CN102607545A - Micro-machinery gyroscope based on field emission of carbon nano tube array - Google Patents

Abstract

The invention provides a micro-machinery gyroscope based on field emission of a carbon nano tube array, relating to the gyroscope. The invention provides the micro-machinery gyroscope based on the field emission of the carbon nano tube array, which has the advantages of strong robustness and high stability and flexibility. The micro-machinery gyroscope is provided with an upper base and a lower base, wherein the upper base and the lower base are bonded through silicon-silicon and are connected with a peripheral driving and detecting circuit through a metal lead wire; the upper base is provided with a base, a driving elastic beam, a detection elastic beam, a mass block and a driving comb tooth; the upper base is used as an anode; a carbon nano tube uniform array which is vertically directed grows on the lower base; and the carbon nano tube uniform array which is vertically directed is used as a cathode.

Description

Micro-mechanical gyroscope based on the emission of carbon nano pipe array field

Technical field

The present invention relates to a kind of gyroscope, especially relate to a kind of micro-mechanical gyroscope based on the emission of carbon nano pipe array field.

Background technology

Gyroscope is the sensor that is used for measured angular speed or angular displacement.According to principle of work, gyroscope can be divided into Ge Shi (Coriolis) gyroscope, magnetic suspension rotor gyroscope, Sagnac (Sagnac) gyroscope, magnetic resonance gyroscope appearance etc.There are problems such as too big, the portable difference of volume and sensitivity is low in early stage traditional gyroscope.In 30 years, have benefited from the fast development of MEMS (MEMS) technology in the past, the structural design of micro-mechanical gyroscope, manufacture craft, follow-up signal treatment circuit and responsive displacement conversion mechanism etc. have all obtained considerable progress.Micro-mechanical gyroscope has advantages such as volume is little, cost is low, low in energy consumption, and the micro-mechanical gyroscope of different structure has different precision, and the gyroscope of different accuracy is used in different applications.The gyroscope of the speed level of low precision is mainly used in auto industry and consumer electronics sector.At automotive field, micro-mechanical gyroscope is used for anti-rollover, anti-skidding control and electronic stability control etc.In the electric consumers field, micro-mechanical gyroscope can be used for carrying out inertia mouse and the Navigation Control etc. of Stability Control, the portable type electronic product of Stability Control, the game machine helmet of anti-shake control, the mobile phone of video camera.In addition, it can also be used for the attitude control system of robot.In military field, guided missile navigation, Aero-Space, platform stable, GPS etc. must be used high-precision micro-mechanical gyroscope.Atomic gyroscope has the highest precision in theory, but also just is in the laboratory experiment stage at present, does not also have real industrialization commodity to come out.Two kinds of the highest gyroscopes of business-like in the market precision are respectively fibre optic gyroscope and electrostatic gyro, still since bulky with cost an arm and a leg, these two types high-precision gyrostatic applications have received great restriction.Continuous expansion along with to high-performance gyroscope demand has obtained breakthrough based on the gyroscope of new principle and new material.Wherein, the field emission characteristics that utilizes the even carbon nanotube array is expected to develop novel highly sensitive micro-mechanical gyroscope to the sensitivity of change in displacement.

CNT since coming to light in 1991, and this accurate one dimension novel nano C material is with its excellent electricity and thermal property and receive much concern.Because the length-diameter ratio of CNT is very big and the tip curvature radius is very little; It is compared with product emission cathode materials such as traditional molybdenum, tungsten, silicon, adamass; Have higher physical strength, stable chemical properties more; Therefore CNT is a kind of extremely desirable field emitting electronic source, and its launch stability is better than metal.CNT just can be launched a large amount of electronics under relatively low voltage, the point discharge characteristic is very good; Can grow the even carbon nanotube array of vertical orientation at substrate surface through pecvd process, so emission is big, maximum current can reach 10mA/cm ²The field emission characteristic of excellence such as utilize the forward voltage of CNT low, current density is big, chemical property is stable can be processed highly sensitive minisize gyroscopes, accelerometer or pressure transducer etc.Present stage, the research of the field being launched microsensor also only is to be in the breadboard analog simulation stage, is primarily aimed at structure optimization, Vacuum Package, bonding technology etc. and studies.Bibliographical information is not also seen in the research of switching mechanism that the field emission characteristic of CNT is applied to the responsive displacement of gyroscope.

The theoretical ultimate principle of field emission is; The highfield that the voltage that is loaded between negative electrode and the anode produces makes the potential barrier of cathode surface reduce or attenuate; Thereby the generation tunnel effect, excitation electron emits from the negative electrode solid surface, and the current density of its emission satisfies:

$J=1.54\×{10}^{-6}\frac{{(\mathrm{\β}\·E)}^2}{\mathrm{\φ}}\exp (-6.87\×{10}^{-7}\frac{{\mathrm{\φ}}^{\frac{3}{2}}}{\mathrm{\β}\·E})|$

Wherein, J is a current density, and

is electric field intensity, and U is an impressed voltage; D is the distance between negative electrode and the anode; φ is the material surface work function, and β is the geometric factor of negative electrode, and β E is the most advanced and sophisticated electric field of negative electrode.Hence one can see that, and when other factors all remained unchanged, current density, J was along with the spacing d between negative electrode and the anode changes, and it can be used as the micro-displacement sensitive mechanism.

Chinese patent CN102042830A discloses a kind of silicon micromechanical gyroscope, comprises no Drive Structure silicon micromechanical gyroscope, with the drive motor of no Drive Structure silicon micromechanical gyroscope coupling.In addition, can also comprise slip ring; No Drive Structure silicon micromechanical gyroscope is connected to slip ring; Drive motor is connected through web member with slip ring.The disclosure drives the spin angle speed that provides through loading motor on no Drive Structure gyro, produce gyroscopic effect, comes the various attitude informations of responsive non-rotating carrier and rotating carrier.Through selecting for use miniature flat electric machine, miniature slip ring and angular contact ball bearing and web members such as flexible sheet shaft coupling and gyroaxis to being connected; The raising signal to noise ratio (S/N ratio) of adopting an effective measure has simultaneously reduced vibration noise that motor-driven brings to extracting the influence of useful signal.

Summary of the invention

The object of the present invention is to provide a kind of strong robustness, stability and highly sensitive micro-mechanical gyroscope based on the emission of carbon nano pipe array field.

The present invention is provided with substrate and following substrate, and the two lumps together through silicon-silicon bond and links to each other with peripheral driver and testing circuit through metal lead wire with following substrate in said upward substrate; Said going up in the substrate is manufactured with pedestal, driving elastic beams, detection elastic beam, mass and driving comb, and said upward substrate is as anode; The directed even carbon nanotube array of growth of vertical in the said substrate down, the even carbon nanotube array of said vertical orientation is as negative electrode.

Said upward substrate can be adopted substrate on the silicon, and said substrate down can be adopted substrate under the silicon.

Said mass can be made up of inner frame and outside framework.

The driving voltage that is applied on the driving comb electrode is to constitute push-pull type by DC voltage stack alternating voltage to drive; Mass is to do the constant amplitude simple harmonic oscillation on the Y direction at driving direction; At this moment; If total system is experienced when the input angular velocity of X axle,, therefore changed the transmitting range of CNT field emission because the coriolis force that Coriolis effect produces makes mass produce displacement in the Z direction; The field transmitter current also changes thereupon, can obtain the size of input angular velocity through the measurement field transmitter current.

The present invention with the various superior performance of this new material of CNT particularly field emission performance be applied to gyroscope arrangement; Thereby new material and new responsive displacement conversion mechanism in gyroscope arrangement, have been introduced; The stray capacitance that the stable field emission characteristic of CNT can overcome the capacitive displacement conversion regime is big, the output signal is weak, be subject to shortcomings such as electrode size and structure influence; Strong, the shortcomings such as tunnel current is extremely faint, tunnel current control system complicacy of the 1/f tunnel sensing noise that also can overcome tunnel type displacement conversion mechanism are expected to make that reliability, robustness and the sensitivity of gyroscope are improved.

The present invention is according to the gyrostatic operating characteristic of micromechanics Coriolis effect; Introduce the new material of even carbon nanotube array as detecting electrode; The stable field emission performance that utilizes CNT as mass the detection side to the micro-displacement switching mechanism; Thereby measure Corioli's acceleration according to the size of field transmitter current and record the input angular velocity of rotation, promote novel MEMS gyroscope to high stability and high precision development.

This shows that the present invention has following advantage:

1) sensitivity and robustness improve greatly.The length of driving elastic beams and width are respectively 400 μ m and 5 μ m; The length and the width that detect elastic beam are respectively 80 μ m and 20 μ m; When the thickness of device movable structure was 30 μ m, it was more approaching with the natural frequency that detects mode to drive mode, system highly sensitive.The length of CNT is 40～50 μ m, and the spacing between negative electrode and the anode is 100 μ m, and when loading the voltage of 300V between negative electrode and the anode, a transmitter current is at 2.5～5 μ A, and a transmitter current is big.The field transmitter current character of even carbon nanotube array does not receive the influence of factors such as device size fluctuation, strong robustness.

2) reduce driving direction to the detection side to coupling, avoid the influence of the transverse movement displacement of mass to the CNT field emission performance, improve measuring stability.Mass is made up of inner frame and outside framework; The driving movable broach is made on the inner frame; Inner frame links to each other with outside framework through four driving elastic beams; So it is very little to the coupling that detects mode to drive mode, overcome the transversal displacement effect to the detection side to the error that produces of autoelectronic current.

3) quality factor of device is high.In order to guarantee the field emission characteristics of CNT, device must Vacuum Package, and vacuum tightness is 7 * 10 ^-7Pa, and except field emission characteristics, CNT also has very strong gas absorption ability, can adsorb gas remaining in the cavity, improves the quality factor of device.

Description of drawings

Fig. 1 is the structural representation of the embodiment of the invention.

Fig. 2 is the vertical view of Fig. 1.

Fig. 3 is the side view of Fig. 1.

In Fig. 1～3, respectively be labeled as: 1a, 1b are the pedestal of last substrate, and 2 is the inner frame of mass; 3 is the outside framework of mass; 4a, 4b, 4c, 4d are for detecting elastic beam, and 5a, 5b, 5c, 5d are driving elastic beams, and 6a, 6b are driving comb; 7 are substrate down, and 8 are CNT (uniform array of the vertical orientation of in following substrate, growing).

Embodiment

Following examples will combine Fig. 1～3 couple the present invention to do further description.

The present invention is by the pedestal 1 of last substrate; The inner frame 2 of mass; Detection elastic beam 4a, 4b, 4c, the 4d of 3,4 symmetries of outside framework of mass, the driving elastic beams 5a of 4 symmetries, 5b, 5c, 5d; 72 couples of driving comb 6a, the 6b of front and back symmetry, the even carbon nanotube array 8 of following substrate 7 and vertical orientation is formed.Two framed structures that mass is made up of inner frame 2 and outside framework 3, inner frame 2 links to each other with outside framework 3 through driving elastic beams 5a, 5b, 5c, 5d, and outside framework 3 links to each other with pedestal 1 through detection elastic beam 4a, 4b, 4c, 4d.Grown in the following substrate 7 even carbon nanotube array 8 of vertical orientation.Substrate is closed technology through silicon-silicon bond and is bonded together an anode and the negative electrode launched as the field respectively up and down.

Below provide the main reference size of embodiment.Mass is made up of inner frame and outside framework, the length of inner frame and wide 1320 μ m and the 420 μ m of being respectively; Outside framework inner length and width are respectively 1420 μ m and 1200 μ m, and frame width is 100 μ m; Long and wide 400 μ m and the 5 μ m of being respectively of driving elastic beams; The length and the wide 80 μ m and the 20 μ m of being respectively of responsive elastic beam; Driving comb width and spacing are respectively 5 μ m and 4 μ m; The thickness of movable structure is 30 μ m; Primary clearance between negative electrode and the anode is 100 μ m, loads the voltage of 300V between negative electrode and the anode.

Claims (3)

1. based on the micro-mechanical gyroscope of carbon nano pipe array field emission, it is characterized in that being provided with substrate and following substrate, the two lumps together through silicon-silicon bond and links to each other with peripheral driver and testing circuit through metal lead wire with following substrate in said upward substrate; Said going up in the substrate is manufactured with pedestal, driving elastic beams, detection elastic beam, mass and driving comb, and said upward substrate is as anode; The directed even carbon nanotube array of growth of vertical in the said substrate down, the even carbon nanotube array of said vertical orientation is as negative electrode.

2. the micro-mechanical gyroscope based on the emission of carbon nano pipe array field as claimed in claim 1 is characterized in that the said substrate on the substrate employing silicon of going up, and substrate under the silicon is adopted in said substrate down.

3. the micro-mechanical gyroscope based on carbon nano pipe array field emission as claimed in claim 1 is characterized in that said mass is made up of inner frame and outside framework.

Images