Despite significant efforts to develop micropumps, cumbersome driving equipment means that the design of portable micropumps remains a challenge. This study presents a stand-alone micropump system, which includes a peristaltic micropump based on piezoelectric actuation and a driving circuit. This battery-based driving circuit comprises a 12 V battery, an ATmega 8535 microprocessor, a 12 V-to-180 V DC to DC converter using transformerless technology, three differential amplifiers, an IC 7805, a phase controller, an A/D converter, a keyboard and an LCD module. The system can produce step-function signals with voltages of up to 228 V(pp) and frequencies ranging from 10 Hz to 100 kHz, as the inputs for the pump. It is portable and programmable with the package size of 22 x 12.8 x 9 cm. Additionally, this proposed system is used to design the driving signals of the pump which are 3-, 4, and 6-phase actuation sequences. This work performs the circuit testing and fluid pumping, and demonstrates the effects of actuation sequences on pump performance in terms of the dynamic behavior of the diaphragm, flow rates, back pressure and power consumption of the system. The experimental results show that the pump excited by the 6-phase sequence results in better performance compared with the 3- and 4-phase sequences, and produces a maximum flow rate of 36.8 microl/min and a maximum back pressure of 520 Pa with deionized water at 100 V (pp) and 700 Hz.

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This paper presents a bulk micromachining process to fabricate micro-constrained layer treatments (MCLT) on a microstructure to increase its damping, and demonstrates the damping improvement through calibrated experiments. MCLT consists of a silicon base structure (e.g., beams or plates), a viscoelastic photoresist layer, and an aluminum constraining layer. Silicon base beams and plates are fabricated from {100} wafer through Ethylene-Diamine-Pyrocatechol etch and buffered oxide etch. A 4.5-μm thick photoresist AZ4620 is spun on the silicon base beam as the viscoelastic layer. Finally, an aluminum layer is deposited through low-pressure vapor deposition as the constraining layer. To evaluate damping performance of MCLT, silicon beams with and without MCLT are subjected to swept-sine excitations by PZT from 0 to 100 kHz. In addition, a laser Doppler vibrometer and a spectrum analyzer measured frequency response functions (FRF) of the specimen. A finite element analysis identifies the resonance modes measured in FRF. Experimental results confirm that MCLT can increase damping of silicon beams by at least 40%. Significantly better damping performance is expected, if the loss factor of the viscoelastic layer is increased.

The purpose of this paper is to demonstrate the feasibility of active vibration control for meso- and microstrucutres through use of PZT (Lead-Zirconium-Titanium Oxide) thick films. This paper consists of two parts. The first part is to develop a sol-gel process to fabricate crack-free PZT thick films with thickness of 2 microns and area of 4 mm × 4 mm. The PZT thick film has a Pt/Ti bottom electrode and a gold top electrode. Moreover, the PZT thick film is fabricated on a silicon cantilever, whose dimensions are 20 mm × 15 mm × 0.4 mm. The second part is an experimental demonstration of active vibration control using the PZT thick film. In the experiment, a tiny bulk PZT patch is first glued to the silicon cantilever. A function generator drives the bulk PZT simulating a source of disturbance exciting the silicon cantilever. In the meantime, a laser Doppler vibrometer (LDV) measures velocity of the cantilever tip. With a phase shifter as the controller, the LDV measurement is fed back to the PZT thick-film actuator to actively control the cantilever vibration. To evaluate the effectiveness of the active vibration control, a spectrum analyzer measures the frequency response functions (FRF) from the bulk PZT voltage to the LDV response. Experimental results show that the simple active vibration control scheme can reduce resonance amplitude of the first bending mode by 66%.

By studying the formation of snowflakes, scientists have found that frequency data can be stored in water. Using the homeopathic principles of dilution and succussion, this study explored the relationship between aqueous information transmission and differences in the formation of water crystals. We utilized three different types of experimental solution: bali water, distilled water, and ionized water, and studied the water crystals sprouting from the resulting ice crystals. From the four significant phases of morphological change (mother tincture, 1X, 4c, and 30c), it was determined that at higher dilution ratios, crystals grown in either distilled or ionized water developed from crystallites into a single-body structure, approaching the higher energy form of straight edge hexagonals. This phenomenon demonstrates the features of coherent domains and water clusters, both of which match the homeopathic principles of energy waves and information transmission.