Showing papers on "Micropump published in 2001"

Fabrication and characterization of electroosmotic micropumps

Abstract: Electroosmotic flow (EOF) micropumps which use electroosmosis to transport liquids have been fabricated and used to achieve pressures in excess of 20 atm and flow rates of 3.6 μl/min for 2 kV applied potentials. These pumps use deionized water as working fluids in order to reduce the ion current of the pump during operation and increase thermodynamic efficiency. EOF pumps are fabricated by packing the 3.5 μm diameter non-porous silica particles into 500–700 μm diameter fused-silica capillaries and by using a silicate frit fabrication process to hold the particles in place. The devices have no moving parts and can operate as both open (high flow rate) and closed (high pressure) systems. Pressure versus flow rate performance data are presented and combined with measurements of physical dimensions, dry and wet weight, and ion current to calculate the pump structure porosity, tortuosity, effective pore radius, and zeta potential.

A ferrofluidic magnetic micropump

Abstract: A microfluidic pump is described that uses magnetic actuation to push fluid through a microchannel. Operation relies on the use of magnetically-actuated plugs of ferrofluid, a suspension of nanosize ferromagnetic particles. The ferrofluid contacts but is immiscible with the pumped fluid. The prototype circular design demonstrates continuous pumping by regenerating a translating ferrofluidic plug at the conclusion of each pumping cycle. The flow rate can be controlled by adjusting device dimensions or the velocity of an external permanent magnet that directs the motion of the ferrofluid. The ferrofluidic plugs also serve as valves; if the magnetic actuator is stopped, pressure can be maintained with no power consumption. Flow can also be reversed by switching the direction of actuation. The maximum flow rate achieved with minimal backpressure was 45.8 /spl mu/l/min. The maximum pressure head achieved was 135 mm water (1.2 kPa).

A Valve-Less Diffuser Micropump for Microfluidic Analytical Systems

Abstract: The suitability of valve-less micropumps in biochemistry is shown. Fluids encountered in various biochemical methods that are problematic for other micropumps have been pumped with good performance. The micropump is self-priming and insensitive to particles and bubbles present in the pumped media. The results show that the valve-less micropump successfully pumps fluids within the viscosity range 0.001–0.9 Ns/m2. The micropump is not sensitive to the density, ionic strength or pH of the pumped media. Effective pumping of solutions containing beads of different sizes was also demonstrated. Living cells were pumped without inducing cell damage and no cell adhesion within the pump chamber was found.

Design and simulation of an implantable medical drug delivery system using microelectromechanical systems technology

Abstract: A unique design of an implantable micropump for medical drug delivery systems was proposed The peristaltic pumping principle was selected Three pump chambers are individually actuated by each bulk PZT (lead zirconate titanate) disk in a peristaltic motion It is this peristaltic motion that propels the fluid The design of the micropump includes inlet, three pump chambers, three silicon membranes, three normally closed active valves, three bulk PZT actuators, three actuation reservoirs, flow microchannels, and outlet To prohibit flow when no power is applied, the micropump was designed to be normally closed The pump features an integral valve/membrane design such that the pump chambers not only pump the liquid, but also function as the inlet and outlet valves To determine the dimensions of the proposed micropump, analytical modeling of the micropump chamber was conducted The design tradeoffs between maximizing the pumped volume and reducing the overall size of the proposed micropump were analyzed An electromechanical coupled field simulation using the FEA method was employed Based upon the simulation results, 6 and 12 mm diameter silicon membranes with different thickness of 40 and 80 μm were fabricated using microelectromechanical systems (MEMS) technology The deflection of these silicon membranes was tested The PZT actuator was manually glued onto the micropump chamber The testing data agreed well with the FEA simulation of the deflection The conductive adhesive layer dramatically reduces the deflection A 12 mm in diameter and 40 μm thick silicon membrane in each pump chamber is needed to meet the micropump design requirements The fabrication and experiments of these silicon membranes reported in this paper determine the dimensions and fabrication processes for the complete micropump A 70 mm ×35 mm ×10 mm micropump will be fabricated using MEMS fabrication technology The complete micropump will be characterized to verify our design

Fabrication of TiNi shape memory micropump

Abstract: We have developed a shape memory alloy (SMA) actuated micropump as a component for use in micro analysis or micro dosage systems. In this paper, we will discuss the fabrication process and dynamic actuation properties of an SMA actuator, as well as the first result of pumping properties of a completed SMA micropump. TiNi thin film of about 6 μm in thickness was deposited onto a Si wafer with a square recess on its reverse side, and memorized an initial flat shape. The TiNi thin film and a Pyrex glass cap with a square recess were then anodically bonded together in a vacuum to form a chamber to which a bias pressure was to be applied to deform the TiNi thin film. After removing the remaining Si layer beneath the TiNi thin film by RIE in SF6 plasma, a shape memory actuator of 5 mm square in size was completed. A Si check valve structure was also fabricated through a process of anisotropic etching and fusion bonding and was assembled with the actuator. The fabricated micropump with a size of 10 mm ×20 mm ×1.4 mm was driven by thermal cycles of resistive heating and air-cooling under bias pressure which was applied by a nitrogen gas flow. The completed SMA micropump proved to give a flow rate of 0.4 μl per cycle at a bias pressure of 100 kPa.

An electrohydrodynamic polarization micropump for electronic cooling

Abstract: This paper presents the design, fabrication, and characterization of an innovative microcooling device for microelectronics applications. The device incorporates an active evaporative cooling surface, a polarization micropump, and temperature sensors into a single chip. The micropump provides the required pumping action to bring the working fluid to the evaporating surface, allowing the effective heat transfer coefficient through a thin-film evaporation/boiling process. The device is based on VLSI microfabrication technology, allowing the electrohydrodynamic (EHD) electrodes to be integrated directly onto the cooling surface. Since the EHD electrodes are fabricated using the same technology as the electronic systems themselves, the proposed microelectronic cooling system in the form of an integrated microchip is very suitable for mass production. The prototype devices demonstrated a maximum cooling capacity of 65 W/cm/sup 2/ with a corresponding pumping head of 250 Pa. The results of this investigation will assist in the development of future microcooling devices capable of operating at high power levels.

Miniature valveless pumps based on printed circuit board technique

Abstract: This paper presents a new concept of designing microfluidic devices. By using printed circuit board (PCB) as the substrate material, miniature valveless pumps have been successfully developed. The pump can be operated as a single diffuser/nozzle pump or a peristaltic pump, and can delivery a maximum flow rate of 3 ml/min. The detailed design, fabrication, and characterization of the pumps are described in the paper. The PCB technique presents a low-cost and flexible alternative for small-scale production of microfludic devices.

Characteristics and fabrication of NiTi/Si diaphragm micropump

Abstract: A novel micropump actuated by NiTi/Si composite diaphragm was described in this paper. The driving principle, microfabrication processes and characteristics of the pump were reported. The pump is composed of a deformable chamber and two silicon flap check valves. The outer dimension of the pump is 6 mm ×6 mm ×1.5 mm , with the diaphragm size of 3 mm ×3 mm ×20 μm. The fabrication processes include silicon micromachining and AuSi eutectic bonding. By using the recoverable force of NiTi thin-film and biasing force of silicon membrane, the actuation diaphragm realized reciprocating motion effectively. Experimental results show that the pump has superior performance, such as high pumping yield (up to 340 μl/min), high working frequency (up to 100 Hz), and long fatigue life time (more than 4×107 working cycles).

A self-filling micropump based on PCB technology

Abstract: This paper presents a novel micropump based on printed circuit board technology (PCB). The pump consists of four PCB layers and one membrane layer forming two passive check valves and one thermopneumatically driven volume actuator. Due to the large deflections of the actuator membrane, the device is completely self-filling and able to pump liquids even with gas bubbles. A maximum flow rate of 530 μl/min (using water) and a back-pressure of 119 mbar are obtained by an average power consumption of 1 W and an exciting frequency of 1 Hz.

A high-performance silicon micropump for disposable drug delivery systems

Abstract: This paper describes the design, fabrication and experimental results of a new, low cost, high-performance silicon micropump developed for a disposable drug delivery system. The pump chip demonstrates linear and accurate (/spl plusmn/5%) pumping characteristics for flow rates up to 2 ml/h with intrinsic insensitivity to external conditions. The stroke volume of 160 nl is maintained constant by the implementation of a double limiter acting on the pumping membrane. The actuator is dissociated from the pump chip. The chip is a stack of three layers, two Pyrex wafers anodically bonded to the central silicon wafer. The technology is based on the use of SOI technology, silicon DRIE and the sacrificial etch of the buried oxide in order to release the structures. The result is a small size chip, suitable for cost-effective manufacturing in high volume. The micropump chip is integrated into the industrial development of a miniature external insulin pump for diabetes care.

Bubble-based micropump for electrically conducting liquids

Abstract: This paper describes a novel pumping device without mechanical moving parts based on the periodic generation and collapse of a single vapour bubble in a channel. The channel shape is such that it creates an asymmetry in the surface tension forces, which results in a pumping effect. The principle can be implemented over a broad range of channel sizes and repetition frequencies. For illustration purposes, a particular implementation is described here where the working fluid is a salt solution in water, the channel diameters are of the order of 1 mm and the repetition frequency is between 1-10 Hz. In these conditions, the device develops a head of a few centimetres of water with typical flow rates in the range of 100 µl per minute. It appears possible to increase both head and flow rate by adjusting geometrical parameters and operating conditions. A simple modification of the design would render the same principle also applicable to the pumping of non-conducting liquids.

Micropumps: summarizing the first two decades

Abstract: Among the large number of microfluidic components realized up to now, micropumps clearly represent the case of a 'long runner' in science. A brief literature review reveals, that one of the first scientific papers on a micropump dates from 1978, which is more than two decades ago. An increasing number of publications is found from that time on representing widespread research activities, and there seems to be no change of this trend. An astonishing diversity of micropump concepts and devices has emerged until today, reaching from peristaltic micropumps to a large number of micro diaphragm pumps to recent high-pressure devices without any moving parts. Electrohydrodynamic, electroosmotic, electrostatic, electromagnetic, magnetohydrodynamic, SMA, piezoelectric, thermopneumatic, hydraulic or pneumatic - almost every MEMS-based or mesoscopic actuation principle has been combined with micropumps. An outstanding diversity is also found in the fabrication technology - the span reaches from silicon-based devices over precision machining to injection moulding. This altogether makes it worth to summarize and also take a look into the future of micropumps - after the first two decades.

Magnetically-actuated micropump

Abstract: A microfluidic pump having a substrate with a pump chamber and at least one channel in communication with the pump chamber for transporting a substance into or out of the pump chamber. A flexible diaphragm overlies the pump chamber, and a magnetic member is attached to the diaphragm. A magnet, such as an electromagnet, is positioned to attract and repel the magnetic member, thereby actuating the diaphragm, and causing a substance to be drawn into or out of the channel. A uni-directional or bi-directional check valve can be positioned in the channel to prevent backflow into the pump chamber. A control system can be coupled to the pump to adjust actuation rate of the diaphragm.

Analytical solutions for the dynamic analysis of a valveless micropump — a fluid–membrane coupling study

Abstract: A non-linear vibration model for fluid–membrane coupling is developed for simulating the behaviour of valveless micropumps. The analytical solution for fluid–membrane coupling vibration has been approximated using the Galerkin and small parameter perturbation methods. Specifically, the vibration response of the membrane and the mean flux through a valveless membrane micropump are investigated in detail. The effects of the pressure loss coefficients of the diffuser and the coupling parameter on the mean flux are examined. An optimal working frequency range for the valveless membrane micropump is obtained. Numerical examples are presented to demonstrate the effectiveness of the present model for the designing of valveless micropumps.

A Piezoelectric Valve-Less Pump-Dynamic Model

Abstract: A complete dynamic model for the simulation of the valve-less piezoelectric pump performance is presented, In this model the piezoelectric action is considered as a periodic force acting on a pumping membrane. The natural frequency of the pump is calculated as well as its performance as a function of the driving frequency, The effect of the deviation of the driving frequency from the natural frequency on the pump performances is clearly shown. Also, it is demonstrated that the effect of the liquid mass in the pump nozzles on the natural frequency of the system is very high owing to the high acceleration of the fluid in the nozzles. Comparison with experiments shows a very good agreement with a minimal number of adjusting parameters.

Modelling and test of a thermally-driven phase-change nonmechanical micropump

Abstract: A thermally driven phase-change nonmechanical micropump has been investigated theoretically and experimentally This micropump consisted of a microchannel and a number of uniformly-spaced heating elements along the channel The pumping of fluids in such a pump was realized by using the actuation of a moving vapour slug (bubble) generated by suitably phased heating elements The pumping mechanism was studied theoretically by considering a liquid-filled tube heated locally by a moving heating source To verify the theoretical analysis, a pumping device consisting of a microchannel with twelve embedded heaters along the channel was fabricated and tested using deionized water as the working fluid The experimental results indicate that this simple micropump can achieve a maximum pressure head of 57 mm H2O and a maximum volumetric flow rate of 300 µl min-1 when it is operated for a heating power ranging from 80 to 120 W and a heating time of about 3 s It is found that the theoretical model is in reasonable agreement with the experimental data

A micropump driven by continuous electrowetting actuation for low voltage and low power operations

Abstract: In this paper we first report a micropump actuated by continuous electrowetting (CEW). We have used the surface-tension-induced motion of a mercury drop in the microchannel filled with an electrolyte as actuation energy. We have fabricated the CEW actuator, silicone rubber pumping membranes and copper flap check valves, and have demonstrated actual liquid pumping up to 63 /spl mu/l/min at the applied voltage of 2.3 Vpp. The maximum pump pressure is about 600 Pa at the applied voltage of 2.3 Vpp with operation frequency of 10 Hz.

Active disposable microfluidic system with externally actuated micropump

Abstract: The present invention is a microfabricated system for performing biochemical analysis on a test sample of substance. The system includes a substrate with a sample entry port, one or more pump chambers, and one or more mixers. Channels are connected between the pump chambers and the mixers to conduct the flow of the substance during the processing. A magnetic member is positioned on a diaphragm over each pump chamber, creating a pump that is actuated by attracting and repelling the magnetic member with a magnet. Each magnetic member is attracted or repelled independently of the other magnetic members.

Gas cushion proportioning microsystem

Abstract: A gas cushion proportioning microsystem to proportion liquid volumes in the microliter and sub-microliter ranges, comprising a liquid reservoir including a storage space for the liquid being proportioned the boundary line of which is broken through by an outwardly leading liquid passage and a gas passage, a gas displacement system which has a micropump to pump a gas and a connection to the gas passage, and a proportioning control in an operative communication with the micropump to generate a negative pressure or positive pressure by actuating the micropump and to apply the negative pressure or positive pressure to the liquid reservoir in order to receive liquid in the storage space through the liquid passage or to deliver it from said space.

Integrated micropump analysis chip and method of making the same

Abstract: An integrated micropump or a plurality of integrated micropumps are communicated to a plurality of analysis chambers. A plurality of integrated analysis chambers include integrated analysis devices to test a fluid for an analyte. The micropumps continuously or periodically pump the fluid into the analysis chambers and flush the analysis chambers after analysis of the analyte. In one embodiment, the analysis device comprises an integrated LED and an integrated optical detector. The LED and detector are tuned to an optical absorption line of the analyte. The micropumps are composed of nitrides of B, Al, Ga, In, Tl or combinations thereof and fabricated using photoelectrochemical techniques. The analysis chambers, and micropumps including the analysis devices are simultaneously fabricated during which fabrication of the micropumps and the analysis devices are masked from the photoelectrochemical techniques.

Analytical study of microchannel and passive microvalve: application to micropump simulator

Abstract: Microfluidic systems including microchannels and microvalves, fabricated by micromachining technology, are studied with approached models, either analytical or by simulation. The modelling of rectangular channel and passive valves is presented in this paper, which is divided in three parts. At first, the analytical modelling of a channel versus its shape factor and a normalisation of its fluidic comportment is presented. Then a description of the diffuser-nozzle valve is purposed by applying the general Bernoulli equation. The efficiency of this valve is found to be determined by the value of the shape factor and angle of the diffuser element. The third part is dedicated to numerical simulation of a Tesla diode and purpose an optimisation of its efficiency versus the Tesla geometry. Finally, the realisation and characterisation of prototypes are exposed. Characterisation were applied to rectangular channel and showed good agreement with the analytic modelisation. The analytic expressions, that have been found, can be used in simulations of the flow sensors through the construction of an equivalent electric circuit, and subsequently analysed using SPICE or similar tool Simulink Matlab.

Micromotors, linear motors and microactuators for controlling flow properties of fluids

Abstract: The use of an electro-sensitive movable fluid, that is, a micromotor, a linear motor, a micropump and a method of using the micropump, a microactuator, and an apparatus which these devices are applied to, and a method and apparatus of controlling flow properties of a fluid.

A Micromachined Silicon Low-Voltage Parallel-Plate Electrokinetic Pump

Abstract: Interest is increasing in the development of electrokinetic pumps capable of generating high flow rates (> 1 ml/min). These pumps are suitable for applications such as microcooler systems. Electrokinetic pumps offer the considerable advantages of simple architecture, no moving parts, low power consumption, and robust operation. Large electric potentials are typically involved in the operation of electrokinetic devices, limiting the use of silicon in such devices. We have devised a pump design that addresses this problem. The performance of test devices of this new design suggests that electrokinetic pumping is a viable option for fluid transport and fluidic actuation in silicon micromachined devices.

Microdosing system with gas cushion

Abstract: Gas cushion micro-dosing system for dosing liquid volumes in the microliter and sub-microliter range with a liquid reservoir with a storage space for the liquid to be metered, whose boundary is pierced by an outwardly leading liquid passage and a gas passage, a gas displacement system having a micro pump for pumping a gas and a connection with the gas passage and is in operative communication with the micropump metering control for generating a negative pressure or positive pressure by actuating the micropump and for pressurizing the fluid reservoir with the vacuum or overpressure to receive fluid through the fluid passage into the storage space or to emit therefrom.

Ceramic magnetohydrodynamic (MHD) micropump

Abstract: Magnetohydrodynamic (MHD) pumping has several attractive features including no-moving-parts operation, compatibility with biological solutions, and bi-directional pumping capability. In this work, a re-circulating ceramic MHD micropump is described. The MHD operation principle is based on the generation of Lorenz forces on ions within an electrolytic solution by means of perpendicular electric and magnetic fields. These Lorenz forces propel the ions through a channel, thus creating a net flow with no moving parts. Fabrication of the pumps is achieved by means of a new ceramic MEMS (CMEMS) platform in which devices are built from multiple layers of green-sheet ceramics. The major advantage to this technology is that unlike many other fabrication technologies, the multi-layer ceramic CMEMS platform is truly three-dimensional, thus enabling the building of complex integrated systems within a single platform. The ceramic-based MHD pumps have been analyzed and tested using both finite element modeling and experimental validation. Test results indicate that the pumps are capable of pumping a wide range of biological fluids in the flow rate range of microliters per minute. Additionally, good stability over 24 hours and good correlation with modeling data have been verified.

Gas cushion type distribution microsystem

Abstract: PROBLEM TO BE SOLVED: To provide a gas cushion type microsystem for distributing liquid in an extremely trace liquid quantity of a microliter and a range not more than the microliter SOLUTION: In this gas cushion type distribution microsystem for distributing the liquid in a liquid quantity of a microliter and a range not more than the microliter, the gas cushion type distribution microsystem has a liquid storage part being a storage space of the distributing liquid and including a part forpassing a liquid passage extending outward to a boundary line and a gas passage, a gas displacement system having a micropump for pumping gas and a connecting part to the gas passage and a part being a distribution control part operated and communicated with the micropump and receiving the liquid to the storage space or delivering the liquid from the space via a liquid passage by adding negative pressure or positive pressure to the liquid storage part by generating the negative pressure or the positive pressure by actuating the micropump

Micropump design for optimum pressure/flow characteristics

Abstract: Until now there have been no reports of design techniques that include a means for developing pumps that can pump against higher pressure loads at the cost of less volume flow rate delivered to the load or vice versa. We address this problem for membrane micropumps that incorporate no-moving-parts valves (NMPV). A design approach is presented that utilizes a linear low-order model, finite element analysis to optimize piezoelectric actuation, and an algorithm to interrogate a design space of membrane thickness and valve size for any specified pressure load. The results indicate that optimum designs are relatively far from existing pumps and that significant improvements are possible. These gains appear to be due to the ability of the design approach to select non-obvious combinations of membrane stiffness and valve size to better “tune” the system, which is crucial in the case of NMPV pump, because excellent resonant behavior can make up for the fact that the valves do not open and close. Another important observation was that the optimal design point for pressure was not the same as for flow. This result is an indication that pumps can be designed for pressure or flow through careful design.

Micropump, micromixer, micromachine device, micro movable mirror and optical switch

Abstract: PROBLEM TO BE SOLVED: To provide a micromachine that is inexpensive and disposable by using an epoxy-based photosensitive resin and easily ensuring an increased wall thickness without lamination, and a manufacturing method thereof. SOLUTION: A micromachine device comprises an epoxy-based photosensitive resin itself as a structural material. A semiconductor photolithography technique can prepare by batch treating three-dimensional structure of resin without an assembly process to thereby facilitate microminiaturization and complication of a resin device and reduce cost. Enabled integration with a processing circuit can repress a problem of, for example, stray capacity to enable incorporation of a device such as a high precision sensor.

Micropump underpressure control device

Abstract: A micropump underpressure control device, working in conjunction with a micropump having an inlet and an outlet. The micropump underpressure control device comprises a control valve and a transmission tube. The control valve is installed at a supply pipe leading to the micropump and further comprises a case with a membrane, a valve assembly, a connecting rod and a spring. The membrane is exposed to pressure from the outlet of the micropump and accordingly deformed, via the connecting rod controlling opening and closing of the valve assembly, so that working liquid is allowed to proceed to the inlet of the micropump or blocked. The transmission tube transmits pressure at the outlet of the micropump to the membrane. On an opposite side, the membrane is pressed on by working liquid and by the spring. Thus pressure at the inlet of the micropump is controlled, being kept smaller than or equal to pressure at the outlet of the micropump by a fixed difference.