Showing papers on "Micropump published in 1995"

A bidirectional silicon micropump

Abstract: In this paper we present a bidirectional silicon micropump. It consists of an electrostatically actuated diaphragm and two passive check valves. It differs from other well-known diaphragm pumps, generally referred to as unidirectional pumps, in the layout of the valves. We have designed a flap valve with a first mechanical resonance frequency between 1 and 2 kHz (in the fluid environment). At low actuation frequencies (0.1–800 Hz), the pump works in the forward mode. At higher frequencies (2–6 kHz) the pump operates in the reverse direction. This is due to a phase shift between the response of the valves and the pressure difference that drives the fluid. Investigating different pump layouts, we achieve maximum pump rates of 250 and 850 μl min -1 in the forward direction as well as 400 and 200 μl min -1 in the reverse direction. The maximum back pressure is 31 000 Pa (3.1 m H 2 O) in the forward and 7000 Pa (0.7 m H 2 O) in the reverse direction.

Working principle and performance of the dynamic micropump

Abstract: This paper deals with a piezoelectrically driven micropump of the reciprocating type. For the flux rectification, so-called dynamic passive valves, particularly shaped micro channels having a direction-dependent fluid-dynamic behaviour, are used. This solution renders the pump structure extremely simple and makes the fabrication process cheap. Also, further miniaturization becomes possible. Typical working parameters are zero-load pump rates of several hundred microlitres per minute and pump pressures of up to 7 kPa. The upper frequency limit is as high as about 10 kHz. Thus, pumping of gases at resonance operation also becomes possible. A quasistatic model has been developed which enables an optimized application-oriented layout process to be carried out.

Micropumps with fixed valves

Abstract: Micropumps fabricated by micromachining techniques and employing fixed or no-moving-parts valves. As one aspect of the invention, a laser-assisted chemical etching technique is employed for providing smooth-walled, curved configuration necessary to obtain the desired flow characteristics of the valves that are used in conjunction with the micropump.

Fluid micropumps based on rotary magnetic actuators

Abstract: A jet-type magnetically driven fluid micropump to drive conductive fluids has been designed, fabricated, and tested The pump actuation is based on a rotary magnetic micromotor with fully integrated stator and coils operating with the rotor immersed in the fluid to be pumped, thereby driving the fluid from a inlet flow reservoir through integrated flow channels to an outlet flow reservoir The micropump has been successfully driven using standard diabetic-prescription insulin in saline buffer (Novo Nordisk, Regular Insulin) as a working fluid, demonstrating the feasibility of a rotary micropump for pumping and injecting fluids in drug delivery or chemical flow systems The attained flow rate varies monotonically with motor speed In the realized micropump, the fluid flow rate achieved is up to 24 p!/min at a rotor speed of 5000 rpm The operating voltage is less than 3 V and the power consbmption is approximately 05 W The differential pressure is expected to be approximately 100 hPa

A piezoelectric-driven stereolithography-fabricated micropump

Abstract: The design and fabrication of hydraulic microcomponents obtained by stereolithography are proposed in this paper. A piezoelectric micropump and microchannels have been fabricated and tested extensively. The pump body and the microchannels are made out of ultraviolet-photocurable polymer material and manufactured by a single stereolithographic process. Stereolithography has been selected since it allows the microfabrication of three-dimensional structures of any complex shape, even incorporating 'integral' movable parts that may require no assembly. The design of the pump body and the flow channels has been based on optimum hydraulic criteria, and aimed to obtain long life and quick, cheap and easy manufacturing. Design rules have been studied in order to obtain hydraulic components with specific behaviours (flow rate, head, loss and charge). The paper describes the finite-element analysis of the thin plate pumping element and of the actuator, as well as the fabrication and experimental performance of the pump. Experimental results show good agreement with theoretical prediction obtained by simulation, and values of flow rate and discharge head that are among the highest reported in the literature for pumps for similar size and working principles.

A bidirectional silicon micropump

Abstract: In this paper we present a bidirectional silicon micropump. It consists of an electrostatically actuated displacement unit and two passive check valves. The difference to other wellknown diaphragm pumps, which are known as unidirectional pumps, is the layout of the valves. We designed a flap valve with a first mechanical resonance frequency between 1 WIZ and 2 WIZ (in the fluid environment). At low actuation frequencies (0,l Hz 800 Hz) the pump works in the forward mode. At higher frequencies (2 kHz - 6 kHz) the pump operates in the reverse direction. This is due to a phase shift between the responds of the valve and the pressure difference which drives the fluid. Investigating different pump layouts we achieved maximum pump rates in forward (reverse) direction of 250 (350) pYmin and 850 (200) flmin. The msori" back pressure is 3 10 hPa in forward and 70 hPa in reverse direction.

A new micropump principle of the reciprocating type using pyramidic micro flowchannels as passive valves

Abstract: The working principle of a dynamic micropump is presented and its basic parameters are discussed. The dynamic micropump has a very simple and cheap structure consisting of a pump chamber, an oscillating membrane and two truncated pyramid shaped microchannels produced by anisotropic etching of silicon. The latter show a direction-dependent behaviour of their flow resistances, for which reason they provide as so-called dynamic passive valves, a partial rectifying of an alternating flux. The simple mechanical system of the micropump enables high working frequencies between 100 Hz and 10 kHz; the zero-load pump rate is equal to or higher than 250 mu l min-1, being up to one-order of magnitude more than the micropumps so far developed can provide. The pump parameters can be chosen in a wide range by simply changing the size of the dynamic valve channels.

Method and device for driving a micropump

Abstract: The control system is used for a micro-membrane pump(100) which has a feed direction defined by its valve structure(118,120), with selective reversal of the feed direction when a driver signal with a given energising frequency is supplied to the pump. The energising frequency is in a frequency range above the resonance frequency of the resonating system provided by the moving parts (106,118,120) of the pump and the pumped fluid, with a phase difference of between 90 and 180 degrees between the driver signal and the deflection of the valve structure.

Transient measurements on miniaturized diaphragm pumps in microfluid systems

Abstract: In this paper the dynamics of miniaturized diaphragm pumps will be investigated by transient pressure measurements on the millisecond time scale. The results will be compared with simulations. It will be shown that there is a strong interaction between the dynamics of miniaturized diaphragm pumps and the geometry of the connected fluid channels, caused by the inertia of the fluid.

Portable medical pump device

Abstract: A medical micropump device having a pump for injecting a liquid material which includes a housing (12) with a first rotational side wall (18), a flexible tubing (16) which has a first end connected to the pump and a second free end, and a hollow rotational pump support (14) containing the pump housing (12). The pump support (14) allows access to at least the major portion of one of the side surfaces of the pump housing (12) and surrounds at least partially the rotational side wall of the housing (12) to form a winding space (26) for receiving the tubing reel (16). The pump support (14) has at least one opening on its peripheral surface through which extends the free end of the tubing (16), means for rotationally guiding the pump housing and coupling means for preventing the free separation of the pump support and the pump housing. The device provides a portable winding apparatus with the possibility of adjusting the length of the tubing connecting the micropump to the injection site.

Modular concept for miniature chemical systems

Abstract: Miniaturised chemical systems comprise components for fluid manipulation (channels, pumps, valves etc.), (bio)chemical reaction and analysis. We propose a generic concept consisting of a so-called Mixed Circuit Board (MCB) containing both the fluidic channels and electrical circuitry as well as the silicon-based modules. The modules have a standardized connection to the MCB both for fluids as for electrical signals. In- and output modules have connections with capillaries used for liquid chromatography, ensuring the compatibility with this separation technique. The MCB itself consists either of glass-bonded silicon with anisotropically etched channels, but can ultimately be made as plastic component with use of moulding techniques. A number of system components such as a micropump, a capillary connector, a flow sensor, a micromixer (reactor) and a microfilter will be presented. An example of an electrochemical microreactor (microtitrator) will be given, and it will be shown how incorporation of this microreactor in a Micro Total Analysis System (μTAS) improves its performance. Finally a potential future realisation of a more complicated system, a parallel multisystem for chemical processparameter optimisation, will be evaluated.

Development of passive microvalves by the finite element method

Abstract: The combination of a stiff titanium membrane and a flexible polyimide membrane was used to form a check valve for a micropump. This work is concerned with calculating the performance of such a microvalve and modifying its design so that instead of acting as an inlet valve, it functions as an outlet valve. It will be demonstrated here by application of the finite element method how design solutions can be found to this problem. Both the deflection behavior of the microvalve membrane exposed to the pressure and the stresses generated at the clamping points of the membrane structures have been calculated.

Working principle and performance of the dynamic micropump

Abstract: Dynamic micropumps employing pyramid-trunc shaped diffusers as dynamic passive valves have been developed, built and tested They are particularly characterized by a very simple fabrication technology and good high frequency performance A prototype being 5*5*lmm/sup 3/ in size reached with methanol a zero load pump rate of more than 300 /spl mu/l/min and a maximum pump pressure of about 7 kPa at 5 kHz working frequency Dynamic micropumps can, therefore, compete with known solutions of similar or even bigger size The direction-dependent behaviour of silicon microdiffusers have been experimentally investigated; the results are discussed Based on the found characteristics, a static model for dynamic membrane pumps has been derived The calculated parameters match quite well the real values of different tested micropumps By the static model, pump layout adapted to the demanded application becomes easier

Static And Dynamic Flow Simulation Of A Koh-etched Micro Valve

Abstract: In this paper, we present the simulation of the flow rate through a KOH-etched micro valve, which is part of an electrostatically actuated micropump. This is realized by a coupled simulation of liquid flow and structural displacement of the valve using the Finite-Element-Method. Thereby the static and dynamic behaviour of the valve can be simulated in good agreement to measurements. In combination with anallytical approaches the simulations can be integrated into system simulations. The results are of basic importance for the understanding and optimization of bi-directional silicon micropumps.

Specific Problems of FEM Thermal Simulations for Microsystems

Abstract: Microsystems often require special attention to the thermal aspects, as they frequently integrate severe heat sources together with electronics. When Finite Element Method programs are used for the solution of these problems, difficulties different from normal ICs are encountered, like, for example, thin membranes with huge aspect ratios and natural and forced convection in microcavities. Some of these aspects are discussed for the example of ANSYS 5.1 simulations of a 3-D multichip microsystem including a thermopneumatic micropump. 1. Heat transport mechanisms in a microsystem Fig. 1 shows an example of a microsystem investigated in the European ESPRIT project BARMINT. It consists of a set of up to ten chips with variable functions. The chips are glued onto a silicon support, stacked and cast in epoxy. The resulting epoxy cube is reduced in size by sawing. During this step, the supports are also sawn through revealing cross-sections of the metal tracks. After metallizing the cube the metal is patterned by laser patterning. As well as the micropump the cube includes sensor, supply, test and signal processing chips. The sensor chip constitutes the bottom part of the liquid flow channel for the chemical and physical analysis and it is bonded onto a 1mm thick PYREX glass. The system is designed as a demonstrator for compatibility for biomedical applications. The pump is driven by thermopneumatic actuation. The power management of the system is of prime importance: consumption of the pump should be minimized and the temperature at the chips containing electronics Transactions on the Built Environment vol 12, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509