A novel computer security authentication system is proposed to improve computer security. There are two main differences between the novel system and the conventional one. First, the key is a physical code that is stored in counter meshing gears (CMEs). Second, the user's password is discriminated by a microelectromechanical systems (MEMS) coded lock. This system is composed of a MEMS coded lock, a peripheral component interconnect (PCI) card with a printed circuit board (PCB), and software in a basic input/output system (BIOS) chip. Unlike the old MEMS coded lock, two reset micromotors and an optoelectronic coupler are installed in the new MEMS coded lock. The circuit of the PCI card with PCB, which is used to drive the four micromotors of the lock, is developed. The software is assembled by netwide assembler (NASM) and written into the BIOS chip. Testing of the prototype shows that the MEMS coded lock can discriminate the user's password effectively. If the user's password is matched with the physical code, permission to use the computer is granted; otherwise, it is locked up.
The MEMS security stronglink with multi-try function has been fabricated for some specified information fields. The
structure, code and solidification are introduced. The stronglink consists of two groups of metal counter-meshing gears,
two pawl/ratchet mechanisms, and two driving micromotors and two resetting micromotors, which could make the
counter-meshing gears withdraw by raising the pawls. The counter-meshing gears are designed and solidified with the
operating logic of code mechanism. It is fabricated using the UV-LiGA process and precision mechanical technique.
This paper presents a parallel dynamic passive valveless micropump, which consists of three layers-valve, diaphragm and electromagnetic coil. The valve is wetly etched in a silicon wafer, the diaphragm is a PDMS (polydimethyl siloxane) film spun on a silicon wafer with embedded permanent magnet posts, and the coil is electroplated on a silicon substrate. Under the actuation of the magnetic field of the coil, the flexible diaphragm can be displaced upwards and downwards. After analyzing magnetic and mechanical characteristic of the flexible membrane and direction-dependence of the diffuser, this paper designed a micropump. And the relative length (L/d) of the micropump’s diffuser is 4.An 7×7 array of permanent magnetic posts is embedded in the PDMS film. Two diaphragms work in an anti-step mode, which can relieve the liquid shock and increase the discharge of the micropump. ANSYS® and Matlab® are adopted to analyze the actuation effect of the coil and the flow characteristic of the micropump. Results show that when actuated under a 0.3A, 100Hz current ,the displacement of the diaphragm is more than 30μm, and the discharge of the micropump is about 6μL/s.
The prevailing micromachined vibratory gyroscope typically has a proof mass connected to the substrate by a mechanical suspension system, which makes it face a tough challenge to achieve tactical or inertial grade performance levels. With a levitated rotor as the proof mass, a micromachined rotational gyroscope will potentially have higher performance than vibratory gyroscope. Besides working as a moment rebalance dual-axis gyroscope, the micromachined rotational gyroscope based on a levitated rotor can simultaneously work as a force balance tri-axis accelerometer. Micromachined rotational gyroscope based on an electrostatically levitated silicon micromachined rotor has been notably developed. In this paper, factors in designing a rotational gyro/accelerometer based on an electrostatically levitated disc-like rotor, including gyroscopic action of micro rotor, methods of stable levitation, micro displacement detection and control, rotation drive and speed control, vacuum packaging and microfabrication, are comprehensively considered. Hence a design of rotational gyro/accelerometer with an electroforming nickel rotor employing low cost UV-LIGA technology is presented. In this design, a wheel-like flat rotor is proposed and its basic dimensions, diameter and thickness, are estimated according to the required loading capability. Finally, its micromachining methods based on UV-LIGA technology and assembly technology are discussed.
The micromachined gyroscope has the characteristics of small volume, small mass and low cost, but the high resolution can not be obtained in ordinary micromachined gyroscope, which restricts the further popularization of micromachined gyroscope. The micromachined gyroscope of electromagnetic levitated rotor (MGELR) has the working principle of conventional mechanical gyroscope and the suitability to mass-produce through micromachined technique. The micromachined gyroscope with high sensitivity is hopeful to be obtained through this way. In order to decrease the electromagnetic field coupling between different coils, the micromachined gyroscope of electromagnetic levitated rotor with new structure is brought forward in the paper. Controlling circuit is simplified in the new structure. In the paper, the working mechanism of this micromachined gyroscope is analyzed on the basis of electromagnetic field theory. Using the finite element analysis software, ANSYS5.6, the feasibility of new structure is proved. The influence of levitating coil width and its inner diameter on levitating force is concluded in the paper, and the optimum values are obtained. In the paper two types of stability coils, fork coil and arc coil, are compared, and the conclusion that the arc coil is good to the stable levitation of micro-rotor is obtained. Above all, the optimum design of levitating coil and stability coil of micromachined gyroscope of electromagnetic levitated rotor is carried out in the paper, and these provide principle for fabrication ofthis micromachined gyroscope.
Dynamic passive valve micropump is a kind of PZT actuation, valveless micropump which has higher working frequency, high reliability, simple structure, low cost. It can easily match many kinds of requirement in application. Some micropumps have been fabricated in our laboratory. The performance of dynamic passive valve micropump is in close relationship with structural parameters such as diffuser's aperture angle, diffuser's channel length, diffuser's channel smallest cross-section diameter. At the same time, its performance also depends on the fluid' s Reynolds number and the working frequency of PZT actuation as well. In this paper, firstly we give the relationship between the performance of the micropump and these parameters. Then we build a micro hydrodynamic model of micro pump by the finite element method. In this model, we take the coupling of fluid in micro chamber and two micro valves into consideration. The restriction of micro fabrication is also considered. By simulation and computation, we obtained the fluid status such as laminar flow, turbulent flow. We also get the fluid motion status such velocity of flow, the direction of the current. By some calculation, we gain the flux of micropump. Based on these results, one optimization design of micropump is attained. And according to this design, we fabricated and assembled some samples of dynamic passive micropump.
The LIGA type process, utilizing SU-8 photoresist as alternative LIGA technology, can fabricate high aspect ratio microstructures without employing synchrotron light and suitable X-ray mask. Based on LIGA type process in this paper, detailed investigations of the modeling and fabrication of micro 3K-2 type planetary gear reducer, such as the modeling and design of micro reducer, CAD of micro gear mask, SU-8 UV photolithography, micro electroforming, micro molding, have been performed. And 400 um thickness sun gear, 400 um thickness planet gear, 200 um thickness fixed inner gear, and 200 um thickness rotary inner gear, whose teeth are 15,11,36,39 respectively, have been obtained. Utilizing these gears, the micro reducer whose modulus, outer diameter and velocity ratio are 0.03, 2mm, 44.2:1, has been assembled and applied in (phi) 2mm micro electro magnetic motor successfully.
An investigation that the diffraction efficiency of dichromated gelatin (DCG) holograms is stable in the high humidity (RH equals 85%) environment is reported. In this study, the amino group, one strong absorbing humidity groups of gelatin in DCG, is modified with acetic anhydride and changed into weak absorbing humidity groups, amide groups. The procedures of the molecule enclosure did not obviously affect the diffraction efficient of DCG holograms.
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