Abstract: A magnetohydrodynamic fluidic system includes a reagent source containing a reagent fluid and a sample source containing a sample fluid that includes a constituent. A reactor is operatively connected to the supply reagent source and the sample source. MHD pumps utilize a magnetohydrodynamic drive to move the reagent fluid and the sample fluid in a flow such that the reagent fluid and the sample fluid form an interface causing the constituent to be separated from the sample fluid.

Abstract: A magnetohydrodynamic pump for pumping a fluid. The pump includes a microfluidic channel for channeling the fluid, a MHD electrode/magnet system operatively connected to the microfluidic channel, and a system for promoting flow of the fluid in one direction in the microfluidic channel. The pump has uses in the medical and biotechnology industries for blood-cell-separation equipment, biochemical assays, chemical synthesis, genetic analysis, drug screening, an array of antigen-antibody reactions, combinatorial chemistry, drug testing, medical and biological diagnostics, and combinatorial chemistry. The pump also has uses in electrochromatography, surface micromachining, laser ablation, inkjet printers, and mechanical micromilling.

Abstract: An electrohydrodynamic (EHD) conduction pump is provided for pumping dielectric liquids, and a particular adaptation for mass transport of isothermal and non-isothermal single phase liquids. The EHD conduction pump does not require direct injection of electric charges into the fluid. The EHD conduction pump includes an EHD pumping section and associated connecting tubes with electrodes arranged in series in the pumping section. The electrodes are coupled to a high voltage low current dc power supply. A positive polarity dc voltage is applied to the electrodes. Various electrode configurations may be used, such as three-needle, hollow-tube, or pin-needle electrode configuration.

Abstract: A blood pump intended to be carried by a freely moving patient uses perpendicular magnetic and electrical fields to propel blood. A rod mounted coaxially inside a tube has electrodes in blood contact for establishing a radial electric field, and an inductor having windings parallel to the axis of the tube is used to establish a circumferential magnetic field. To avoid the evolution of gas at the electrode surfaces the magnetic and electric fields are periodically reversed, and the electrodes are made to have very high surface areas. The blood pump is powered by batteries or fuel cells (or a combination of both) to provide long service between recharging and to reduce the weight carried by the patient.

Abstract: The sputter ion pump includes a vacuum chamber that includes an inner wall having a cylindrical section which is rugged in cross section. The rugged cylindrical section has outer recesses each of which is provided with a permanent magnets, each magnet having a same shape and a same characteristic so that a magnetic pole is directed to a same direction. The rugged cylindrical section has also inner recesses each of which is provided with a cylindrical anode electrode member spaced from the vacuum chamber wall. The rugged cylindrical section of the vacuum chamber wall is formed as a cathode electrode. A cylindrical shield member having a peripheral portion provided with evacuating bores is provided coaxially to the permanent magnets and anode electrodes. The permanent magnets and anode electrode members are arranged with equal spacing in an axis symmetrical configuration.

Abstract: The present invention generally provides a micropump that utilizes electroosmotic pumping of fluid in one channel or region to generate a pressure based flow of material in a connected channel, where the connected channel has substantially no electroosmotic flow generated. Such pumps have a variety of applications, and are particularly useful in those situations where the application for which the pump is to be used prohibits the application of electric fields to the channel in which fluid flow is desired, or where pressure based flow is particularly desirable.

Abstract: A plasma pump and method for pumping ions from a first to second region, the pump including a partition member having a through opening defining a plurality of conduits (30); a group of magnets (24) to provide magnetic forces that extend to the conduits; and a plurality of electric potential sources (14) for creating electrostatic fields which accelerate ions from the conduits to the second region.

Abstract: A microfluidic system has an electroosmotic flow (EOF) pumping means for propelling fluids through a series of microchannels and selection valves. Pump channels are configured in groups which may be fabricated singly or in multiple groups onto a substrate. A bubble-free electric connection joint provides for the application of voltages across pump channels while simultaneously blocking the passage of fluids through the joint. Bubble-free electrodes are also provided to prevent electrolysis and bubble formation in or close to the microfluidic channels. The selection valves provide for routing functions within the microfluidic system and can also be configured to route fluids outside the system. A rate monitoring system is provided for determining and compensating for system flow rates. In one application the microfluidic system may be configured to operate as a small volume pipettor or other fluid transport or analysis device.

Abstract: There is provided a sputter ion pump that it has a simple structure, a size and a weight can be reduced, the magnetic fields in the vicinity of a central axis can be nullified in the both of a radial and axial directions, and ultimate pressure of the pump can be increased.

Abstract: A cooling system employing Micro Electro Mechanical System (MEMS) technology and polarization principles to move a cooling fluid over a surface requiring cooling and further employing electrohydrodynamic principles for the purpose of enhancing the heat transfer coefficient between the cooling fluid and the surface to be cooled.

Abstract: A plasma pumping cell and method for pumping ions from a first region containing a plasma to a second region when the plasma pumping cell is interposed between the first and second regions, the plasma pumping cell including: a partition member (4) positioned between the first and second regions, the partition member (4) having a through opening defining a conduit (22); a plurality of magnets (24) positioned relative to the conduit in a manner to provide lines of magnetic force that extend through the conduit; a source of free electrons in communication with the conduit; and an electric potential source (34) disposed relative to the conduit to create an electrostatic field which accelerates ions from the conduit (22) to the second region.

Abstract: The present invention generally provides a micropump that utilizes electroosmotic pumping of fluid in one channel or region to generate a pressure based flow of material in a connected channel, where the connected channel has substantially no electroosmotic flow generated. Such pumps have a variety of applications, and are particularly useful in those situations where the application for which the pump is to be used prohibits the application of electric fields to the channel in which fluid flow is desired, or where pressure based flow is particularly desirable.

Abstract: A blood pump intended to be carried by a freely moving patient uses perpendicular magnetic and electrical fields to propel blood. A rod mounted coaxially inside a tube has electrodes in blood contact for establishing a radial electric field, and an inductor having windings parallel to the axis of the tube is used to establish a circumferential magnetic field. To avoid the evolution of gas at the electrode surfaces the magnetic and electric fields are periodically reversed, and the electrodes are made to have very high surface areas. The blood pump is powered by batteries or fuel cells (or a combination of both) to provide long service between recharging and to reduce the weight carried by the patient.

Abstract: An improved magnetorheological fluid pumping system and method are provided which effectively dispense a predetermined amount of magnetorheological fluid for delivery to a MR device such as a damper assembly, for example, during manufacture. The fluid pumping system includes a pump having inlet and outlet valves, a reciprocally mounted piston, a stroke operator device for controlling the movement of the piston and an electronic controller for operating the stroke operator device and the inlet and outlet valves. Importantly, the inlet and outlet valves include an annular flow gap and a magnetic field generating assembly operable in an energized state to generate a magnetic field across the flow gap to cause magnetorheological fluid flowing through the gap to experience a magnetorheological effect sufficient to prevent flow through the gap and in a de-energized state to permit flow through the gap.

Abstract: A microfluidic device operates as a pump for pumping fluid along a channel in a microchip by moving a drive fluid in the channel under the influence of a force field that is generated externally to the channel. The drive fluid is preferably a ferrofluid, and the force field is preferably a variable magnetic field. Drive fluid, driven by variation of the magnetic field, drives driven fluid through the channel. The drive fluid is recirculated, in one case by rotating the drive fluid within an enlargement in the channel, and in another case by returning the drive fluid along a return channel. A valve is formed by using a ferrofluid plug as a movable barrier for fluids in a channel. The microfluid device may be formed between two plates forming a microchip. The channels may be as small as 1 &mgr;m to 100 &mgr;m. Methods of pumping fluids by using an in channel drive fluid and exterior drive are also disclosed.

Abstract: A plasma pumping cell and method for pumping ions from a first region containing a plasma to a second region when the plasma pumping cell is interposed between the first and second regions, the plasma pumping cell including: a partition member (4) positioned between the first and second regions, the partition member (4) having a through opening defining a conduit (22); a plurality of magnets (24) positioned relative to the conduit in a manner to provide lines of magnetic force that extend through the conduit; a source of free electrons in communication with the conduit; and an electric potential source (34) disposed relative to the conduit to create an electrostatic field which accelerates ions from the conduit (22) to the second region.

Abstract: The present invention provides a 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 an apparatus of controlling flow properties of a fluid.

Abstract: A method and apparatus to amplify the magnetic field in an electromagnetic circuit is provided. Amplification factors of several orders of magnitude may be obtained. The system is applicable to a number of different systems, including melt levitation and electromagnetic pumping and propulsion. One embodiment of the invention uses a non-conducting permeable core wound around a dielectric core. An alternating voltage source is connected to a solenoid which is wound around a section of the permeable core. The permeable core has a gap within which a flux concentrating cold crucible is provided. Melt levitation processing takes place within the cold crucible.

Abstract: A duct is provided having a flattened portion containing a liquid slug of gallium, and a magnetic field is passed through the gallium while an alternating current is also passed through the gallium to produce back and forth motion of the liquid gallium slug in step with the alternating current, enabling compression of working fluid within the duct.

Abstract: The present invention generally provides a micropump that utilizes electroosmotic pumping of fluid in one channel or region to generate a pressure based flow of material in a connected channel, where the connected channel has substantially no electroosmotic flow generated. Such pumps have a variety of applications, and are particularly useful in those situations where the application for which the pump is to be used prohibits the application of electric fields to the channel in which fluid flow is desired, or where pressure based flow is particularly desirable.

Abstract: A print array that incorporates reservoir(s), microchannels and electrohydrodynamic (EHD) pumps for selectively dispensing fluid (ink) from the reservoir(s) onto the surface of a receptor.

Abstract: A magnetohydrodynamic (MHD) micropump and microsensor which utilizes micromachining to integrate the electrodes with microchannels and includes a magnet for producing magnetic fields perpendicular to both the electrical current direction and the fluid flow direction. The magnet can also be micromachined and integrated with the micropump using existing technology. The MHD micropump, for example, can generate continuous, reversible flow, with readily controllable flow rates. The flow can be reversed by either reversing the electrical current flow or reversing the magnetic field. By mismatching the electrodes, a swirling vortex flow can be generated for potential mixing applications. No moving parts are necessary and the dead volume is minimal. The micropumps can be placed at any position in a fluidic circuit and a combination of micropumps can generate fluidic plugs and valves.

Abstract: A fluid conduit for flowing electrically conductive fluids includes an elrically conductive pipe, an electrically conductive rod extending axially through the pipe and centrally thereof, a first power source in electrical communication with the pipe and rod, a solenoidal electromagnet disposed around the pipe and a second power source in electrical communication with the electromagnet. Activation of the first and second power sources creates an electric and a magnetic field, respectively, within the pipe which interact and result in a circumferential force in the flow with consequent reduction in wall friction in the pipe.

Abstract: The present invention is directed to a magnetohydrodynamic pump adapted for use in a closed propulsion system. In one embodiment, the magnetohydrodynamic pump includes a duct having a plurality of inlet openings for joining a plurality of streams of liquid into a common single stream and an outlet opening in fluid communication with a nozzle. The magnetohydrodynamic pump includes a pump chamber coupled to a diverging end of the nozzle, and the pump chamber includes a plurality of material output ports. Further, the magnetohydrodynamic pump includes two electrodes mounted on opposite sides of the pump chamber and two mutually attractive superconducting magnets mounted on opposite sides of the pump chambers.

Abstract: The present invention generally provides a micropump that utilizes electroosmotic pumping of fluid in one channel or region to generate a pressure based flow of material in a connected channel, where the connected channel has substantially no electroosmotic flow generated. Such pumps have a variety of applications, and are particularly useful in those situations where the application for which the pump is to be used prohibits the application of electric fields to the channel in which fluid flow is desired, or where pressure based flow is particularly desirable.

Abstract: A method and apparatus to amplify the magnetic field in an electromagnetic circuit is provided. Amplification factors of several orders of magnitude may be obtained. The system is applicable to a number of different systems, including melt levitation and electromagnetic pumping and propulsion. One embodiment of the invention uses a non-conducting permeable core wound around a dielectric core. An alternating voltage source is connected to a solenoid which is wound around a section of the permeable core. The permeable core has a gap within which a flux concentrating cold crucible is provided. Melt levitation processing takes place within the cold crucible. A fluid redirection skirt having an intake port partially surrounds the gap and conducts fluid through an exhaust nozzle.

Abstract: Flat, insulated, metallic strips ("applicators"), are fixed to the wider sides of each permanent magnet assembly in the channel array of a Magnetohydrodynamic (MHD) Vacuum Pump. Electromagnetic power from an external rf/microwave generator is delivered by an appropriate transmission line to each pair of applicators, providing an rf/microwave electric field, generally parallel to the magnetic field of the magnets, across each channel in the array. As the plasma ions and electrons formed by the rf/microwave field lose energy by collisions with the channel surfaces and by collisions with neutral molecules in the channel, the microwave electric field reheats the plasma throughout its passage through the length of the channel array, increasing plasma density and enabling the use of much longer channels, thus increasing the throughput and compression ratio in the MHD Vacuum Pump.

Abstract: An ion drag vacuum pump is installed in a body, one side of which is connected to and in communication with a sealed chamber. An ion generating device and a positive ion dragging device for dragging positive ions generated by the ion generating device to exhaust gases located near the ions by speeding up the ions is disposed in the body. The positive ions are neutralized by a positive ion neutralizing device. The ion generating device includes a corona electrode as a corona discharger to which a positive voltage is applied, a metal plate as a DC glow discharger to which a positive DC voltage is applied, or a first RF electrode and a second RF electrode to which RF power is applied. The ion dragging device includes a target electrode or a first and a second grids to which a positive and a negative voltage are respectively applied. The ion neutralizing device includes a grounded baffle plate.

Abstract: The present invention provides a liquid distribution system, which is useful in a number of contexts, including in accomplishing various synthetic, diagnostic and drug screening reactions. The distribution system can comprise an alpha reservoir and a beta reservoir, a first set of parallel and adjacent first and second feeder channels and a second set of parallel and adjacent third and fourth feeder channels which are offset from the first and second feeder channels, wherein (a) the first and third feeder channels are connected to the alpha reservoir via a first connector channel that is situated above or below the second and fourth feeder channels and are independent of the beta reservoir and (b) the second and fourth feeder channels are connected to the beta reservoir via a second connector channel that is situated above or below the first and third feeder channels and are independent of the alpha reservoir. The distribution system is preferably a microscale distribution system.

Abstract: A method for driving an ionic conductive liquid comprises placing a pair of electrodes in the ionic conductive liquid, and exerting an electromagnetic force to the liquid by application of a voltage between the pair of the electrodes to drive the liquid. A method for mixing and agitating a medium comprises feeding the medium to an ionic conductive liquid, placing a pair of electrodes in the ionic conductive liquid, and exerting an electromagnetic force to the liquid by application of a voltage to drive the liquid and to mix and agitate the medium. An apparatus for delivering a liquid comprises a container for housing an ionic conductive liquid, at least one pair of electrodes in the container, and a power source for applying an voltage between the pair of electrodes, the apparatus delivering the liquid from the container by driving the liquid according to the method for driving.

Abstract: An exhaust apparatus and a high vacuum pumping unit including such high vacuum device and an auxiliary vacuum pump are disclosed, wherein a high vacuum is achieved in a vacuum vessel such that the gas molecules within the vacuum vessel are ionized and accelerated to be exhausted and, further, in the high vacuum pumping unit, those gas molecules diffused back or desorbed from the vacuum pump are ionized and accelerated to be returned to the vacuum pump.

Abstract: A bubble capture electrode configuration for an MHD system includes a body ortion which forms a main channel and holds an electrically conductive fluid adapted to have a first flow direction. The system includes at least two electrodes wherein one is a cathode and the other is an anode. The electrodes are adjacent the body portion and are adapted to transmit an electric current therebetween and through the fluid. An electrolysis reaction is produced adjacent at least one electrode, forming gas bubbles. The system also includes magnetic poles for forming a magnetic field, wherein the magnetic field passes through the fluid substantially transverse to the electric current. Accordingly, a force is created for moving the fluid through the main channel.

Abstract: An apparatus and method for pumping blood using an ion propulsion technique without causing hemolysis. A pulsatile blood pump has transducer for housing a "C" shaped magnet providing a constant magnetic field between the north and south poles of the magnet, a tray slider assembly insertable into a cavity of the transducer, and a disposable insert for insertion into an extracorporeal circuit, the disposable insert comprising a central section having a rectangular outer surface and a constant tubular bore, the central section having a first electric field plate and a second electric field plate disposed on diametrically opposite sides of the outer surface of the central section, the first and second electric field plates being respectively connected to negative and positive terminals of a voltage source for generating an electric field between the first and second electric field plates.

Abstract: Apparatus for capillary electrophoresis having an auxiliary electroosmotic pump. Following a conventional capillary electrophoresis system having a single power supply, a separation capillary, and an optical detector, a conductive membrane connects a second capillary to a second power supply. The second capillary and second power supply act together as an auxiliary electroosmotic pump capable of augmenting or inhibiting the bulk electroosmotic flow in the separation capillary. The apparatus can be used to optimize the stacking profile of the sample and, thus, improve the separation efficiencies for charged solutes.

Abstract: A support structure for clamping the inner coils and inner lamination rings of an inner stator column of an electromagnetic induction pump to prevent damaging vibration. A spine assembly, including a base plate, a center post and a plurality of ribs, serves as the structural frame for the inner stator. Stacked alignment rings provide structure to the lamination rings and locate them concentrically around the spine assembly central axis. The alignment rings are made of a material having a high thermal expansion coefficient to compensate for the lower expansion of the lamination rings and, overall, provide an approximate match to the expansion of the inner flow duct. The net result is that the radial clamping provided by the duct around the stator iron is maintained (approximately) over a range of temperatures and operating conditions.

Abstract: By combining electro-osmotic and electrohydrodynamic pumps in a microchannel, both polar and non-polar fluids can be moved along said channel. The pumps can be made from pairs of wire electrodes inserted into openings in the channel and connected to a source of a pulsed DC power. By reversing the voltages on alternate pairs of pumps, fluid flow can be reversed, thereby acting as a gate or valve. By using digital drivers, for example shift registers that can apply a signal to a switching device connected to an electrode by means of enabling and latch signals to an AND gate, control of flow in individual channels in an array of channels can be had with a high degree of integration, and provide for ready manufacturability.

Abstract: Method and apparatus for flow injection analysis (FIA) using an electroosmotic pump. The apparatus includes: an electroosmotic pump having a grounding joint; a sample injection valve for introducing a sample into a carrier stream which valve is in fluid communication with the grounding joint by way of a conduit; a dispersion coil in fluid communication with the sample injection valve; and a detector which is in fluid communication with the dispersion coil. The grounding joint couples the electroosmotic pumping system and the FIA system but electrically isolates them.Generally, the method utilizes one fluid which is electroosmotically pumped to propel a carrier for flow injection analysis at a controllable flow rate. More specifically, the method includes the steps of: adding a sample to a liquid carrier stream to form a sample zone in the carrier stream; flowing a liquid pumping stream by electroosmosis; and connecting the pumping stream with the carrier stream to propel the carrier stream.

Abstract: An exhaust apparatus and a high vacuum pumping unit including such high vacuum device and an auxiliary vacuum pump are disclosed, wherein a high vacuum is achieved in a vacuum vessel such that the gas molecules within the vacuum vessel are ionized and accelerated to be exhausted and, further, in the high vacuum pumping unit, those gas molecules diffused back or desorbed from the vacuum pump are ionized and accelerated to be returned to the vacuum pump.

Abstract: The electromagnetic machine (1) includes a tubular duct (3 ) intended to receive a conducting material which can circulate in the duct (3) around the core (4) and an inductor (2) arranged coaxially around the duct (3). The inductor (2) includes a magnetic circuit (15) formed by laminated sheet metal combs (18) and windings (14 ) arranged in annular notches (5 ) made in the magnetic circuit (15). The notches (5) are separated from each other by teeth. The teeth of the inductor have lengths in the axial direction which are smaller in the central part of the inductor (2) than in the end parts. The notches (5) are less deep at the ends than in the central part and enclose windings having a smaller number of turns. The windings (14) are each connected to one phase of a polyphase current source.

Abstract: An apparatus is disclosed for the propulsion of water vehicles. A magnet field as well as an electric field with essentially perpendicular field lines are produced in a pipe through which surrounding water flows. In this manner, a force is exercised upon charge carriers within the surrounding water and this force is used as a propulsion force for the water vehicle. The pipe is surrounded by a solenoid coil which is arranged essentially coaxially to the pipe. A first electrode is arranged essentially along the axis of the pipe and a voltage source is switched between the electrode and the pipe, acting as a second electrode. An Archimedes' screw is arranged in the cylindrical gap between the electrode and the pipe in order to deflect the surrounding water circulating about the axis into an axial direction, or the screw is rotationally rigidly connected to a moving conductor arranged perpendicularly to the direction of the magnet field.

Abstract: An electromagnetic pumping assembly (10) for liquid metal is made, which contains an immersible pump section (16) where electromagnetic windings (22) are disposed in the pump section, and an eddy current blocking structure (25) is disposed within the electromagnetic winding (22), providing liquid flow orifices unoccupied by the structure between the eddy current blocking structure and the winding, where there is at least one axial bore (27) through the eddy current blocking structure (25).

Abstract: A ship has an electromagnetic thrust generator including a cylindrical magnet in which there is arranged a helical duct for conducting sea water. The magnet includes a coil housing in which a superconducting coil is disposed. The duct includes an outer wall disposed opposite the internal surface of the coil housing. Electrode members are mounted on inner and outer walls of the duct to create an electrical field across the duct.

Abstract: A submersible, single phase electromagnetic pumping assembly (10) for liquid metal is made, which contains a submersible pump section (16) and a nonsubmersible pump section (18) connected by a hollow conduit (20) where single phase electromagnetic windings (22 and 24) are disposed in each pump section, providing a two stage pumping assembly, and an eddy current blocking electromagnetic winding (22 and 24), providing liquid flow orifices unoccupied by the structure within each pump section near the winding, and where the single phase coils can create a pulsed, standing magnetic wave within each liquid flow orifice.

Abstract: A compressor with no moving parts in the traditional sense having a housing having an inlet end allowing a low pressure fluid to enter and an outlet end allowing a high pressure fluid to exit. Within the compressor housing is at least one compression stage to increase the pressure of the fluid within the housing. The compression stage has a quantity of magnetic powder within the housing, is supported by a screen that allows passage of the fluid, and a coil for selectively providing a magnetic field across the magnetic powder such that when the magnetic field is not present the individual particles of the powder are separated allowing the fluid to flow through the powder and when the magnetic field is present the individual particles of the powder pack together causing the powder mass to expand preventing the fluid from flowing through the powder and causing a pressure pulse to compress the fluid.

Abstract: Stator coils for linear flow electromagnetic induction pumps for pumping liquid metal circulating through a hydraulic system are provided with advantageous deployments of coil power terminals and leads.

Abstract: There is disclosed an apparatus and method for pumping a flowable medium. The pump forces a volume of medium out a pumping chamber by driving an induced plasma arc the length of the pumping chamber from inlet to outlet. An electric potential generated across the medium within the pumping chamber creates the plasma arc near the inlet of the chamber. An induced magnetic field then causes the plasma arc to travel from inlet to outlet thereby forcing the medium ahead of the plasma arc out of the chamber.

Abstract: A converged magnetic flux type electro-magnetic pump in which plural circular conductor plates provided with slits reaching peripheries from central holes in the plates and plural exciting spiral coils are alternately stacked with respect to each other and individually surrounded by magnetic frames. A high density traveling magnetic flux is generated by eddy currents concentrated around the central holes of the circular conductor plates in response to the application of a multiphase alternating voltage in a non-magnetic pipe passing through the central holes with a cylindrical iron core inserted in the pipe, so as to convey high temperature molten metal such as molten sodium used for refrigerating a high speed breeder reactor. The thickness of the central portions of the circular conductor plates is greater than the remainder of the plates, so as to form a radial T-shaped cross-section.

Abstract: An electromagnetic induction pump in which an electrically conductive liquid is made to flow by means of a force created by interaction of a permanent magnetic field and a DC current. The pump achieves high efficiency through combination of: powerful permanent magnet materials which provide a high strength field that is uniform and constant; steel tubing formed into a coil which is constructed to carry conducting liquids with minimal electrical resistance and heat; and application of a voltage to induce a DC current which continuously produces a force in the direction of the desired flow.

Abstract: The invention is directed to a device for pumping electro-rheological flu comprising a casing that defines an inner rotor chamber having a central inlet opening and a peripheral discharge opening. Rotatably disposed within said chamber is a rotor for imparting energy to the pumped electro-rheological fluid comprising of a plurality of non-conducting coaxial substantially parallel spaced disks. On one face of each disk are embedded one or more electrodes and on the opposing face of each disk are attached one or more conductive surfaces. By selectively applying an electric charge to the embedded electrodes, an electric field is produced between the electrodes and the conducting surfaces of adjacent disks. As a result, the viscosity of the electro-rheological fluid exposed to the applied electric field is increased thereby producing electro-rheological fluid vanes between adjacent disks.

Abstract: Apparatus for repeated automatic execution of a thermal cycle for the treatment of a sample, especially a biological sample, comprises means (6) defining a pathway which is physically closed throughout the treatment and within which the sample is resident throughout the treatment. Means (3, 4, 11, 12) are provided to move the sample between different positions along the pathway and (7, 15, 16) to heat or cool the sample as a function of its position within the pathway. Preferably the pathway is a capillary tube, which may be in spiral, closed loop or linear form. Heating and cooling means are provided by thermostated zones which may provide a continuous thermal gradient regular or irregular, or be in a discontinuous arrangement. The preferred means of moving the samples is magnetic.