodiment, a configuration including the fixed electrode 20 a and the movable electrode 30 a forms a comb-electrode structure. As shown in FIG. 6 , each of the first electrode units 210 a includes a plurality of first electrode fingers 211 a , and each of the second electrode units 220 a includes a plurality of second electrode fingers 221 a . The movable portion 320 a of the movable electrode 30 a includes a plurality of third electrode fingers 321 a . When the movable portion 320 a moves relative to the fixed electrode 20 a , the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 a is changed. The sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 a is able to be adjusted by making the ASIC 10 control the working status of each of the first electrode unit 210 a and the second electrode unit 220 a . The sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 a is increased or decreased according to the degree of variation of the physical quantity.

FIG. 7 is a perspective and cross-sectional view of a MEMS apparatus with adjustable sensing capacitance according to a third embodiment of the present disclosure. In this embodiment, a MEMS apparatus with adjustable sensing capacitance 1 b includes an ASIC 10 and a sensing component 11 b . The detail description of the ASIC 10 can be referred to the first embodiment, and will be omitted hereafter.

The ASIC 10 includes a top surface 110 , a readout circuit and a plurality of electrical switches. The sensing component 11 b includes a fixed electrode 20 and a movable electrode 30 b , and the fixed electrode 20 includes a plurality of electrode units 210 spaced apart from each other.

The electrode units 210 are disposed on the top surface 110 of the ASIC 10 . The readout circuit is electrically coupled to the electrode units 210 in order to read an electrical potential difference between the fixed electrode 20 and the movable electrode 30 b . The electrical switches are electrically coupled to respective electrode units 210 , and each electrical switch is configured to control a working status of respective electrode unit 210 .

The fixed portion 310 b of the movable electrode 30 b surrounds the electrode units 210 of the fixed electrode 20 . The movable portion 320 b of the movable electrode 30 b overhangs the electrode units 210 . The movable electrode 30 b is bonded with the ASIC 10 to form a hermetic chamber in which the electrode units 210 are accommodated. Therefore, it is favorable for preventing the electrode units 210 from dust in the air.

In this embodiment, the MEMS apparatus with adjustable sensing capacitance 1 b with adjustable sensing capacitance is suitable to be used as an altimeter. When the MEMS apparatus with adjustable sensing capacitance 1 b is applied to determine an altitude variation of object above a fixed level, most of the electrode units 210 are controlled by the electrical switches so as to be in the turn-on state. Therefore, when the atmospheric pressure slightly changes due to altitude change, the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 b can be adjusted to obtain higher value, and thus the ASIC 10 can precisely calculate the altitude change.

In this embodiment, the MEMS apparatus with adjustable sensing capacitance 1 b with adjustable sensing capacitance is also suitable to be used as a barometer. When the MEMS apparatus with adjustable sensing capacitance 1 b is configured to detect high pressure gas, most of the electrode units 210 are controlled by the electrical switches so as to be in the turn-off state. Therefore, when the barometer is configured to detect high pressure gas in a container, the sensing capacitance of the MEMS apparatus with adjustable sensing capacitance 1 b can be adjusted to obtain lower value so as to prevent the ASIC 10 from breaking down.

Please refer to FIG. 8 and FIG. 9 . FIG. 8 is a perspective and cross-sectional view of a MEMS apparatus with adjustable sensing capacitance according to a fourth embodiment of the present disclosure. FIG. 9 is a cross-sectional view of the MEMS apparatus with adjustable sensing capacitance in FIG. 8 . In this embodiment, a MEMS apparatus with adjustable sensing capacitance 1 c includes an ASIC 10 and a sensing component 11 c . The detail description of the ASIC 10 can be referred to the first embodiment, and will be omitted hereafter.

The ASIC 10 includes a top surface 110 , a readout circuit and a plurality of electrical switches. The sensing component 11 c includes a fixed electrode 20 c and a movable electrode 30 c.

The fixed electrode 20 c includes a central electrode unit 210 c and a plurality of annular electrode units 220 c spaced apart from each other, and each of the annular electrode units 220 c surrounds the central electrode unit 210 c . In detail, the annular electrode units 220 c and the central electrode unit 210 c are arranged concentrically. The central electrode unit 210 c and the annular electrode units 220 c are disposed on the top surface 110 of the ASIC 10 . The readout circuit is electrically coupled to the central electrode unit 210 c and the annular electrode units 220 c in order to read an electrical potential difference between the fixed electrode 20 c and the movable electrode 30 c . One of the electrical switches is electrically coupled to the central electrode unit 210 c , and the other electrical switches are electrically coupled to respective annular electrode units 220 c . The electrical switch is configured to control a working status of the central electrode unit 210 c or a working status of respective annular electrode unit 220 c . It is worth noting that the present disclosure is not limited by the number of the annular electrode units 220 c.

The fixed portion 310 c of the movable electrode 30 c surrounds the central electrode unit 210 c and the annular electrode units 220 c of the fixed electrode 20 c . The movable portion 320 c of the movable electrode 30 c overhangs the central electrode unit 210 c and the annular electrode units 220 c.

Please refer to FIG. 10 and FIG. 11 . FIG. 10 is a perspective view of a MEMS apparatus with adjustable sensing capacitance according to a fifth embodiment of the present disclosure. FIG. 11 is a schematic view showing electrical connection between an ASIC and multiple electrode units of the MEMS apparatus with adjustable sensing capacitance in FIG. 10 .

In this embodiment, a MEMS apparatus with adjustable sensing capacitance 1 d includes a substrate 2 d , an ASIC 10 d , a first sensing component 11 d and a second sensing component 11 e.

The substrate 2 d , for example, is a silicon substrate including a top surface 21 . The ASIC 10 d , the first sensing component 11 d and the second sensing component 11 e are disposed on the top surface 21 of the substrate 2 d.

The first sensing component 11 d includes a first fixed electrode 20 d and a first movable electrode 30 d . The first fixed electrode 20 d includes a plurality of first electrode units 210 d space apart from each other. The first movable electrode 30 d includes a first fixed portion 310 d and a first movable portion 320 d . The first fixed portion 310 d is disposed on the substrate 2 d and surrounds the first electrode units 210 d . The first movable portion 320 d overhangs the first electrode units 210 d . The first movable electrode 30 d is bonded with the ASIC 10 d to form a hermetic chamber in which the first electrode units 210 d are accommodated. When an external force is applied on the first movable electrode 30 d to deform the first movable portion 320 d , the first movable portion 320 d moves relative to the first fixed electrode 20 d so as to change a distance between the first movable portion 320 d and the first electrode unit 210 d , thereby changing a sensing capacitance between the first fixed electrode 20 d and the first movable electrode 30 d.

The second sensing component 11 e includes a second fixed electrode 20 e and a second movable electrode 30 e . The second fixed electrode 20 e includes a plurality of second electrode units 210 e space apart from each other. The second movable electrode 30 e includes a plurality of second fixed portions 310 e and a second movable portion 320 e . The second fixed portions 310 e are disposed on the substrate 2 d , and the second movable portion 320 e is located between the second fixed portions 310 e . The second movable portion 320 e includes a movable mass 321 e and a plurality of elastic components 322 e , and each of the elastic components 322 e is located between the movable mass 321 e and respective second fixed portion 310 e . The movable mass block 321 e is connected to the second fixed portion 310 e via the elastic component 322 e , and the movable mass 321 e overhangs the second electrode units 210 e . The movable mass 321 e is able to move relative to the second fixed electrode 20 e so as to change a sensing capacitance between the second fixed electrode 20 e and the second movable electrode 30 e.

The ASIC 10 d includes a readout circuit 120 d , a plurality of first electrical switches 130 d and a plurality of second electrical switches 130 e . The number of the first electrical switches 130 d corresponds to that of the first electrode units 210 d . Similarly, the number of the second electrical switches 130 e corresponds to that of the second electrode units 210 e . The readout circuit 120 d is electrically coupled to the first electrode units 210 d in order to read an electrical potential difference between the first fixed electrode 20 d and the first movable electrode 30 d , thereby obtaining the capacitance of the first sensing component 11 d . Moreover, the readout circuit 120 d is also electrically coupled to the second electrode units 210 d in order to read an electrical potential difference between the second fixed electrode 20 d and the second movable electrode 30 d , thereby obtaining the capacitance of the second sensing component 11 e.

The first electrical switches 130 d are electrically coupled to respective first electrode units 210 d , and each of the first electrical switches 130 d is configured to control a working status of respective first electrode unit 210 d . Moreover, the second electrical switches 130 e are electrically coupled to respective second electrode units 210 e , and each of the second electrical switches 130 e is configured to control a working status of respective second electrode unit 210 e.

The working status of the first electrode unit 210 d and the second electrode unit 210 e includes a turn-on state and a turn-off state. When the first electrical switch 130 d of the ASIC 10 d is switched on such that the ASIC 10 d is able to supply electric charge to the first electrode unit 210 d through respective first electrical switch 130 d , this first electrode unit 210 d is in the turn-on state. Similarly, when the second electrical switch 130 e of the ASIC 10 d is switched on such that the ASIC 10 d is able to supply electric charge to respective second electrode unit 210 e , this second electrode unit 210 e is in the turn-on state. In the turn-on state, the electrical potential difference is existed between the first fixed electrode 20 d and the first movable electrode 30 d or between the second fixed electrode 20 e and the second movable electrode 30 e.

On the contrary, when the first electrical switch 130 d is switched off such that the ASIC 10 d is unable to supply electric charge to respective first electrode unit 210 d , this first electrode unit 210 d is in the turn-off state. When the second electrical switch 130 e is switched off such that the ASIC 10 d is unable to supply electric charge to respective second electrode unit 210 e , this second electrode unit 210 e is in the turn-off state. In the turn-off state, there is no electrical potential difference between the first fixed electrode 20 d and the first movable electrode 30 d or between the second fixed electrode 20 e and the second movable electrode 30 e.

The sensing capacitance of the first sensing component 11 d is adjusted when the working status of one of the first electrode units 210 d is controlled by corresponding one of the first electrical switches 130 d . More specifically, one of the first electrode units 210 d is in the turn-on state when the ASIC supplies electric charge to this first electrode unit 210 d through corresponding one of the first electrical switches 130 d . One of the first electrode units 210 d is in the turn-off state when the ASIC does not supply electric charge to this first electrode unit 210 d.

Moreover, the sensing capacitance of the second sensing component 11 e is adjusted when the working status of one the second electrode units 210 e is controlled by corresponding one of the second electrical switches 130 e . More specifically, one of the second electrode units 210 e is in the turn-on state when the ASIC supplies electric charge to this second electrode unit 210 e through corresponding one of the second electrical switches 130 e . One of the second electrode units 210 e is in the turn-off state when the ASIC does not supply electric charge to this second electrode unit 210 e.

In this embodiment, the first sensing component 11 d is configured to detect a first physical quantity, and the second sensing component 11 e is configured to detect a second physical quantity different from the first physical quantity. More specifically, the first sensing component 11 d is a barometer, and the second sensing component 11 e is an accelerometer.

As shown in FIG. 10 , the first electrical switches 130 d control respective first electrode units 210 d , such that the working status of some first electrode units 210 d is in the turn-on state, and the working status of the other first electrode units 210 d is in the turn-off state. When the atmospheric pressure around the MEMS apparatus with adjustable sensing capacitance 1 d is increased, the first movable portion 320 d is deformed, such that the distance between the first movable portion 320 d and the first electrode unit 210 d is changed. The variation of distance between the first movable portion 320 d and the first electrode unit 210 d generates a variation of electrical potential difference between the first fixed electrode 20 d and the first movable electrode 30 d.

Furthermore, the second electrical switches 130 e control respective second electrode units 210 e , such that the working status of some second electrode units 210 e is in the turn-on state, and the working status of the other second electrode units 210 e is in the turn-off state. When acceleration of a vehicle (such as car) equipped with the MEMS apparatus with adjustable sensing capacitance 1 d is change, the second movable portion 320 e moves toward to one of the second fixed portions 310 e so as to generate a variation of electrical potential difference between the second fixed electrode 20 e and the second movable electrode 30 e.

In this embodiment, an area A 1 of each first electrode unit 210 d is the same as an area A 2 of each second electrode unit 210 e . When the first sensing component 11 d and the second sensing component 11 e detect physical quantities at the same time, the number of the first electrode units 210 d in the turn-on state is N1, the number of the second electrode units 210 e in the turn-on state is N2, and the following condition should be satisfied: N1>N2. Therefore, when the first sensing component 11 d detects slight atmospheric pressure variation and the second sensing component 11 e detects an acceleration, the second sensing component 11 e is prevented from generating an overly high sensing capacitance, and thus the ASIC 10 d is prevented from breaking down. In another embodiment, when the first sensing component 11 d detects larger variation of first physical quantity and the second sensing component 11 e detects smaller variation of second physical quantity, it is proper that each first electrode unit 210 d and each second electrode unit 210 e has the same area, and the number (N1) of the first electrode units 210 d in the turn-on state is smaller than the number (N2) of the second electrode units 210 e in the turn-on state.

In another embodiment, when the first sensing component 11 d and the second sensing component 11 e work at the same time, a total area of the first electrode units 210 d in the turn-on state is TA1, a total area of the second electrode units 210 e in the turn-on state is TA2, and the following condition should be satisfied: TA1>TA2. Therefore, when the first sensing component 11 d detects slight atmospheric pressure variation and the second sensing component 11 e detects an acceleration, the second sensing component 11 e is prevented from generating an overly high sensing capacitance, and thus the ASIC 10 d is prevented from breaking down.

In still another embodiment, when the first sensing component 11 d detects larger variation of first physical quantity and the second sensing component 11 e detects smaller variation of second physical quantity, it is proper that the total area (TA1) of the first electrode units 210 d in the turn-on state is smaller than the total area (TA2) of the second electrode units 210 e in the turn-on state.

According to the present disclosure, the MEMS apparatus with adjustable sensing capacitance includes multiple electrical switches and multiple electrode units. The electrical switches are electrically coupled to respective electrode units, such that the working status of one electrode unit is controlled by corresponding one electrical switch. The sensing capacitance of the MEMS apparatus is able to be adjusted by independently controlling the working status of the electrode units. The MEMS apparatus with adjustable sensing capacitance is favorable for precisely detect the variation of physical quantity as well as prevent the ASIC from breaking down. When the MEMS apparatus is required to detect small variation of physical quantity, most of the electrode units is in the turn-on state (a working status when the electrode unit is supplied with electric charge). When the MEMS apparatus is required to detect large variation of physical quantity, few electrode units is in the turn-on state so as to prevent the readout circuit of the ASIC from malfunction.

The embodiments are chosen and described in order to best explain the principles of the present disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the present disclosure and various embodiments with various modifications as are suited to the particular use that is being contemplated. It is intended that the scope of the present disclosure is defined by the following claims and their equivalents.

1 , 1 a , 1 b , 1 c , 1 d MEMS apparatus with adjustable sensing capacitance

2 d substrate

21 top surface

10 , 10 d ASIC

110 top surface

120 , 120 d readout circuit

130 electrical switch

130 d first electrical switch

130 e second electrical switch

11 , 11 a , 11 b , 11 c sensing component

11 d first sensing component

11 e second sensing component

20 , 20 a , 20 c fixed electrode

20 d first electrode

20 e second electrode

210 electrode unit

210 a , 210 d first electrode unit

211 a first electrode finger

220 a , 210 e second electrode unit

221 a second electrode finger

210 c central electrode unit

220 c annular electrode unit

21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 electrode assembly

30 , 30 a , 30 b , 30 c movable electrode

30 d first movable electrode

30 e second movable electrode

310 , 310 a , 310 b , 310 c fixed portion

310 d first fixed portion

310 e second fixed portion

320 , 320 a , 320 b , 320 c movable portion

320 d first movable portion

320 e second movable portion

321 a third electrode finger

321 e movable mass block

322 e elastic component

330 a flexible portion