Artificial muscle is defined herein as a blend of a hydrogel and a redox polymer, which dramatically swells and shrinks under environmental stimuli. This actuator can be applied to micro fabricating valves for controlled delivery systems. Previous work in our group has shown that a blend of poly(2- hydroxy ethyl)methacrylate (polyHEMA) and polyaniline displayed significant swelling and shrinking upon application of an electrochemical bias. In this type of artificial muscle, polyaniline, a redox polymer, acts as the 'electronic backbone' for transferring for most of the swelling and shrinking. However, polyHEMA showed only weak swelling an shrinking in a chemimechanical system, thus purpose of the current study is to enhance the artificial muscle actuating properties. An optimized hydrogel swelled up to 1000 percent in alkaline solution and contracted 70 percent in acid solution. An artificial muscle microvalve array was also micro fabricated and tested. These results could lead to a smart wireless drug delivery implanted system.

Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which are designed to detect only one physical or (bio-)chemical parameter. In the present work, an ISFET (ion-sensitive field-effect transistor), which is well known as a (bio-)chemical sensor, is utilised for the flow velocity and flow direction measurement for the first time. The proposed flow sensor presents a chemical sensor-actuator system and consists of a H+-ion generator and a pH ISFET that detects the in-situ electrochemically generated H+ ions. By measuring the time of flight, the flow velocity can be determined. Since this measuring method represents a dynamic method, a calibration of the sensor usually is not required, because only relative changes in the sensor output signal are of interest. Moreover, sensor+s drift, temperature instability and sensitivity discrepancy between the various ISFETs are not relevant. The experimental results show good linearity between the measured flow velocity with the ISFET and the delivered flow rate of the pump. Due to the fast response of the ISFET (usually in the millisecond range), an ISFET-based flow sensor is suitable for the measurement of the flow velocity in a wide range. The results of the flow direction measurement with two ISFETs are presented, too.

This paper presents a method for creating planar, fluidic devices by bonding together laminations created with the nickel electroforming method. The fluid amplifier is created by sandwiching together several, several .001 inch [25.4 microns] thick laminations. These laminations contain the fluid amplifier, vents and transfer channels. The laminations are initially coated with an adhesive, which acts as a bonding agent when subjected to heat. Special pins are used to insure proper alignment. The entire process is performed in a clean room environment to minimize problems. The proportional fluid amplifier is made bi-stable by introducing positive feedback.

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.

A methodology for the simulation of a reciprocating displacement micro-pump is presented. First a check valve model was analyzed using coupled FEM to obtain the characteristics relationship between flow rate and the pressure as well as the minimum valve opening pressure. Then a model for the micro-pump actuator driven by PZT disks is proposed and simulated. The pump model takes into account the effects of chamber pressure and geometrical parameters. The maximum downward deflection of the actuating membrane is taken as the target parameter to analyze. It was found that the maximum membrane deflection could reach over 10micrometers microns, much larger than the radial displacement. This 'displacement amplification' is the underlying working principle of this kind of micro-pump. Quantitative analyses of the effects of various factors on the deflection are conducted. It is found that the thickness of the membrane has the biggest influence on the deflection. For each membrane thickness, there exists an op[t9kum PZT disk thickness that gives the maximum deflection at a particular electric field. Other factors with less influence on the deflection are also investigated. An optimum set of design parameters for the micro-pump is obtained form the analyses.

A 3D model of one type of micro pumps was supposed and analyzed using finite element method (FEM). The pump had square shape cavity and was driven by a square shape PZT component. The finite element analysis (FEA) took into consideration of the effects of PZT component dimensions, membrane thickness, pump chamber pressure and other geometric parameters. Modal analyses were also conducted. Compression ratio of the pump chamber was taken as the prime parameter for the analyses. It was found that the membrane thickness and the PZT plate thickness played major roles in determining the compression ratio. For each membrane thickness, there was always an optimum PZT plate thickness that gave the maximum compression ratio. Curves showing the relationship between the optimum PZT plate thickness and the membrane thickness at different chamber pressures were given, based on the FEA results. A set of optimum pump design parameters was proposed.

A dynamic model for a PZT actuated valveless micropump is presented in this work. The model couples PZT actuation with fluid flow in a flow chamber. Extended Bernoulli equation is used to describe flow dynamics in the inlet and outlet of the micropump. The dependence of the output pressure and flow rate on pump parameters is discussed. For low frequency actuation, the flow rate and back pressure increase as the PZT membrane thickness increases. The flow rate also increases for larger nozzle neck. The back pressure increases as the nozzle neck enlarges, reaches a maximum at about 80 microns, and then decreases when the nozzle neck keeps increasing. Such dependence becomes insignificant for nozzle neck larger than 200 microns. This model also predicts that the neck length has little influence on the back pressure and flow rate.

This paper describes ongoing work in the development of microreactor-based systems for applications in the chemical process industry. The microreactors discussed here are formed from silicon using robust micromachining processes to produce devices with micrometer-scale fluidic structures including passageways for the introduction and removal of gases, and a reaction zone with a thin-film catalyst. We describe experiments done to characterize these reactors for use as development tools for industrial catalytic processes in terms of catalyst screening, acquisition of rate laws, and determination of optimal process conditions. The system studied here, the reaction of a cyclic olefin (cyclohexene) with hydrogen in the presence of platinum catalyst, is a model for industrially important catalytic hydrogenation and dehydrogenation reactions.

Researchers at Lawrence Livermore National Laboratory are developing means to collect and identify fluid-based biological pathogens in the forms of proteins, viruses, and bacteria. To support detection instruments, we are developing a flexible fluidic sample preparation unit. The overall goal of this Microfluidic Module is to input a fluid sample, containing background particulates and potentially target compounds, and deliver a processed sample for detection. We are developing techniques for sample purification, mixing, and filtration that would be useful to many applications including immunologic and nucleic acid assays. Many of these fluidic functions are accomplished with acoustic radiation pressure or dielectrophoresis. We are integrating these technologies into packaged systems with pumps and valves to control fluid flow through the fluidic circuit.

The goal of this study is to determine the feasibility of high-resolution separation of oligonucleotides in microchannels. High-resolution separation of oligos is extremely challenging because it depends on sequence-specific migration. Also, it requires high viscosity gels, an excess field of 500 V/cm, and long separation columns between 2 to 3 cm. An improved composition of low and high molecular weight of PDMA, high electric field (550 V/cm) and longer separation columns (30 mm) were used to separate cy5 labeled poly(dT). We were able to achieve single base resolution of poly(dT), between 25 and 31 bases, in less than 40 seconds; and the number of theoretical plates was found to be around 2.7 X 105. In addition, we investigated the mobility of cy5 labeled poly(dA), poly(dC) and poly(dT) in 3 percent PDMA. We found that the differential mobility of nucleotides is very small and increases in the following order: G, T, C, and A. The difference in mobility between these bases is found to be about 1 percent between A and C, and 0.1 percent between C and T. However, we found that various buffer modifications helped in increasing the differential mobility between bases and hence the resolution of separated species. This work was done on a glass microchip with a separation column 12 um deep, 30 um wide and 30 mm long.

With the increasing rate of discovery of new potential pharmaceuticals, an accurate high throughput screening method is needed to provide toxicology and pharmcology profiles of chemicals. This can be done using a cell culture analog device which uses interconnected tissue cultures to represent different organ systems in animals. A working prototype of microscale cell culture analog (CCA) device has been constructed. Cells cultured in the system have been shown to be viable for more than 24 hours. In this paper, we will present the development of this microscale CCA device as well as the integratable micropump we have created to produce the recirculating flow.

A new micro-channel protein separation device, which is easy to separate proteins from a mixture and includes an in-situ protein detection set up, has been fabricated. An example of separating two proteins from a mixture within 15 min using a low electric field of 20 V/cm is demonstrated. The separated protein was confirmed by the staining method and electron spectroscopy for chemical analysis (ESCA). This device is potentially applicable to the separation of a wide range of biomolecules.

Progress in sequencing the human genome and the DNA of other organisms is providing many opportunities for creating powerful systems for numerous and diverse applications in DNA testing. These systems and the chemical processes, such as PCR, which they are designed to carry out, have recently made great strides in miniaturization through advances in micro-fluidics and micro-optics. In addition, new techniques in biological processing, such as controlled ultrasonic lysis, are being applied to small, automated, integrated instruments designed to provide important DNA results in a timely and routine manner. These systems are bringing DNA identification out of the laboratory and into our daily lives. Instead of waiting for days or weeks for a result, we will have them in minutes. Instead of relying on the skills of molecular biologists, the average person will be able to run a DNA test. These new advances will widely impact many aspects of our medical practices, food processing, and public safety.

With the growing interest and development of microfluidic systems, the need for micro-scale laminar flow mixing techniques is evident. Traditional mixing methods often rely upon turbulent flow for mixing which is generally not present on the micro-scale and so alternative approaches must be sought. In this work we investigate the potential for destabilizing the interface between converging flows using flow pulsation. A 3-D computational model of the converging flow at a 90 degrees junction is developed using the Fluent CFD software whereby the time-dependent behavior of the interface can be studied downstream of the junction. The interface is tracked using the Volume-of-Fluid method. Our results show the formation of a complex, evolving interfacial distortion which propagates and persists downstream of the junction; the degree of distortion observed suggests the possible onset of a hydrodynamic instability. The results also show that the complexity of the interfacial structure is only significant at higher frequencies (order of kHz) which is appropriate for MEMS pumping devices.

Fluid flow and heat transfer characteristics of single-phase flows in microchannels for refrigerant R-134a were experimentally investigated. Experiments were conducted using rectangular channels micro-milled in aluminum with hydraulic diameters ranging from approximately 112-mm to 210-mm and aspect ratios that varied from 1.0 to 1.5. Using overall temperature, flow rate, and pressure drop measurements, friction factors and convective heat transfer coefficients were experimentally determined for steady flow conditions. Reynolds number, relative roughness, and channel aspect ratio were the parameters examined in predicting friction factor and Nusselt number for the experiments. Experiment results indicated transition from laminar to turbulent flow occurred between a Reynolds number of 2,000-4,000. Friction factor results were consistently lower than values predicted by macroscale correlations. Nusselt number results indicated channel size may suppress turbulent convective heat transfer. Results also indicate that surface roughness may affect heat transfer characteristics in the turbulent regime.

In this paper, an electrochemical actuator was fabricated and tested. The good linearity relationship between the dosing rate and the electrolysis current has been achieved for the demonstrative electrochemical actuator in the selected electrolyte and electrode material cell from 50 micro-A to 1000 micro-A electrolysis current. The microflow rate less than the evaporation that can be obtained by an improved standard gravimetric method in situ. The error resulted from tested work liquid inevitable evaporation was also excluded by the improved approach at very low microflow testing. The on-line testing method can be used as very low microflow rate calibration. The lowest stable flow rate was 0.19 micro-liter/min (3.2nl/s). The response time was also shown by the means of on-line measurement.

In the last decade, examples of devices manufactured with SUMMiT(TM) technology have demonstrated the capabilities of polysilicon surface micromachining. Currently we are working on enhancements to this technology that utilize additional structural layers of silicon nitride to enable Microfluidics and BioMEMS applications. The addition of the silicon nitride layers allows the fabrication of microfluidic flow channels that are transparent (allowing observation of cellular motion) and insulating (allowing the placement of polysilicon electrodes at arbitrary locations in the flow channels). The goal of this technology development effort is to ultimately provide functionality that is not feasible with other microfabrication technologies. The enhancements build on the key features of surface micromachining: manufacturability and compatibility with CMOS processing, which allow us to leverage the investment already made in the microelectronics processing technology. In this paper we will present examples of devices fabricated using this new enhanced surface micromachining technology. These devices include pumps, valves, and a cell manipulator.

The electro-static self-assembly process, or ESA, has proved to be extremely successful in creating multi-layer coatings with properties that can be optimized for particular applications. In this process, almost any surface with charged functional groups can be used as a substrate. Sequential dipping in solutions having ions of opposite charge builds up the layers through ionic bonding. Multi- functional bio-compatible coatings on MEMS deices intended for use in-vivo could be formed using ESA. In this paper, we describe two different models of the process based on adaptive computational techniques using cellular automata. The output of the models consists of three parameters as a function of layer: layer coverage, total average coating height and layer roughness. The result of the models are compared to experimental data to determine which of them more accurately mirrors the ESA process.

The present work extends the concept of microcantilever (MC) based transducers to hybrid MEMS that integrate actuation and multiple sensing modes. Theoretical models predict significant limitations for the mechanical energy produced due to molecular interactions of conventional MCs with the environment. In order to overcome these limitations, we focus on cantilever designs and technologies of nanostructured coatings that are more compatible with fluidic MEMS and provide highly efficient molecular-driven actuation as well as additional modes of selectivity. In particular, co-evaporated Au:Ag films were used to prepare nanostructured interfaces that strongly enhance both chemi-mechanical transduction and Raman scattering. Acquisition of surface enhanced Raman scattering (SERS) signals generated on the cantilevers with nanostructured gold coatings provided highly specific molecular information. Additionally, highly efficient, environmentally-responsive sensor-actuator hybrids were created using MCs made of epoxy based photoresist SU-8 that were modified with hydrogel. Immobilization of colloidal silver particles in the acrylate based hydrogels provides multi-modal functionality for these MCs. Using several alternative technologies, we have created MC transducers that exhibit micrometer scale deflections in response to changes in molecular microenvironment and provide vibrational signatures of constituents in that environment. It is anticipated that these molecular-actuated MC transducers will constitute a novel platform for future biomedical devices.

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.

In photomedicine in some of cases radiation delivery to local zones through optical fibers can be changed for the direct placing of tiny optical sources like micro lasers or LED in required zones of ears, nostrils, larynx, nasopharynx cochlea or alimentary tract. Our study focuses on the creation of optoelectronic microdevices for local photo therapy. Now, they are taking pre-clinical trials in stomatology to treat inflammatory processes in the mouth cavity, in otolaryngology to treat otitis and for treatment of the gastro-intestinal tract. This paper is more emphasized on development optical microdevices for phototherapy of the gastro-intestinal tract. The influence of radiation from phototherapetic micromodules on composition of intestinal microflroa and the immunologic inspection of patients with dysbacteriosis of the intestine as a result of diseases of the gastrointestinal tract and after antibacterial therapy for other disturbances are studied. The obtained result are comparable with indices of the control group. At the same time, it should be noted that stimulation of growth of natural flora is recorded in the main group of patients which inhibits the activity of conditioned pathogenic microflora.

Applications of microfluidics and MEMS (micro-electromechanical systems) technology are emerging in many areas of biological and life sciences. Non-contact microdispensing systems for accurate, high-throughput deposition of bioactive fluids can be an enabling technology for these applications. In addition to bioactive fluid dispensing, ink-jet based microdispensing allows integration of features (electronic, photonic, sensing, structural, etc.) that are not possible, or very difficult, with traditional photolithographic-based MEMS fabrication methods.Our single fluid and mutlifluid (MatrixJetT) piezoelectric microdispensers have been used for spot synthesis of peptides, production of microspheres to deliver drugs/biological materials, microprinting of biodegradable polymers for cell proliferation in tissue engineering requirements, and spot deposition for DNA, diagnostic immunoassay, antibody and protein arrays. We have created optical elements, sensors, and electrical interconnects by microdeposition of polymers and metal alloys. We have also demonstrated the integration of a reverse phase microcolumn within a piezoelectric dispenser for use in the fractionation of peptides for mass spectrometer analysis.

The technique of micro arraying involves laying down genetic elements onto a solid substrate for DNA analysis on a massively parallel scale. A pin-based robotic platform for bioMEMS is used to prepare microarrays by transferring liquid samples from microtitre plates to array pattern son the surface of coated glass slides. The liquid dries to form spots diameter < 200 micrometers . This paper present the design and performance of reservoir pins with particular emphasis on microfluidics and the influence of pin geometry and surface topology. In the newly developed manufacturing process a pin is produced by (a) wet etching of tungsten wire, followed by (b) micromachining with a focused laser to produce a capillary channel structure and a microreservoir. The pin has a flat end 100 micrometers in diameter from which a 600 micrometers long capillary channel, 15 micrometers wide leads up the pin to a reservoir. The pin capacity is 50 nanolitres of fluid containing DNA, and at least 5-0 spots can be printed before replenishing the reservoir. A typical robot holds 16- 48 pins. Scanning electron micrographs of the metal surfaces show roughness on the scale of 5 micrometers . However, the pins give consistent and reproducible spotting performance. In this paper comparisons will be made between the real life performance of the pins on the robotic platform with observations and measurements made using a video microscope system, and an assessment of the prospects for bioMEMS and further miniaturization of this technology.

The thermal control of future micro/nano spacecraft will be challenging due to power densities which are expected to exceed 25 W/cm2. Advanced thermal control concepts and technologies are essential to keep their payload within allowable temperature limits and also to provide accurate temperature control required by the science instruments and engineering equipment on board. To this end, a MEMS-based pumped liquid cooling system is being investigated at the Jet Propulsion Laboratory (JPL). The mechanically pumped cooling system consists of a working fluid circulated through microchannels by a micropump. Microchannel heat exchangers have been designed and fabricated in silicon at JPL and currently are being tested for hydraulic and thermal performance in simulated microspacecraft heat loads using deionized water as the working fluid. The microchannels are 50 microns deep with widths ranging from 50 to 100 microns. The hydraulic and thermal test data was used for numerical model validation. Optimization studies are being conducted using these numerical models on various microchannel configurations, working fluids, and micropump technologies. This paper presents background on the need for pumped liquid cooling systems for future micro/nano spacecraft and results from this ongoing numerical and experimental investigation.

In this paper we present embossing tools that were fabricated using both UV and X-ray lithography. The embossing tools created were used to emboss microfluidic channels for bioanalytical applications. Specifically, two tools were fabricated. One, using x-ray lithography, was fabricated for electrophoretic separations of DNA restriction fragment analysis. A second tool, fabricated using SU8, was designed for micro PCR applications. Depths of both tools were approximately 100 micrometers . Both tools were made by directly electroforming nickel on a stainless steel base. Fabrication time for the tool fabricated using x-ray lithography was less than 1 week, and largely depended on the availability of the x-ray source. The SU8 embossing tool was fabricated in less than 24 hours. The resulting nickel electroforms from both processes were extremely robust and did not fail under embossing conditions required for PMMA and/or polycarbonate. Some problems removing SU8 after electroforming were sen for smaller size gaps between nickel structures.

A high-speed Ta-Si-N gas microvalve has been designed, fabricated and characterized. Ta-Si-N has a unique combination of electrical and mechanical properties suitable for robust high performance MEMS devices. The valve reported here represents the first working MEMS device integrating a sputtered Ta-Si-N layer, for use at differential pressures greater than 2 bar and capable of achieving controlled flow-rates under pulse width modulation (PWM). Previously reported, electrostatically actuated microvalves (3,4,5) were limited to operating pressures less than 200 mbar, and their switching behavior was not studied. The valve is based on a surface micromachined Ta-Si-N membrane that closes a deep reactive ion etched hole. The valve was optimized to achieve a low actuation voltage and fast commutation. This study focuses on the characterization of the switching behavior of the valve membrane and its influence on the flow-rate.

We have used an embossed plastic microfluidic system for the electrophoretic separation of relatively small molecules followed by electro spray ionization of the analytes. Th separation of dyes has been also visualized in microfluidic systems. A lithographically produced silicon master was used to emboss channels in ZEONOR 1020R plastic. An oxygen plasma was used to convert the plastic channel surface from hydrophobic to hydrophilic characteristics for the separation of molecules in aqueous solution.

Multidisciplinary efforts, combining microfabrication, chemistry and molecular biology, have been recently focused on the development of large electrode arrays loaded with oligonucleotide probe to allow rapid analysis of nucleic acid samples. Different micromachining techniques can be used for obtaining the inlet, outlet and main reservoirs for the analyte. In the present work silicon wafers are used as substrates for the microarrays, patterned by means of direct writing or optical lithography. Three methods are developed in order to obtain reservoirs with depths ranging from 5 microns to 200 microns, allowing an analyte volume in the range of 1 nl to 1 ml: reactive ion etching of a polyimide layer, wet anisotropic etching of silicon, respectively deep wet isotropic etching of the glass cover. The glass cover is bonded at low temperature, using spin-on glass as adhesive and ensures a protection of the analyte, as well as a rapid entering of the analyte in the reservoirs, increasing thus the speed of the analysis. A custom laser induced fluorescence set-up is used in order to perform the analysis. The fluorescent DNA molecules are concentrated and localized during an observation time of 60 seconds, proving the functionality of the device.

The product distribution of fast-competitive reactions is a function of the speed at which the mixing of the two reactants occurs. Micro-fluidic mixers (micromixers) are touted as one area that micro-fluidic devices have fundamental advantages over traditional chemical processing equipment. Micromixers must demonstrate a significant advantage over the best current processing equipment if micromixers are to be implemented in current applications by the very conservative chemical industry. In this study, the mixing performance of a small diameter mixing tee was compared to the mixing performance of a commercial static mixer. In both studies, the hydrolysis of dimethoxypropane was measured quantitatively using gas chromatography. To date, a 177 micron mixing tee and 254 micron mixing tee have been tested and compared with a 1/4 inch and 1/8 inch commercial static mixer. At constant Reynolds numbers, the 254 micron micro-mixer is superior to the 1/4 inch static mixer and the 177 micron micro-mixer is superior to the 1/8 inch static mixer. Reynolds numbers of only 1180 and 410 have been obtained for the 254 micron and 177 micron mixing tee to date. Changes are being implemented to allow operation of higher Reynolds numbers with even smaller diameter mixing tees fabricated from silicon.

Technological interest in microfluidic systems have been increased day by day. This paper scans the microfluidic technology for modeling, simulation, and fabrication processes. The advantages of polymers for microfluidic devices over common MEMS processing of glass and silicon are becoming increasingly important. This is due to the biocompatible polymer surfaces, low cost production, and availability of different material properties and chemistry. Hot-embossing technology for high aspect ratio structures as well as polymer nanoimprinting for low cost manufacturing MEMS process are discussed.

Polymerase chain reaction (PCR) is a well-described method for selective identical replication of DNA molecules. In recent years, many micromachined PCR chips have been reported. These miniaturized PCR chips have great advantages such as a significant reduction in reagent costs and vastly reduced reaction time over the conventional PCR devices. In this paper a micro analysis system that will allow submicro-liter scale, continuous-flow PCR to be conducted in a glass chip has been presented. This glass chip is achieved through thermally bonding two pyrex 7740 glass wafers. One pyrex wafer is etched to form a 20-cycle microchannel of 80 micron wide and 30 micron deep. The other pyrex wafer with microheaters is thermally bonded to the microchannel wafer to produce a closed continuous microchannel for PCR. The total length of the microchannel is 0.5 m. The size of this device is 56 mm 'e 24 mm 'e 1 mm. Three reaction temperatures are controlled by three PID controllers. This PCR chip has a significant reagent reduction with a volume of less than 1 micro-liter. With 1 micro-liter reagent, we get total reaction time of 0.5 min to 3 min depending on various flow rates. This analysis chip is fabricated using standard micromachining techniques. The advantages of this chip include small quantities of reagent needed, high throughput, rapid thermal cycling, and batch micro-fabrication resulting in a significant cost reduction.

The majority of micropumps developed result in pressure differences of less than about 3 mH2O. In this work, a vacuum micropump with cascaded chambers is proposed; it is composed of two layers of reciprocal actuated membranes and two layers of check valves. Design of the vacuum micropump with electrostatic and piezoelectric actuators as well as cantilever check valves is proposed. The selection of actuation modes and actuation valves is addressed. Two theoretical design functions are derived to calculate the maximum attainable vacuum with the operation rounds of the membranes and the cascaded stage number. The analyses suggest that large membrane displacement, small dead volume of the chamber, and small backward leakage rate are preferred in obtaining higher vacuum. The increase of chamber stage numbers results in an exponential increase of the vacuum. The relationship between the vacuum and operation rounds is also similar to that between the vacuum and stage numbers: the more rounds the vacuum micropump is operated for, the higher the vacuum is obtained. The designed vacuum micropump can be integrated into the current IC techniques with batch production and high pumping ability.