Jinyuan Yao

Anti-icing property of superhydrophobic octadecyltrichlorosilane film and its ice adhesion strength

An octadecyltrichlorosilane (OTS) superhydrophobic film using phase-separation method was prepared to demonstrate the antiicing property of superhydrophobic surfaces. The superhydrophobicity of the film at -5°C was investigated. It was found that the prepared OTS film retained its superhydrophobicity at -5°C by the measurement of contact angle and roll-off angle. The icing progress of water droplets on the surface at -15°C was observed. It showed that the prepared OTS film can markedly retard the icing process of water droplets and dramatically decrease the ice adhesion strength compared with that of blank surface, which can be used as anti-icing surfaces.

PREPARING Ni–W ALLOY FILMS WITH LOW INTERNAL STRESS AND HIGH HARDNESS BY HEAT TREATING

In this paper, the internal stress and hardness of Ni–W alloy films with W contents in the range of 0–59 wt% were investigated. The amorphous Ni–W alloy films were electrodeposited with 59 wt% W content and the structure of crystalline alloy films was formed after heat treating. The experimental results showed that heat treating could prepare Ni–W alloy films with lower internal stress compared with low W content alloy films, and the heat treated alloy films still have high hardness. The internal stress and the hardness were about 230 MPa and 1000 Hv, respectively, when the heat treating temperature was 550°C. The relation of internal stress and hardness with the structure of alloy films is discussed.

Shock-Resistibility of MEMS-Based Inertial Microswitch under Reverse Directional Ultra-High g Acceleration for IoT Applications

This paper presents a novel MEMS-based inertial microswitch design with multi-directional compact constraint structures for improving the shock-resistibility. Its shock-resistibility in the reverse-sensitive direction to ultra-high g acceleration (~hunderds of thousands) is simulated and analyzed. The dynamic response process indicates that in the designed inertial microswitch the proof mass weight G, the whole system’s stiffness k and the gap x2 between the proof mass and reverse constraint blocks have significant effect on the shock-resistibility. The MEMS inertial microswitch micro-fabricated by surface micromachining has been evaluated using the drop hammer test. The maximum allowable reverse acceleration, which does not cause the spurious trigger, is defined as the reverse acceleration threshold (athr). Test results show that athr increases with the decrease of the gap x2, and the proposed microswitch tends to have a better shock-resistibility under smaller gap. The measured responses of the microswitches with and without constraint structure indicates that the device without constraint structure is prone to spurious trigger, while the designed constraint structures can effectively improve the shock-resistibility. In this paper, the method for improving the shock-resistibility and reducing the spurious trigger has been discussed.

Fabrication of microcoil with large tilt-angle on polymer tube for electromagnetically-driven scanner in single fiber endoscope

This paper presents a novel scanner design for single fiber endoscope based on electromagnetically-driven microcoil with large tilt-angle, which can realize larger scanning scale utilizing the high-order resonance modal. As the important driven component, the microcoil with large tilt-angle on the polymer tube with 1mm diameter has been fabricated by our developed spray coating and cylindrical projection UV-lithography system [1], The modals and dynamic response of the designed scanner under high-order vibration have been simulated and analyzed. And the microcoil with 60° tilt-angle has been successfully fabricated on the polymer tube by wet etching and maskless electroplating process. Finally, the electromagnetic property and the maximum driven displacement of fabricated scanner have been evaluated, which is in agreement with that simulated ones.

Fabrication of electromagnetically-driven tilted microcoil on polyimide capillary surface for potential single-fiber endoscope scanner application

The design and fabrication of a Micro-electromechanical Systems (MEMS)-based tilted microcoil on a polyimide capillary are reported in this paper, proposed for an electromagnetically-driven single-fiber endoscope scanner application. The parameters of the tilted microcoil were optimized by simulation. It is proved that the largest driving force could be achieved when the tilt-angle, the pitch and the coil turns of the designed microcoil were 60°, 80 µm and 20, respectively. The modal simulation of the designed fiber scanner was carried out. The prototypes of the tilted microcoils were fabricated on the surface of polyimide capillary with 1 mm-diameter using our developed cylindrical projection lithography system. The dimensions of the two tilted microcoils were as follows: one was tilt-angle 45°, line width 10 ± 0.2 µm, coil pitch 78.5 ± 0.5 µm, and the other was tilt-angle 60°, line width 10 ± 0.2 µm, coil pitch 81.5 ± 0.5 µm. Finally, a direct mask-less electroplating process was employed to fabricate the copper microcoil with 15 µm thickness on the gold (Au) seed-layer, and the corresponding line width was expanded to 40 µm.

A novel inertial microswitch with synchronous follow-up compliant electrodes for extending output switch-on pulse width

This paper reports a novel inertial microswitch with synchronous follow-up compliant electrodes for extending output switch-on pulse width. The flexible movable electrode and stationary electrode are proposed to keep a continuous duration contact by double-stair and spring-shape structures, which can not only extend the output switch-on pulse width but also reduce the impact bounces. Then the inertial microswitch has been fabricated using surface micromachining and multilayer electroplating technology. The comparison testing results show that there is no contact bouncing behavior can be observed under ∼466g half sine-wave shock acceleration and the test output switch-on pulse width can reach 390μs, which is longer than that in the traditional design.

A MEMS inertial switch with compact constraint structures for lowering off-axis sensitivity

This paper proposes two novel laterally-driven inertial switches with multi-directional constraint structures for lowering off-axis sensitivity. First one is the inertial switch with one layer of serpentine springs. The second is the inertial switch with two layers of serpentine springs. ANSYS software was used to simulate the dynamic contact process of inertial switch, and the simulation results reveal that the design of symmetrical distribution of double layers serpentine springs plays an important role in resisting small acceleration disturbance from off-axis sensitive z-direction, and the constraint structures can resist large acceleration disturbance. The fabricated inertial switch by surface micromachining technology has been evaluated using a drop hammer system. The test results show that the symmetrical distribution of double layers serpentine springs reduce the displacement of proof mass in the off-axis sensitive direction under a small acceleration disturbance. Therefore, The combined efforts of double layers suspended springs and constraint structures effectively lower the off-axis sensitivity of the MEMS inertial switch.

Fabrication of spinneret for spinning non-circular microfiber based on UV-LIGA technique

A new method for manufacturing of arbitray cross section spinnerets. Application of UV-LIGA technique to fabricate the spinneret capillarys have been preliminarily discussed. Spinneret plate were deposited by electrotyping method firstly, then bond it with the outer frame using laser welding, the entire forming of spinneret is realized. The results show that the method not only can fabricate spinnerets with smooth surface and arbitray cross sections, but also have many advantages including high uniformity, high productivity and low cost.

Pd/Ni bilayer electrochemical microactuator

The hydrogen actuating microactuator works in the caustic electrolyte, the chemical stability of the materials is very important for the lifetime of this kind of microactuators,. As compared with mischmetal (Mm) based LaNi5 series alloy films reported before, palladium layers is more suitable for this purpose, In this paper, a prototype of electrochemical microactuator with Pd/Ni bilayer based on the hydrogen induced actuation is presented, the performance and microfabrication process of this microactuator are described in detail.