Micropump

We present a laterally emitting, coupled cavity micro fluidic dye ring laser, suitable for integration into lab-on-a-chip micro systems. The micro-fluidic laser has been successfully designed, fabricated, characterized and modelled. The resonator is formed by a micro-fluidic channel bounded by two isosceles triangle mirrors. The micro-fluidic laser structure is defined using photo lithography in 10 microns thick SU-8 polymer on a glass substrate. The micro fluidic channel is sealed by a glass lid, using PMMA adhesive bonding. The laser is characterized using the laser dye Rhodamine 6G dissolved in ethanol or ethylene glycol as the active gain medium, which is pumped through the micro-fluidic channel and laser resonator. The dye laser is optically pumped normal to the chip plane at 532 nm by a pulsed, frequency doubled Nd:YAG laser and lasing is observed with a threshold pump pulse energy flux of around 55 micro-Joule/square-milimeter. The lasing is multi-mode, and the laser has switchable output coupling into an integrated polymer planar waveguide. Tuning of the lasing wavelength is feasible by changing the dye/solvent properties.

Lab on Chip technologies have enabled the possibility of novel μTAS devices (micro Total Analysis System) that could drastically improve health care services for billions of people around the world. However, serious drawbacks that reside in fluid handling technology currently available for these systems often restrict the commercialization of such devices. This work demonstrates a novel fluid handling method as a possible alternative to current micropumping techniques for disposable microfluidic chips. This technology is based on a single use, low cost, thermal micropumping system in which expandable microsphere mixtures are activated by commercial grade laser diodes to achieve flow rates as high as 2.2 μl/s and total volumes over 160 μl. With the addition of a volume dependent shut off valve, nanoliter repeatability is realized. Pressure and heat transfer related data are presented. Finally, the possible prospects and limitations of this technology as a core element in unified optofluidic systems are discussed.

Microfluidics is a promising technology that is increasingly attracting the attention of researchers due to its high efficiency and low-cost features. Micropumps, micromixers, and microvalves have been widely applied in various biomedical applications due to their compact size and precise dosage controllability. Nevertheless, despite the vast amount of research reported in this research area, the ability to implement these devices in portable and implantable applications is still limited. To date, such devices are constricted to the use of wires, or on-board power supplies, such as batteries. This thesis presents novel techniques that allow wireless control of passive microfluidic devices using an external radiofrequency magnetic field utilizing thermopneumatic principle. Three microfluidic devices are designed and developed to perform within the range of implantable drug-delivery devices. To demonstrate the wireless control of microfluidic devices, a wireless implantable thermopneumatic micropump is presented. Thermopneumatic pumping with a maximum flow rate of 2.86 μL/min is realized using a planar wirelessly-controlled passive inductor-capacitor heater. Then, this principle was extended in order to demonstrate the selective wireless control of multiple passive heaters. A passive wirelessly-controlled thermopneumatic zigzag micromixer is developed as a mean of a multiple drug delivery device. A maximum mixing efficiency of 96.1% is achieved by selectively activating two passive wireless planar inductor-capacitor heaters that have different resonant frequency values. To eliminate the heat associated with aforementioned wireless devices, a wireless piezoelectric normally-closed microvalve for drug delivery applications is developed. A piezoelectric diaphragm is operated wirelessly using the wireless power that is transferred from an external magnetic field. Valving is achieved with a percentage error as low as 3.11% in a 3 days long-term functionality test. The developed devices present a promising implementation of the reported wireless actuation principles in various portable and implantable biomedical applications, such as drug delivery, analytical assays, and cell lysis devices.

The objective of the study described here is to explore the possibilities of an innovative two-stage micro pump. The first stage was realized by a micro Rotary Shaft Pump (RSP) with an external diameter of 3mm and a blade height of 0.4mm. The second stage, partially integrated in the RSP, was a centrifugal
viscous pump with a 4.4mm external diameter. The numerical and experimental characteristics of two prototypes are presented. Different rotational speeds were tested up to 24,000 rpm, obtaining pressure increases up to 12 kPa and flow rates up to 150 ml/min, corresponding to a head coefficient of 0.12 and a flow coefficient of 0.4. 3D time dependent CFD simulation were also carried out and compared
with experimental data. Numerical results allowed to study the flow field inside the pumps and to compute the hydraulic efficiency of the two stages, as well as, to show the distribution of losses inside the pumps.

This paper reports a novel, wirelessly powered micropump based on thermo-pneumatic actuation using a frequency-controlled heater. The micropump operates wirelessly through the energy transfer to a frequency-dependent heater, which was placed underneath the heating chamber of the pump. Heat is generated at the wireless heater when the external magnetic field is tuned to the resonant frequency of the heater. The enclosed air in the chamber expands and forces the liquid to flow out from the reservoir. The developed device is able to pump a total volume of 4 ml in a single stroke when the external field frequency is tuned to the resonant frequency of the heater at the output power of 0.22 W. Multiple strokes pumping are feasible to be performed with the volume variation of ∼2.8% between each stroke. Flow rate performance of the micropump ranges from 1.01 μL/min to 5.24 μL/min by manipulating the heating power from 0.07 W to 0.89 W. In addition, numerical simulation was performed to study the influence of the heat transfer to the sample liquid. The presented micropump exclusively offers a promising solution in biomedical implantation devices due to its remotely powered functionality, free from bubble trapping and biocompatible feature.

This paper presents an approach to the construction and measurements of electrodynamic and reluctance actuators. Executive elements were used as drives in a novel concept of a magnetomotive micropump. The paper discusses various aspects concerning the designation of parameters, control system, the explanation of physical phenomena, and the optimization of the basic elements for coil units. The conducted work describes the measurement system and the analysis of the derived values. The actuators were compared and the pros/cons of building the conceptual device were highlighted. The best solution to be used in the upcoming work concerning the construction of a magnetomotive micropump was chosen based on measurements, engineering aspects, layout control, and key parameters such as the piston velocity, energy stored in capacitors, and efficiencies.

An electrostatic micromachined pump is designed and simulated. The designed micropump has the advantages of flow rate controllability, self-priming, small chip size, and low power consumption. The designed micropump is simulated by the Runge-Kutta method. The flow rate of the designed micropump is considered 10 µl/min which is quite suitable for drug delivery applications, such as chemotherapy. The simulation results for the first membrane deflection with different materials and at pulsed applied voltage is introduced.

A rotating cylinder asymmetrically placed across a duct, with its axis perpendicular to the axis of the channel, has long established itself as a simple mechanism for the transport of Newtonian fluids in microfluidic channels. In the present study, the possibility of transporting viscoelastic fluids by this simple mechanism is numerically investigated using finite-volume method (FVM). For ease of analysis, we have relied on two-dimensional flow between two parallel plates for this purpose. To screen out the complicating effects of shear-dependent viscosity from the analysis, the viscoelastic fluid of interest is assumed to obey the Oldroyd-B model. Using finite-volume-method (RheoFoam solver) we have obtained converged creeping-flow results over a wide range of working parameters for Deborah numbers up to unity. Based on our obtained numerical results, it is concluded that a fluid's elasticity can negatively affect the performance of viscous micro-pumps. The drop in efficiency is predicted to increase the larger the Deborah number. At De = 1, the drop in efficiency is predicted to be around 30%, as compared with Newtonian fluids of the same viscosity. Since the drop in efficiency is not too excessive, viscous micropumps can be regarded as a viable option for the transport of moderately-elastic liquids, particularly in those microfluidic applications where efficiency is of secondary importance.

Micro total analysis systems (μTAS) have been developed to perform a number of analytical processes involving chemical reactions, separation and sensing on a single chip. In medical and biomedical applications, μTAS must be designed considering special transport ...

Among the main benefits of microsystem technology are its contributions to cost reductio, reliability and improved performance. however, the packaging of microsystems, and particularly microsensor, has proven to be one of the biggest limitations to their ...

A 2-dimensional model is developed to investigate fluid flow in a magneto-hydrodynamic (MHD) micropump. The transient, laminar, incompressible, and developing flow equations are numerically solved using the finite difference method and the SIMPLE algorithm. The micropump is driven using the Lorentz force, which is induced as a result of interaction between an applied electric field and a perpendicular magnetic field. The effect of Hartmann number on the transient velocity profile and the entrance region length is studied. It is found that controlling the electrical conductivity and magnetic flux density will allow controlling the entrance region length.

Micro-fabricated diaphragms can be used to provide pumping action in microvalve and microfluidic applications. In this paper, a design for a micro-diaphragm that features low power and small area is presented. The diaphragm is actuated using a Surface Acoustic Wave (SAW) ...

Micropumps are used extensively in biomedical field and are finding its way to other areas. Development in micropumping technology is necessary, in a time where electronics is moving towards the nano scale and its conventional cooling is useless, and where the biomedical science is opting for less insidious surgical procedures and more precise drug delivery methods.
In this paper, 3D model of a micro electromagnetic pump was created and its electromagnetic and mechanical analysis was performed. The parts of the conventional micropump were replaced with compatible MEMS materials and analysed. A 3D model of pump’s diaphragm was also created using Ansys and its mechanical analysis was done with the various electromagnetic forces obtained from the electromagnetic analysis. These analysis were done with first the diaphragm material as Polyimide and then as PDMS. Comparisons were also performed with diaphragm deflection corresponding to the various micropump configurations taken.

Multi-pumping flow systems (MPFS) are one of the most recent developments in terms of the design, conception and implementation of continuous flow methodologies, for sample and reagent handling and for the automation of analytical procedures. Based on the utilisation of multiple solenoid micro-pumps they enable the configuring of fully automated and easily controlled and operated analytical systems since all the fundamental operations involved in carrying out a sample analysis, including sample insertion, reagent addition and signal measurement could be carried out by the same manifold component, reducing the number of system parts and minimising its control or the occurrence of mal-functions. On the other hand, micro-pumps actuation produce a pulsed flow characterised by a chaotic movement of the solutions, which contributes to a fast sample/reagent homogenisation with low axial dispersion yielding improved analytical signals. The combination of such advantageous features resulted ...

A novel flow system for the spectrophotometric determination of dipyrone with p-dimethylaminobenzaldehyde exploiting the multi-pumping approach was developed. The proposed methodology utilises several micro-pumps for propelling the involved fluids under improved mixing conditions, introducing sample/reagent aliquots and providing commuting facilities. As a consequence the multi-pumping system presents high versatility and manifold simplicity, as well as a straightforward operational control and enhanced analytical capabilities. Linearity of the analytical curve was observed within 10 and 400 mg l−1 dipyrone (r=0.9997; n=6), results were precise (r.s.d.<0.12%; n=20) and sampling rate was 50 h−1. Detection limit was estimated as 1 mg l−1 dipyrone. The method was applied to pharmaceutical preparations and the results were in agreement with those obtained by the reference procedure with relative deviations within −1.7 and +2.2%.

The paper describes fluidic networks consisting of individually controlled branches. The networks’ basic building blocks are conduits equipped with two electrodes positioned on opposing walls. The entire device is either subjected to an external uniform magnetic field or fabricated within a magnetic material. When a prescribed potential difference is applied across each electrode pair, it induces current in the liquid

In this paper, several designs of an Electrohydrodynamic (EHD) Ion-Drag Micropump will be investigated. The goal is to determine the effect of several design parameters on the pressure-voltage relationship. The overall dimensions of the micropump channel are 500 µm x 480µm x 60µm. Four designs were tested in simulation with different combinations of the gap between the electrodes (S) and the gap between the electrode pairs (D) to examine their impact on the pumping performance. The design with small gap (S) and large gap (D) was found to have the best pumping performance.

This paper studies the thermal behavior of a wireless powered micropump operated using thermo-pneumatic actuation. Numerical analysis was performed to investigate the temporal conduction of the planar inductor-capacitor (LC) wireless heater and the heating chamber. The result shows that the temperature at the heating chamber reaches steady state temperature of 46.7°C within 40 seconds. The finding was further verified with experimental works through the fabrication of the planar LC heater (RF sensitive actuator) and micropump device using MEMS fabrication technique. The fabricated device delivers a minimum volume of 0.096 μL at the temperature of 29°C after being thermally activated for 10 s. The volume dispensed from the micropump device can precisely controlled by an increase of the electrical heating power within the cut-off input power of 0.22 W. Beyond the power, the heat transfer to the heating chamber exhibits non-linear behavior. In addition, wireless operation of the fabricated device shows successful release of color dye when the micropump is immersed in DI-water containing dish and excited by tuning the RF power.

This paper reports on significant progress in the development of an implantable active microport system for an automated administration of aqueous drug suspensions. A novel piezoelectric two-stage micropump ensures the controlled release of minute amounts of fluid with flow rates between 0.1 mul/min and 50 mul/min. A modification of the chamber design reduces the detrimental effect of entrapped air bubbles. Due to an increased compression ratio the micropump has now a full capability to pump gas which enables a reliable self-priming. Moreover, the absence of air bubbles in the pump chamber yields a significantly enhanced accuracy of the delivered fluid volumes.

This paper presents a comparison of thin film materials used as movable membrane for thermal actuated micropump. The materials discussed are PMMA, polyimide, silicon nitride (Si3N4) and single crystal silicon. The properties of membrane material are characterized using Finite Element Analysis (FEA) to study its mechanical and physical behavior that are suitable to be used as an actuator for thermal

This paper presents an approach to the construction and measurements of electrodynamic and reluctance actuators. Executive elements were used as drives in a novel concept of a magnetomotive micropump. The paper discusses various aspects concerning the designation of parameters, control system, the explanation of physical phenomena, and the optimization of the basic elements for coil units. The conducted work describes the measurement system and the analysis of the derived values. The actuators were compared and the pros/cons of building the conceptual device were highlighted. The best solution to be used in the upcoming work concerning the construction of a magnetomotive micropump was chosen based on measurements, engineering aspects, layout control, and key parameters such as the piston velocity, energy stored in capacitors, and efficiencies.

Point-of-care (POC) and disposable biomedical applications demand low-power microfluidic systems with pumping components that provide controlled pressure sources. Unfortunately, external pumps have hindered the implementation of such microfluidic systems due to limitations associated with portability and power requirements. Here, we propose and demonstrate a &#39;finger-powered&#39; integrated pumping system as a modular element to provide pressure head for a variety of advanced microfluidic applications, including finger-powered on-chip microdroplet generation. By utilizing a human finger for the actuation force, electrical power sources that are typically needed to generate pressure head were obviated. Passive fluidic diodes were designed and implemented to enable distinct fluids from multiple inlet ports to be pumped using a single actuation source. Both multilayer soft lithography and injection molding processes were investigated for device fabrication and performance. Experimen...

ABSTRACT Microfluidic CD platforms are utilized to perform different biological processes and chemical analyses. In general, a microfluidic CD implements the centrifugal force that is created by the spinning of the platform to pump liquid through the microfluidic network of chambers and channels. Over the last few decades, a wide range of active and passive valving methods were proposed and tested on various microfluidic platforms. Most of the presented valves are too complex to design and involve lengthy fabrication processes. In this paper, easy to fabricate air and liquid check valves for centrifugal microfluidic platforms are presented: a Terminal Check Valve (TCV) and a Bridge Check Valve (BCV). To understand the characteristic of the proposed valves, theoretical and experimental studies are conducted. Moreover, to test the effectiveness of these valves, liquid swapping is demonstrated by integrating TCV and BCV chips with thermo-pneumatic (TP) pumping on a CD. The valves are shown to accurately control flow direction which makes them an excellent choice for a variety of complex microfluidic processes. The experimental and theoretical results also indicate that these valves require low pressure for actuation. Furthermore, the theoretical results confirm the ability to adjust the required actuation pressure by changing the valve chip size. Finally, as a proof of concept for implementing the check valves on a biological application, an enzyme linked immunosorbent assays (ELISA) is performed. The result shows that the TCV and BCV valving chips enhance the operating range of the processes that can be performed on the microfluidic CD.