JP2009198337A - Sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor device capable of preventing its destructive withstand pressure from lowering, while enhancing the sensitivity. <P>SOLUTION: The sensor device 1 comprises a frame part 10, a movable part 20 and a carbon nanotube element 31 bridging across the frame part 10 and the movable part 20. Furthermore, the sensor device 1 comprises a corrugated part 40 which is made corrugated and connecting the frame part 10 to the movable part 20, and is configured to detect a physical quantity of an object to be detected by using the variation in the resistance value of the carbon nanotube element 31. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sensor device.

There is known a sensor device in which a thin film diaphragm is formed inside a frame portion and a carbon nanotube element is formed on the diaphragm. In this sensor device, the diaphragm is displaced according to the change in the quantity of material, and the carbon nanotube element is distorted. The resistance value of the carbon nanotube element changes due to this strain, and various physical quantities can be detected by the change in the resistance value (see Patent Document 1).
JP 2006-90807 A

  In the sensor device, in order to increase sensitivity, it is necessary to increase the amount of displacement of the diaphragm and increase the strain applied to the carbon nanotube element. For this reason, it is necessary to form a thinner diaphragm. However, in the conventional sensor device, if the diaphragm is thinned, the breakdown voltage of the diaphragm is lowered, so that there is a limit to increasing the sensitivity. In particular, in fields such as in-vehicle, there is a limit to making the diaphragm thinner in order to prevent the breakdown of the sensor function in order to avoid stopping the sensor function, making it more difficult to achieve high sensitivity. ing.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a sensor device capable of suppressing a decrease in breakdown voltage while achieving high sensitivity. It is.

  A sensor device according to the present invention includes a frame portion that is fixedly supported, a movable portion that is displaced according to a change in physical quantity, a carbon nanotube element that spans between the frame portion and the movable portion, a frame portion, and a movable portion. And a corrugated portion formed in a bellows shape, and detects a physical quantity to be detected based on the amount of change in the resistance value of the carbon nanotube element.

  According to this sensor device, the bellows-like corrugated portion that connects the frame portion and the movable portion is provided, so that the displacement of the movable portion relative to the frame portion can be increased by the expansion and contraction of the bellows, and the resistance of the carbon nanotube element is increased. The amount of change in value can also be increased. Therefore, in order to increase the amount of change in the resistance value of the carbon nanotube element, it is not necessary to excessively reduce the thickness of the movable part and the like, and a reduction in breakdown voltage can be suppressed while achieving high sensitivity.

  In the sensor device according to the present invention, it is preferable that a plurality of carbon nanotube elements are provided side by side from the frame part toward the movable part, and these carbon nanotube elements are electrically connected on the movable part.

  According to this sensor device, a plurality of carbon nanotube elements are provided side by side from the frame part toward the movable part, and since these carbon nanotube elements are electrically connected on the movable part, the displacement amount of the movable part It is not necessary to provide an electrode connected to the wiring pattern on the movable part in order to detect the above. For this reason, it is possible to perform wiring to a stable part called the frame part without wiring to a member to be displaced called the movable part, and disconnection or the like can be prevented.

  In the sensor device according to the present invention, the movable part is supported by the corrugated part on the frame part over the entire circumference, and the movable part and the corrugated part are formed into a thin film to form a diaphragm part, and the resistance value of the carbon nanotube element It is preferable to detect the pressure difference between the front and back of the diaphragm portion based on the amount of change.

  According to this sensor device, the movable part is supported by the frame part over the entire circumference by the corrugated part, and the movable part and the corrugated part are formed into a thin film to form a diaphragm part, and the amount of change in the resistance value of the carbon nanotube element Therefore, the sensor device according to the present invention can be used as a pressure sensor in order to detect the pressure difference between the front and back surfaces of the diaphragm portion.

  In the sensor device according to the present invention, it is preferable that the sensor device further includes a weight provided on the movable portion, and detects an acceleration applied to the weight based on a change amount of the resistance value of the carbon nanotube element.

  According to this sensor device, the sensor device according to the present invention is further provided with a weight provided in the movable part, and the sensor device according to the present invention detects the acceleration applied to the weight based on the change amount of the resistance value of the carbon nanotube element. It can be used as a sensor.

  In the sensor device according to the present invention, it is preferable that a plurality of carbon nanotube elements are provided in directions orthogonal to each other in a planar arrangement state.

  According to this sensor device, since a plurality of carbon nanotube elements are provided in a direction orthogonal to each other in the planar arrangement state, acceleration in a two-dimensional direction on the plane can be detected and acceleration in a direction perpendicular to the plane can be detected. can do. Therefore, an acceleration sensor that detects acceleration in a three-dimensional direction can be provided.

  According to the present invention, it is possible to suppress a decrease in breakdown voltage while achieving high sensitivity.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram illustrating a sensor device according to a first embodiment of the present invention, in which (a) is a cross-sectional view and (b) is a plan view. The sensor device 1 is formed by processing a silicon substrate and detects a physical quantity applied to the device. As shown in FIG. 1, the sensor device 1 includes a frame portion 10, a movable portion 20, a plurality of carbon nanotube portions 30, and a corrugated portion 40. In the first embodiment, a sensor device 1 that detects a pressure difference as a physical quantity to be detected will be described as an example.

  As shown in FIG. 1B, the frame portion 10 is formed in a rectangular frame shape, and is fixedly supported on, for example, a glass pedestal. The movable part 20 is displaced according to the physical quantity applied to the sensor device 1 and is formed in a thin film shape by forming a concave part from the back side by, for example, anisotropic etching (FIG. 1A). reference). As shown in FIG. 1B, the movable portion 20 is supported by the corrugated portion 40 over the entire circumference inside the frame portion 10.

  The carbon nanotube portion 30 is constituted by a carbon nanotube element 31. The carbon nanotube element 31 is an element whose conductivity, that is, a resistance value changes according to deformation, and is arranged so as to be bridged between the frame portion 10 and the movable portion 20. In addition, as shown in FIG. 1B, a plurality of carbon nanotube elements 31 (two in the present embodiment) are provided side by side from the frame portion 10 toward the movable portion 20, and each carbon nanotube element 31 is provided. An electrode 32 is provided at one end, and a contact portion 33 is provided at the other end. Specifically, the first carbon nanotube element 31 a is spanned from the first electrode 32 a on the frame portion 10 toward the movable portion 20, reaches the contact portion 33 on the movable portion 20, and is folded back at the contact portion 33. Thus, the second carbon nanotube element 31b is stretched over the frame portion 10 and reaches the second electrode 32b on the frame portion 10. As described above, the carbon nanotube elements 31 provided side by side have a structure of being electrically connected on the movable portion 20.

  In the present embodiment, the carbon nanotube portion 30 includes the contact portion 33, but the present invention is not limited thereto, and the contact portion 33 may not be included.

  In addition, a plurality of carbon nanotube portions 30 are provided, and the first carbon nanotube portion 30 a is bridged from one end side of the rectangular frame portion 10 toward the movable portion 20. Further, the second carbon nanotube portion 30 b is bridged from the other end side of the frame portion 10 toward the movable portion 20. As described above, the carbon nanotube part 30 is configured to be bridged from both sides of the frame part 10 to the movable part 20.

  The corrugated portion 40 connects the frame portion 10 and the movable portion 20 and is configured in a bellows shape. The corrugated portion 40 is formed as a thin film. For this reason, the movable part 20 and the corrugated part 40 constitute a diaphragm part, and the movable part 20 is configured to be displaced in the front and back direction of the diaphragm part according to the pressure difference between the front and back sides of the diaphragm part.

  Next, the operation of the sensor device 1 according to this embodiment will be described. First, as shown in FIG. 1A, it is assumed that a higher pressure is applied from the back side of the diaphragm portion than the front side. At this time, since the diaphragm portion is formed as a thin film, the movable portion 20 is displaced to the front side. As a result, the carbon nanotube element 31 of the carbon nanotube portion 30 is also deformed, and the resistance value of the carbon nanotube element 31 changes. Based on the amount of change in the resistance value, a pressure difference between the front and back of the diaphragm is detected.

  In particular, in the present embodiment, since the bellows-like corrugated portion 40 is provided between the frame portion 10 and the movable portion 20, the amount of displacement of the movable portion 20 is larger than that when the bellows-like corrugated portion 40 is not used. Thereby, the amount of deformation of the carbon nanotube element 31 also increases, and the amount of change in resistance value also increases. Therefore, the sensor device 1 has an increased sensitivity for detecting the pressure difference.

  For detection of the pressure difference, for example, the first electrode 32a and the second electrode 32b are connected to a wiring pattern and a predetermined voltage is applied. Thereby, when the movable part 20 is displaced and the resistance value of the carbon nanotube element 31 is changed, the current value is changed, and the pressure difference between the front and back of the diaphragm part can be detected.

  Further, in the present embodiment, a plurality of carbon nanotube elements 31 are provided side by side and these are electrically connected on the movable part 20, so that the electrodes connected to the wiring pattern in order to detect the displacement amount of the movable part 20 32 need not be provided on the movable part 20. For this reason, it is possible to perform wiring to a stable part called the frame part 10 without wiring to a member that is displaced such as the movable part 20, and disconnection or the like can be prevented.

  As described above, according to the sensor device 1 according to the first embodiment, the bellows-like corrugated portion 40 that connects the frame portion 10 and the movable portion 20 is provided. The amount of displacement of the carbon nanotube element 31 can also be increased. Therefore, in order to increase the amount of change in the resistance value of the carbon nanotube element 31, it is not necessary to make the movable portion 20 or the like too thin, and it is possible to suppress a decrease in breakdown voltage while achieving high sensitivity.

  Further, a plurality of carbon nanotube elements 31 are provided side by side from the frame part 10 toward the movable part 20, and since these carbon nanotube elements 31 are electrically connected on the movable part 20, the displacement of the movable part 20 There is no need to provide an electrode connected to the wiring pattern on the movable portion 20 in order to detect the amount. For this reason, it is possible to perform wiring to a stable part called the frame part 10 without wiring to a member that is displaced such as the movable part 20, and disconnection or the like can be prevented.

  The movable portion 20 is supported by the frame portion 10 over the entire circumference by the corrugated portion 40, and the movable portion 20 and the corrugated portion 40 are formed into a thin film to form a diaphragm portion, and the resistance value of the carbon nanotube element 31 is changed. Since the pressure difference between the front and back of the diaphragm portion is detected based on the amount, the sensor device 1 according to the present embodiment can be used as a pressure sensor.

  Next, a sensor device according to a second embodiment will be described. The sensor device according to the second embodiment is the same as that of the first embodiment, but the configuration is partially different. Hereinafter, only differences from the first embodiment will be described.

  FIG. 2 is a configuration diagram illustrating a sensor device according to the second embodiment, in which (a) is a cross-sectional view and (b) is a plan view. The sensor device 2 shown in FIG. 2 detects acceleration as a physical quantity to be detected, and includes a weight 50 as shown in FIG. 2A in addition to the configuration shown in FIG. . The weight 50 is provided integrally with the movable portion 20 so as to be positioned in a recess formed by etching.

  A plurality (four in this embodiment) of the carbon nanotube portions 30 are provided in a direction orthogonal to each other in a planar arrangement state. Specifically, as shown in FIG. 2B, assuming the Z axis in a direction orthogonal to the frame surface, and assuming the X axis and Y axis parallel to the frame surface and orthogonal to each other, the first and The second carbon nanotube portions 30a and 30b are arranged so as to be parallel to the X axis. The remaining two third and fourth carbon nanotubes 30c and 30d are arranged so as to be parallel to the Y axis. Thereby, the sensor apparatus 2 can function as a three-dimensional acceleration sensor.

  Next, the operation of the sensor device 2 according to this embodiment will be described. FIG. 3 is a cross-sectional view showing the operation of the sensor device 2 according to the second embodiment. First, it is assumed that acceleration is applied in a positive direction with respect to the X axis. In this case, the movable part 20 rotates about the gravity center position G of the weight 50. Therefore, the first carbon nanotube portion 30a is displaced in the negative direction with respect to the Z axis (the front side of the movable portion 20 is positive), and the second carbon nanotube portion 30b is in the positive direction with respect to the Z axis. Displace. As a result, the resistance value of the carbon nanotube elements 31 of the first and second carbon nanotube portions 30a and 30b changes. In this case, the third and fourth carbon nanotube portions 30c and 30d are twisted, and the resistance values of the carbon nanotube elements 31 of the third and fourth carbon nanotube portions 30c and 30d also change. Then, the acceleration applied to the weight 50 is detected from the change amount of the resistance value.

  On the other hand, it is assumed that acceleration is applied in a positive direction with respect to the Z axis. In this case, in the movable portion 20, the gravity center position G of the weight 50 is displaced in the positive direction with respect to the Z axis. At this time, the carbon nanotube elements 31 of the first to fourth carbon nanotube portions 30a to 30d are also displaced in the positive direction with respect to the Z axis, and the resistance value changes. Then, the acceleration applied to the weight 50 is detected from the change amount of the resistance value.

  FIG. 3A illustrates the case where acceleration is applied in the positive direction with respect to the X axis, but the case where acceleration is applied in the negative direction with respect to the X axis and the case where the acceleration is applied with respect to the Y axis. The same applies when acceleration is applied in a positive or negative direction. FIG. 3B illustrates the case where acceleration is applied in a positive direction with respect to the Z axis. However, the same applies to the case where acceleration is applied in a negative direction with respect to the Z axis. In addition, when acceleration is applied from a direction that does not follow the XYZ axes, the sensor device 2 combines the example shown in FIG. 3A and FIG. It is possible to detect the acceleration applied to.

  Thus, according to the sensor device 2 according to the second embodiment, as in the first embodiment, it is possible to suppress a decrease in the breakdown voltage while achieving high sensitivity.

  Further, according to the second embodiment, the weight 50 provided in the movable portion 20 is further provided, and the acceleration applied to the weight 50 is detected based on the change amount of the resistance value of the carbon nanotube element 31. The sensor device 2 according to the embodiment can be used as an acceleration sensor.

  In addition, since a plurality of carbon nanotube elements 31 are provided in directions orthogonal to each other in the planar arrangement state, acceleration in a two-dimensional direction can be detected on the plane, and acceleration in a direction perpendicular to the plane can be detected. . Therefore, an acceleration sensor that detects acceleration in a three-dimensional direction can be provided.

  The sensor device according to the present invention has been described above based on the embodiments. However, the present invention is not limited to this, and modifications may be made without departing from the spirit of the present invention.

  For example, although the carbon nanotube part 30 has the two carbon nanotube elements 31 in the said embodiment, it is not restricted to this, One or three or more may be sufficient.

  Moreover, in the said embodiment, although the carbon nanotube part 30 is two or four, not only this but one, three, or five or more may be sufficient.

  Furthermore, in the sensor device 2 according to the second embodiment, the corrugated unit 40 is provided over the entire circumference of the movable unit 20 and is supported by the frame unit 10. The corrugated part 40 does not have to be provided.

It is a block diagram which shows the sensor apparatus which concerns on 1st Embodiment of this invention, Comprising: (a) is sectional drawing, (b) is a top view. It is a block diagram which shows the sensor apparatus which concerns on 2nd Embodiment, Comprising: (a) is sectional drawing, (b) is a top view. It is sectional drawing which shows operation | movement of the sensor apparatus which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Sensor apparatus 10 Frame part 20 Movable part 30 Carbon nanotube part 31 Carbon nanotube element 40 Corrugated part 50 Weight

Claims (5)

A fixedly supported frame portion;
A movable part that is displaced according to a change in physical quantity;
A carbon nanotube element bridged between the frame part and the movable part;
A corrugated portion that connects the frame portion and the movable portion and is formed in a bellows shape;
A sensor device that detects a physical quantity to be detected based on a change amount of a resistance value of the carbon nanotube element. 2. The carbon nanotube elements are provided side by side from the frame part toward the movable part, and these carbon nanotube elements are electrically connected on the movable part. Sensor device. The movable part is supported by the frame part over the entire circumference by the corrugated part,
The movable part and the corrugated part are formed into a thin film to form a diaphragm part,
The sensor device according to claim 1, wherein a pressure difference between the front and back of the diaphragm portion is detected based on a change amount of a resistance value of the carbon nanotube element. A weight provided on the movable part;
The sensor device according to claim 1, wherein an acceleration applied to the weight is detected based on a change amount of a resistance value of the carbon nanotube element. The sensor device according to claim 4, wherein a plurality of the carbon nanotube elements are provided in directions orthogonal to each other in a planar arrangement state.

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