Key Engineering Materials Vols. 609-610

Abstract: This paper presents a novel approach to enhancing power-handling capability of metal-contact radio-frequency micro-electro-mechanical systems (RF MEMS) switches based on an Optimized Array Configured (OAC) contact dimples design. The simulation results reveal that this strategy can distribute the RF current more uniformly through each contact of the switch than traditional multiple parallel-configured contacts design, thus leading to a more effective reduction of current through each contact. Therefore, probability of micromelding and adhesion at metal contact point owing to localized high current induced Joule heating, which limits the power handling capability of the metal-contact RF MEMS switch, can be effectively reduced by the proposed approach. Comparing with previously fabricated switch, power-handling capability of the switch with OAC contact dimples can be dramatically improved over 390%.

Abstract: Microbial fuel cells (MFCs) are regarded as a promising and environmental friendly method for wastewater treatment and bio-production. The output power of a single cell is inadequate to drive loads directly. Microbial fuel cells stacked in serials will promote bio-production or bioremediation and the voltage of the MFCs can be scaled up by connecting the cells in serials, whereas voltage reversal may emerge in this case. The causes for reversing polarity of MFCs have received great attention in recent years. This paper designs a power management circuit for microbial fuel cell, studies the mechanisms of voltage reversal and the approaches to solve the problem.

Abstract: Traditional rectifier circuit can convert AC to DC, but some disadvantages cant be avoided, such as small output current, high power consumption, low conversion efficiency. This paper designs a new type of rectifier voltage-multiplier circuit named MR_MOS circuit. It uses a low let-through resistance MOS tube to replace the conventional rectifier diode, and adds the voltage-multiplying factor to the synchronous input port. Therefore, it can improve the rectifier effect and increase the output voltage. By the simulation result of Synopsys Saber Platform, it shows that the new type circuit can implement the rectification and voltage-multiplying by the simulating output pulse voltage of nanofiber made in Deakin University as the source of excitation. It can provide the basic theoretical of the piezoelectric energy harvester (PEH) development, and has certain reference significance to the development of piezoelectricity technology.

Abstract: In this work, the effect of wrinkled microstructures on surface wettbility of ginkgo leaf was investigated. The upper and lower layers of the ginkgo leaf were comparatively measured by Scanning Electron Microscopy (SEM) for contrast of morphological characters. Measurement results show that the upper epidermis is mainly composed of regularly long-rangle stripes of cellular structures with gently smooth cell wall. On the other hand, the lower one is made up of chaotically isolated cellular structures with wrinkled cell wall. The comparative measurement of contact angle (CA) and roll-off angle in the upper and lower epidermis with deionized water was conducted. Wetting behaviors indicate that the lower has stronger hydrophobicity and weaker adhesion than the upper. Through theoretical analysis, the difference in wettability and adhesion was the result of isolated micro-bumps made by hierarchical wrinkles on the lower epidermis, leading to form solid-air-liquid interface between water and wrinkled surface. This research explains the difference of ginkgo leaf in wettability, and has important reference value in the design and preparation of the surface for the biomimetic materials.

Abstract: The precise measurement and feature information extraction of the biological macroscopic body shapes and surface micro-morphologies is an important precondition to obtain configuration resources directly in research of functionality biomimetics. The sharks with low-resistance body shape and scarfskin were selected as the typical example of creatures simultaneously with functional body shape and surface micro-morphology. Taking a frozen Carcharhinus brachyurous body and a piece of pretreated scarfskin as the biological samples, the measurement and reconstruction of its macroscopic body shape and surface micro-morphology were conducted respectively. The experimental results indicate that the measuring and reconstructing methods adopted can efficiently ensure the facticity and integrity of the measurement results, which contributes to the structure digitalization and feature information extraction of the biological prototypes. The study demonstrated in this paper may provide method references on information collection and data processing for design of bionic functional devices and interfaces.

Abstract: Features analysis is an important task which can significantly affect the performance of automatic bacteria colony picking. This paper presents a novel approach for adaptive colony segmentation by classifying the detected peaks of intensity histograms of images. The relevance and importance of these features can be determined in an improved support vector machine classifier using unascertained least square estimation. Experimental results show that the proposed unascertained support vector machine (USVM) has better recognition accuracy than the other state of the art techniques, and its training process takes less time than most of the traditional approaches presented in this paper.

Abstract: To improve yield and quality of lettuce in hydroponic, the growth, quality and activities of enzymes in nitrogen metabolism of lettuce in hydroponics were studied with nanodevices. The results showed that the nitrate reductase activities (NRA) in plants with nanodevices were significantly higher than the control at 16rd day after transplanting (DAT). On the 25th DAT, the shoot fresh weight of lettuce treated with 5.6cm²/L nanodevices was 17.8% higher than the control, while there was no difference in dry weights of shoot among different treatments. The NRA of lettuce increased gradually with the amount of nanodevices increasing from 0 cm²/L to 5.6 cm²/L, then decreased with nanodevices amount increasing. There was no obvious difference in the activities of glutamate dehydrogenase (GDH) and glutamate synthase (GOGAT) among different treatments,while glutamine synthase (GS) activity was enhanced with the increasing of nanodevices amount. On the 34th DAT, the shoot fresh weight of lettuce treated by 5.6cm²/L nanodevices was 11.2% higher than the control. The activities of NR and GS treated by 11.2cm²/L increased 39.7%, 97.7%, respectively compared with CK, while the activities of GDH and GOGAT treated by 5.6cm²/L increased 89.0%, 77.3%, respectively. In treatment with 5.6 cm²/L nanodevices in nutrient solution, the contents of soluble protein, flavonoid, soluble phenolic and ascorbic acid (VC) in lettuce increased 92.8%, 19.8%, 36.7% and 61.5%, respectively.The nitrate content in lettuce significantly increased with the using of nanodevices, but did not exceed the national standard. In conclusion, the yield and quality of hydroponic lettuce were improved by nanodevices, and the activities of enzymes in nitrogen metabolism were enhanced, especially at 25th and 34th DAT and best dosage of nanodevices is 5.6 cm²/L.

Abstract: In this paper, a parylene-based three-dimensional cuff electrode for peripheral nerve stimulation was proposed and simulated. The three-dimensional (3D) finite element model was built for simulation study of the electrode. The simulation results show this design has higher power efficiency than conventional planar electrode and it can realize selective stimulation of different fascicles in the target nerve. Moreover, the tripolar configuration has better control of the stimulation electric field than monopolar.

Abstract: In clinic practice, a strong appeal for painless transdermal injection is pursued, especially for patient drug delivery that cannot be administered orally. A new disposable painless syringe with MEMS technology is presented. The mode of micro needle array and a flexible PDMS container of hemisphere shape are given, and the behavior of the drug liquid flow through the needles is described based on port ontology to model miniature syringe and explains the phenomena of clog formation. The analysis and formulas have theoretically been derived, and the performances and the clog phenomena have been simulated. Therefore, micro needles inserted into the human skin can realize painless injection based on port ontology modeling.

Abstract: The growing and evolving dynamics in mass and force measurements has inevitably necessitated the need for high precision and accurate results. As a result, measurements in micro-gram (s) and nanoNewtons levels have increasingly attracted potential research interests. In an effort to develop such solutions, the National Institute of Metrology (NIM) has set up a new robot system CCR10 (readability 0.1μg) for accurate measurements of weight (s) ( 1 mg). This system is based on computer controls and linear-drive trains, and is used for calibration/verification of weight (s) below 10 g. A detailed description of the robots metrological parameters and calibration results thereof is presented in the current paper. Keywords: Micro Weights; nanoForce; Automatic Mass Comparator; Robot System; Calibration