[Show abstract][Hide abstract] ABSTRACT: To prepare the gold nanoparticles (AuNPs) with uniform sizes, fine morphology, and good monodispersity, a pulsed mixing microfluidic system based on PZT actuation was presented. The system includes PZT micropump and Y type micromixer. By adjusting voltage (entrance flow rate), pulsed frequency, phase, and other parameters, a variety of mixing modes can be achieved, so as to realize the controllable synthesis of nanoparticles in a certain range. By numerical simulation and analysis, the channel section size, entrance angle, and pulse frequency were optimized. Based on the optimized structure and working parameters, the test prototype has been manufactured in lab, and the related synthesis tests of AuNPs were carried out. The test results indicate that AuNPs with uniform morphology and good monodispersity can be synthesized using the system with the section size (0.4 mm × 0.4 mm), the entrance channel angle (60°) under condition of the pulsed frequency (300 Hz), and the entrance flow rate (4 mL/min). The average diameter and its standard deviation of AuNPs synthesized were 21.6 nm, 4.83 nm, respectively. The research work above can be applied to the fields such as the controlled synthesis of noble metal nanoparticles, biomedicine, and microchemical system.
Full-text · Article · Nov 2015 · Advances in Materials Science and Engineering
[Show abstract][Hide abstract] ABSTRACT: Piezoelectric actuation is widely used for the active vibration control of smart structural systems, and corresponding research has largely focused on linear electromechanical devices. This paper investigates the design and analysis of a novel piezoelectric actuator that uses a piezoelectric cantilever beam with a loading spring to produce displacement outputs. This device has a special nonlinear property relating to converting between kinetic energy and potential energy, and it can be used to increase the output displacement at a lower voltage. The system is analytically modeled with Lagrangian functional and Euler-Lagrange equations, numerically simulated with MATLAB, and experimentally realized to demonstrate its enhanced capabilities. The model is validated using an experimental device with several pretensions of the loading spring, therein representing three interesting cases: a linear system, a low natural frequency system with a pre-buckled beam, and a system with a buckled beam. The motivating hypothesis for the current work is that nonlinear phenomena could be exploited to improve the effectiveness of the piezoelectric actuator's displacement output. The most practical configuration seems to be the pre-buckled case, in which the proposed system has a low natural frequency, a high tip displacement, and a stable balanced position.
[Show abstract][Hide abstract] ABSTRACT: A low driving voltage, low cost, high performance insulin delivery system based on PZT actuation is presented in this paper, which consists of two functional units, namely, micropump unit and electronic control unit. The PZT micropump is the core of micropump unit and is the key base to ultimately realize insulin precision delivery of the whole system. The electronic control unit is the important auxiliary unit for the realization of the whole system function. To obtain a higher working performance under low voltage, a serial structure with two chambers and three check valves is adopted in the design of PZT micropump. In place of silicon and glass, main parts of micro-pump unit are manufactured using the polymers which have good biocompatibility, stability and low cost. Through the systematic experimental test for the prototype of PZT insulin delivery system in lab, the maximum backpressure of 14.64 kPa is recorded at applied voltage of 36 V and working frequency of 160 Hz, the maximum flow rate of 5.74 ml/min is obtained in the condition of 36 V and 300 Hz. Under the voltage of 36 V and working frequency of 200 Hz, the micro-dosage pumped by PZT micro-pump displays a good linear characteristic with the number of driving impulses. The minimum resolution of insulin delivery can obtain 3 × 10−4 ml (0.03 U insulin at the concentration of 100 U).
No preview · Article · Dec 2014 · Microsystem Technologies
[Show abstract][Hide abstract] ABSTRACT: Piezoelectric pumps have the potential to be used in a variety of applications, such as in air circulation and compression. However, piezoelectric membrane pumps do not have enough driving capacity, and the heat induced during the direct contact between the driving part and the gas medium cannot be dissipated smoothly. When the gas is blocked, the piezoelectric vibrator generates heat quickly, which may eventually lead to damage. Resonantly driven piezoelectric stack pumps have high performance but no price advantage. In this situation, a novel, resonantly driven piezoelectric gas pump with annular bimorph as the driver is presented. In the study, the working principle of the novel pump was analyzed, the vibration mechanics model was determined, and the displacement amplified theory was studied. The outcome indicates that the displacement amplification factor is related with the original displacement provided by the piezoelectric bimorph. In addition, the displacement amplification effect is related to the stiffness of the spring lamination, adjustment spring, and piezoelectric vibrator, as well as to the systematic damping factor and the driving frequency. The experimental prototypes of the proposed pump were designed, and the displacement amplification effect and gas output performance were measured. At 70 V of sinusoidal AC driving voltage, the improved pump amplified the piezoelectric vibrator displacement by 4.2 times, the maximum gas output flow rate reached 1685 ml/min, and the temperature of the bimorph remained normal after 2000 hours of operation when the gas medium was blocked.
Preview · Article · Mar 2013 · Journal of Mechanical Science and Technology
[Show abstract][Hide abstract] ABSTRACT: As the core part of the electro-hydraulic servo system, the electro-hydraulic servo valve plays an important role in the system. Due to the piezoelectric actuator has characteristics of fast response, easy control and high control accuracy, it can be used as the electric-mechanical converter of the electro-hydraulic servo valve. However, this kind of the piezoelectric direct drive electro-hydraulic servo valve has hysteresis and creep nonlinearities. In order to improve the output accuracy of the system, a high-precise fuzzy control method with the dynamic Preisach model in feedforward loop is proposed. The control scheme is separated into two parts: a feedforward loop with the dynamic Preisach model and a feedback loop with high precise fuzzy control. The high precision fuzzy control adopts Lagrange interpolation method. The experimental results show that the proposed method can resolve the hysteresis and creep nonlinearities and reach a higher dynamic performance, the control effect is better than the conventional fuzzy control method.
Full-text · Article · Jan 2012 · Journal of Advanced Mechanical Design Systems and Manufacturing
[Show abstract][Hide abstract] ABSTRACT: The inert gas fusion and infrared absorption and thermal conductivity methods are widely used for quantitative determination of oxygen(O), nitrogen(N) and hydrogen(H) in metals. However, O, N and H cannot be determined simultaneously with this method in most cases and the sensitivity cannot meet the requirement of some new metal materials. Furthermore, there is no equipment or method reported for determination of Argon(Ar) or Helium(He) in metals till now. In this paper, a new method for simultaneous quantitative determination of O, N, H and Ar(or He) in metals has been described in detail, which combined the pulse heating inert gas fusion with time of flight mass spectrometric detection. The whole analyzing process was introduced, including sample retreatment, inert gas fusion, mass spectral line selection, signal acquisition, data processing and calibration. The detection limit, lower quantitative limit and linear range of each element were determined. The accuracy and precision of the new method have also been verified by measurements of several kinds of samples. The results were consistent with that obtained by the traditional method. It has shown that the new method is more sensitive and efficient than the existing method.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a novel and disposable piezoelectric micropump with high performance for a new closed-loop insulin therapy system. The micropump was designed using four chambers in a serial connection structure, and was manufactured using the materials with good bio-compatibility. The major advantages of the proposed micropump include: possessing high performance under lower working voltage, low-cost, high resolution of flow rate. A maximum backpressure of 22kPa was recorded at an applied voltage of 36Vpp and a driving frequency of 200Hz, the maximum resolution of outflow can obtain 6.23×10−5mL per pulse. Through in vivo animal tests, the new closed-loop insulin therapy system has shown a qualification on controlling blood glucose. The proposed micropump also demonstrated necessary characteristics in terms of stability, accuracy and bio-compatibility, for use in precision insulin delivery.
No preview · Article · Sep 2010 · Sensors and Actuators A Physical
[Show abstract][Hide abstract] ABSTRACT: The factors which influence the pressure of fluid in the Electro-rheological (ER) valve are analyzed; The kinematic equations of ER Fluid under the electric field are established; The prototype of multi-channel cylindraceous ER valve is manufactured based on the technical requirement of ER valve; The flow characteristics of the fluid in the valve are analyzed by the software of Fluent; The test bench of ER valve is built and the influences of the actuator’s driving ability according to the flow acreage of ER valve are analyzed; The static pressure endurable ability of ER valve and the instantaneous hydraulic pressure endurable ability under the circumstance of high speed flow are studied; The characteristics of hydraulic pressure endurable ability of parallel ER valve are obtained.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a piezoelectric stack pump for precise actuator. The piezoelectric pump is characterized by long travel range, precise flow, large driving force, etc. The actuator is controlled by PC and Data Acquisition and Control System (DACS). Simulations and experiments showed that the piezoelectric pump has high efficiency and good performance. With a voltage of 100 V, the flow rate is linear when the rectangle pulses count, so the displacement can be controlled. And its power consumption is low. It studied the effect relationship between frequency and driving velocity under no-load state of the actuator. A multi-chamber pump with buffer chamber structure prevents the valve failure under extreme high pressure. The ultra-precision actuator developed can achieve step resolution 0.038 ¿m. The maximum driving force is 42 N. The maximum driving velocity is 14.8 mm/s and at the best velocity driving frequency is 120 Hz.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a built-in self test pump actuated by piezoelectric bimorphs for fluidic systems. The sensor fabricated by MEMS ensures the flow to be 0.5μ l/s. There are two piezoelectric vibrators in the pump and the check valve is metal cantilever beam. The pump is characterized by integrated structure, flow with built-in self test, wide frequency response, etc. The size of the piezoelectric pump with built-in self test is 30mm, 30mm and 16mm, which is fabricated by precise manufacturing. The high-speed micro processor is used to run the algorithmic program and control the pump with self test. Experiments show that the fuzzy control is fitted for the flow control system. With the appropriate fuzzy rules, the new type of piezoelectric pump can achieve the precision of 0.5μ l/s.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a piezoelectric stack pump for precise actuator. The piezoelectric pump is characterized by long travel range, precise flow, large driving force, etc. Simulations and experiments showed that the piezoelectric pump has high efficiency and good performance. With a voltage of 100V, the flow rate is linear when the rectangle pulses count, so the displacement can be controlled. And its power consumption is low. It studied the effect relationship between frequency and driving velocity under no-load state of the actuator. A multi-chamber pump with buffer chamber structure prevents the valve failure under extreme high pressure. The ultra-precision actuator developed can achieve step resolution 0.038μm. The maximum driving force is 42N. The maximum driving velocity is 14.8mm/s and at the best velocity driving frequency is 120Hz.
[Show abstract][Hide abstract] ABSTRACT: The bearing is an important basic mechanical part for supporting a shaft. A flywheel storage system needs a type of noncontact
support bearing to enhance the speed of the axis. A magnetic suspension bearing is one type of noncontact bearing but has
electromagnetic interference to other electric equipment. Based on the performance research of ultrasonic levitation technology,
a novel noncontact bearing called ultrasonic bearing is presented, which consists of a special piezoelectric vibrator supporting
the load. Experiments are carried out to study the relationships among the amplitude of the vibrator and levitation clearance,
the highest speed of the axis, and the frictional moment of the axis. Results show that the levitation clearance becomes smaller
gradually with increasing load; the rotation speed is up to 8946 r/min, and the friction moment is only 2.095×10−5 N · m when the levitation clearance is 8.53 μm. The ultrasonic bearing is highlighted because of its simple structure, strong
levitation ability, and low friction moment.
No preview · Article · Dec 2009 · Frontiers of Mechanical Engineering in China
[Show abstract][Hide abstract] ABSTRACT: A single vibrator gas piezoelectric micro-pump has been presented in this work. The structure is designed and the dynamic modeling and simulation of the check valve which is the main component of pump are investigated. Based the analysis results, a proto type of gas micro-pump is fabricated and measured. The pump is driven by piezoelectric bimorph which has a hole in the middle, and a check valve is adhered to the hole to cut off fluid. The inlet and outlet is located in the two sides of the piezoelectric vibrator, and the on/off action of the check valve corresponding to the variation of the pump chamber is produced by the actuation vibration energy of piezoelectric vibrator. Compare with the traditional piezoelectric pump which inlet and outlet is located in one side and the check valve of it is driven by differential pressure on the two sides, it has lower fluid resistance and preferable unidirectional cut off characteristic. So the gas pumping ability and the response frequency of check valve are enhanced. The measured output flow rate of present design by experiment reaches 840 ml/min when driving voltage and frequency is 50 V and 1000 Hz.
[Show abstract][Hide abstract] ABSTRACT: The application and working principle of piezoelectric insulin pump are analyzed. The design of using piezoelectric elements to drive the push type insulin pump was proposed. A two serial chamber piezoelectric pump is selected as drive resource and the injector pushed by piezoelectric pump is used to achieve transporting the liquid medicine accurately. The experimental device are designed and researched. The designed piezoelectric insulin pump can transport the liquid medicine and has the self-lock ability meanwhile. Even when the output back pressure is high, the back flow of liquid will not happen. The test results showed: with 180 Hz driving signal, the flow of pump can reach 37.5 ¿L.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a built-in self test pump actuated by piezoelectric bimorphs for fluidic systems. The sensor fabricated by MEMS ensures the flow to be 0.1 mul/s. The pump is characterized by thin structure, precise rate of flow, low power consumption, etc. A prototype of the pump, with a size of 20 mm, 20 mm and 7 mm, is fabricated by precise manufacturing. Simulations and experiments show that the piezoelectric pump has high efficiency and good performance. With a voltage of 75 V, the flow rate is 0.5 mul every three electronic pulses and its power consumption is only 2.6 mW. A robust passive high pressure check valve is developed for piezoelectric actuated pumps. A novel metal check valve flap is used to increase the valve's structural stiffness with pressures up to 20.4 kPa. A series-wound multi-pump chamber structure prevents valve-flap from failure under extreme high pressure.
[Show abstract][Hide abstract] ABSTRACT: Energy generation performance of a piezoelectric generator depends mainly on several elements such as the structural style,
boundary conditions, geometry parameters, materials, vibration-source frequency, and external load. To obtain the optimal
energy-harvesting device, the Raleigh method is used to establish the analysis model of circular piezoelectric composite diaphragms.
Simply supported and clamped boundary conditions were considered. The relationships between the output power and the structural
parameters of piezoelectric composite diaphragms, and the external load resistance and frequency were shown. Given the correlative
material parameters and boundary conditions, the output power, using structural parameters, external load, or vibrating frequency
as variables, can be calculated. Simulation results show that there are optimal structural parameters and load for a composite
diaphragm to achieve the maximum output power. A piezoelectric diaphragm generator with given dimensions tends to achieve
higher output power under clamped boundary conditions than that under simply supported boundary conditions.
No preview · Article · Dec 2008 · Frontiers of Mechanical Engineering in China
[Show abstract][Hide abstract] ABSTRACT: A new precision rotary piezoelectric (PZT) actuator is proposed to improve its drive performance. Based on piezoelectric technology,
the actuator adopts the principle of bionics, with a new method of stator inner anchor/loosen/rotor outer drive and a distortion
structure of a thin shelf flexible hinge. This structure improves the stability of the anchor/loosen and step rotary. Its
characteristics are evaluated by finite element analysis. The experiment shows that the new rotary PZT actuator works with
higher frequency (40 Hz), higher speed (325 μrad/s), wider movement (360°), high resolution (1 μrad/step) and high torque
(30 N·cm). The novel actuator can be applied in wide movement and high resolution driving devices such as those for optics
engineering, precision positioning and some other micro-manipulation fields.
No preview · Article · Aug 2008 · Frontiers of Electrical and Electronic Engineering in China
[Show abstract][Hide abstract] ABSTRACT: A novel piezoelectric (PZT) precision step rotary actuator was developed on the basis of PZT technology. It adopts the principle
of bionics and works with an inside anchoring/loosening of the stator and a distortion structure of the uniformly distributed
thin flexible hinge to solve problems such as ineffective anchoring/loosening, low step rotary frequency, small travel, poor
resolution, low speed and unsteady output. The developed actuator is characterized by high frequency (30 Hz), high speed (380
μrad/s), large travel (>270°), high resolution (1 μrad/step), and work stability. It greatly improves the ability to drive
the existing PZT step rotary actuator. The new actuator can be applied in the field of micromanipulation and precision engineering,
including precision driving and positioning and optics engineering.
No preview · Article · Jun 2007 · Frontiers of Mechanical Engineering in China
[Show abstract][Hide abstract] ABSTRACT: Many of the compounds in drugs cannot be effectively delivered using current drug delivery techniques (e.g., pills and injections). Transdermal delivery is an attractive alternative, but it is limited by the extremely low permeability of the skin. As the primary barrier to transport is located in the upper tissue, Micro-Electro-Mechanical-System (MEMS) technology provides novel means, such as microneedle array and PZT pump, in order to increase permeability of human skin with efficiency, safety and painless delivery, and to decrease the size of the pump. Microneedle array has many advantages, including minimal trauma at penetration site because of the small size of the needle, free from condition limitations, painless drug delivery, and precise control of penetration depth. These will promote the development of biomedical sciences and technology and make medical devices more humanized. So far, most of the insulin pumps being used are mechanical pumps. We present the first development of this novel technology, which can assemble the PZT pump and the microneedle array together for diabetes mellitus. The microneedle array based on a flexible substrate can be mounted on non-planar surface or even on flexible objects such as a human fingers and arms. The PZT pump can pump the much more precision drug accurately than mechanical pump and the overall size is much smaller than those mechanical pumps. The hollow wall straight microneedle array is fabricated on a flexible silicon substrate by inductively coupled plasma (ICP) and anisotropic wet etching techniques. The fabricated hollow microneedles are 200μm in length and 30μm in diameter. The microneedle array, which is built with on-board fluid pumps, has potential applications in the chemical and biomedical fields for localized chemical analysis, programmable drug-delivery systems, and very small, precise fluids sampling. The microneedle array has been installed in an insulin pump for demonstration and a leak free packaging is introduced.
Full-text · Article · Sep 2006 · Microfluidics and Nanofluidics
[Show abstract][Hide abstract] ABSTRACT: As an evangel to diabetics, the invention of insulin pump has drastically renovated the ways of treatment for diabetes. Having been developing since 1970s, insulin pump is an advanced product now. However, the insulin pump in the market is still far from being satisfactory, as pains were caused to patients out of the injection and finger blood extraction. Even worse, if insulin is over injected, the patient can have low blood sugar level that could be life threatening to the patient. And the treatment is expensive to the patients and it is estimated to be 10 RMB/hour due to the high cost of the current insulin systems. It is desirable for regular patients to be provided with a closed-loop, low cost glucose-insulin pump diabetes treatment system, which is not yet available in the market. This closed-loop system will make the glucose measurement and insulin pumping be conducted continuously so that a complete diabetic management can be realized. A novel intelligent insulin pump with painless and automatic injection coupled with the glucose metering was introduced in the present study