Pumping Capability Research Articles

Month-long Respiratory Support by a Wearable Pumping Artificial Lung in an Ovine Model.

A wearable artificial lung could improve lung transplantation outcomes by easing implementation of physical rehabilitation during long-term pretransplant respiratory support. The Modular Extracorporeal Lung Assist System (ModELAS) is a compact pumping artificial lung currently under development. This study evaluated the long-term in vivo performance of the ModELAS during venovenous support in awake sheep. Feedback from early trials and computational fluid dynamic analysis guided device design optimization along the way. The ModELAS was connected to healthy sheep via a dual-lumen cannula in the jugular vein. Sheep were housed in a fixed-tether pen while wearing the device in a holster during support. Targeted blood flow rate and support duration were 2-2.5 L/min and 28-30 days, respectively. Anticoagulation was maintained via systemic heparin. Device pumping and gas exchange performance and hematologic indicators of sheep physiology were measured throughout support. Computational fluid dynamic-guided design modifications successfully decreased pump thrombogenicity from initial designs. For the optimized design, 4 of 5 trials advancing past early perioperative and cannula-related complications lasted the full month of support. Blood flow rate and CO2 removal in these trials were 2.1 ± 0.3 L/min and 139 ± 15 mL/min, respectively, and were stable during support. One trial ended after 22 days of support due to intradevice thrombosis. Support was well tolerated by the sheep with no signs of hemolysis or device-related organ impairment. These results demonstrate the ability of the ModELAS to provide safe month-long support without consistent deterioration of pumping or gas exchange capabilities.

Neurovascular Coupling Impairment in Heart Failure with Reduction Ejection Fraction.

The hemodynamic consequences of a persistent reduced ejection fraction and unknown cardiac output on the brain have not been thoroughly studied. We sought to explore the status of the mechanisms of cerebrovascular regulation in patients with heart failure with reduced (HFrEF) and recovered (HFrecEF) ejection fraction. We monitored cerebral blood flow velocity (CBFV) with transcranial Doppler and blood pressure. Cerebral autoregulation, assessed by transfer function from the spontaneous oscillations of blood pressure to CBFV and neurovascular coupling (NVC) with visual stimulation were compared between groups of HFrEF, HFrecEF and healthy controls. NVC was significantly impaired in HFrEF patients with reduced augmentation of CBFV during stimulation (overshoot systolic CBFV 19.11 ± 6.92 vs. 22.61 ± 7.78 vs. 27.92 ± 6.84, p = 0.04), slower upright of CBFV (rate time to overshoot: 1.19 ± 3.0 vs. 3.06 (4.30) vs. 2.90 ± 3.84, p = 0.02); p = 0.023) and reduced arterial oscillatory properties (natural frequency 0.17 ± 0.06 vs. 0.20 ± 0.09 vs. 0.24 ± 0.07, p = 0.03; attenuation 0.34 ± 0.24 vs. 0.48 ± 0.35 vs. 0.50 ± 0.23, p = 0.05). Cerebral autoregulation was preserved. The neurovascular unit of subjects with chronically reduced heart pumping capability is severely dysfunctional. Dynamic testing with transcranial Doppler could be useful in these patients, but whether it helps in predicting cognitive impairment must be addressed in future prospective studies.

MDO strategy for meridian plane design to improve energy conversion capability of LFR main coolant pump

The design of the LFR main coolant pump (MCP) is a balanced solution between multiple disciplines. Based on the multidisciplinary design optimization (MDO) software ISIGHT, the pump design software CFturbo, PumpLinx and MATLAB are systematically integrated. The geometric structure of the pump is parameterized, in which 6 meridian plane parameters are selected as input parameters, efficiency, head and shaft power are selected as output parameters. Based on the optimal Latin hypercube design, the six input parameters are spatially arranged, and then the RSM models between the input and output are established respectively according to the calculation results. Finally, the six input parameters and the three response indexes are optimized based on the multi-objective optimization algorithm. The method effectively balances the complex design requirements of the MCP, and finally obtains the influence relationship between the coupling effects of different geometric parameters of the meridian plane on the hydraulic performance.

Self-powered microfluidic pump using evaporation from diatom biosilica thin films

In recent years, researchers have successfully applied diatom biosilica to molecular detection platforms including Surface-Enhanced Raman Scattering (SERS) optofluidic sensors that are currently capable of detecting a variety of biological and chemical molecules at concentrations as low as 10−10 M. This study investigates the feasibility of an SERS device that couples the sensing and pumping capabilities of diatom biosilica thin films by determining flow rate limitations and stability. In this paper, we quantify the ability of porous diatom biosilica thin films to continuously pump deionized (DI) water from a reservoir via wicking flow by utilizing the strong capillary forces of the porous film coupled with evaporation. Our microfluidic device is comprised of a narrow horizontal reservoir fixed to a horizontal capillary whose end contacts a diatom biosilica film. Flow rates were controlled by altering the size and/or temperature of the biosilica porous film, determined by tracking the liquid meniscus displacement in the reservoir, and correlated with a modified laminar boundary-layer model. System stability was observed by tracking flow rates over the course of a given experiment, image analysis of the meniscus contacting the film, and a flow duration study. We found that for untreated DI water bubbles begin to form in the capillary tube at temperatures above 40 °C, but degassed water remains stable at temperatures of 90 °C and below. The pumping capabilities of the films ranged from 0.11 to 10.46 µL/min, matched theoretical predictions, demonstrated stable flow trends, and maintained flow for over 48 h.

Effect of Diversion Cavity Geometry on the Performance of Gas-Liquid Two-Phase Mixed Transport Pump

For the purpose of improving the transport capability of the mixed transport pump, a new self-made three-stage deep-sea multiphase pump was taken as the research object. Based on the Euler-Euler heterogeneous flow model, liquid (water) and gas (air) are used as the mixed media to study the external characteristics and internal flow identities of the mixed pump under different gas volume fraction (GVF) conditions. According to the simulation results, a local optimal design scheme of the diversion cavity in the dynamic and static connection section is proposed. The numerical results before and after the optimization are compared and analyzed to explore the effect of the diversion cavity optimization on the performance, blade load and internal flow identities of the pump. The results show that the head and efficiency are obviously improved when the inner wall of the diversion cavity is reduced by 4 mm along the radial direction. After optimization, under the condition of 10% gas content, the head and efficiency is increased by 3.73% and 2.91% respectively. Meanwhile, the hydraulic losses of the diversion cavity and diffuser are reduced by 9.11% and 4.32% respectively. The gas distribution in the impeller is improved obviously and the phenomenon of a large amount of gas phase accumulation is eliminated in the channel. In addition, the abnormal pressure load on the blade surface is eliminated and the turbulent flow energy intensity is reduced. The average turbulent kinetic energy ( T K ) at i = 0.51 of the first stage impeller passage is reduced by 35%. Finally, the reliability of the numerical method is verified by the experimental results. To sum up, the performance and internal flow identities of the optimized mixed transport pump are improved, which verifies the availability and applicability of the optimization results. This provides a reference for the research and design of a multiphase mixed transport pump in the future.

Development of a closed-loop irrigation system for sugarcane farms using the Internet of Things

Better irrigation practices, through increased water use efficiency, can deliver economic, environmental and social benefits to agro-ecological systems. Increasingly, farmers world-wide are turning to automated irrigation systems to save them a significant amount of time by remotely turning on and off pumps and valves. Unfortunately, automated irrigation systems on their own do not provide insight on (i) the amount and timing of irrigation required by the crop or, (ii) how irrigation schedules should change with soil type, farm management and climate. To unravel these complex interactions, an irrigation decision support tool is needed. However, due to the high frequency of irrigations across dozens of irrigation blocks, and the need to irrigate almost all year-round, irrigation decision support tools can be very tedious and time-consuming for farmers to use daily. For these reasons, many farmers will not adopt these tools, and in doing so, fail to optimise irrigation use efficiency due to the multi-factorial nature of the farming system. This paper describes a cybernetic closed-loop solution that was piloted on a sugarcane farm in north-eastern Australia. The solution seeks to improve irrigation management by seamlessly integrating the WiSA automated irrigation system with the IrrigWeb irrigation decision support tool. Specifically, an Uplink program and a Downlink program were implemented in the pilot study. The Uplink program saved the farmer a significant amount of time. Instead of the farmer manually entering in records, Uplink uploaded irrigation and rainfall data directly to the irrigation decision support tool. The Downlink program calculated and applied irrigation schedules automatically using IrrigWeb, but also incorporated practical constraints, such as energy, pumping capability, irrigation priorities and farmer irrigation preference. The simulation results demonstrated that the developed closed-loop solution could effectively manage irrigation scheduling by incorporating irrigation decision support tools with practical constraints. Systems that increase water use efficiency can deliver practical, profitable and environmental benefits to irrigated agricultural systems worldwide.

Evaluation of the Pump Capability of the Primary Cooling of TRIGA 2000 Research Reactor

The TRIGA 2000 research reactor has been operating since mid 2000. Currently, there are plans to convert the reactor core from cylindrical fuel element to plate type fuel element. The conversion process is expected to not change too many existing systems, including the primary cooling systems. For this reason, it is necessary to evaluate the pump capability of the primary cooling system. Based on experimental studies, then merging with the existing installation system head, it has been obtained the main and the redundant pump mass flow rate of 45 and 45.5 kg/s, respectively. The pump capability decreased by around 5 % compared to the results of its commissioning. If the two pumps are combined in parallel, the combined mass flow rate can increase to 62 kg/s. The existing primary pumps cannot be used for primary cooling system if the reactor core is converted into a plate type, even though both pump are installed in parallel. These results need to be considered in designing a new core of the Bandung TRIGA 2000 research reactor with primary cooling systems that are slightly modified because they have to add the decay tank.

CARDIAC POWER AS A PREDICTOR OF MORTALITY IN SEPSIS

The inflammatory response in sepsis results in end stage damage to tissues and a shock state with increasing circulatory failure. Myocardial depression is one of the many complications seen during severe sepsis and septic shock. Cardiac power output (CPO) is a measure of cardiac pumping capability

Centrifugal Pumps as Extractors

AbstractThe generation of dispersions with defined droplet size distributions is important for liquid‐liquid extraction. In this respect, the capability of a centrifugal pump to generate dispersions was investigated for different operating points. For the analysis of the mixing process, a centrifugal pump was designed translucent. High‐speed images reveal the mechanism of particle breakup. Optical measurement technology and image processing with neural networks were used to determine droplet size distributions. The influence of flow rate, rotational frequency and holdup are discussed for a paraffin oil‐water system.

P339 Gradient adjusted cardiac power index does not improve prediction of survival post transcatheter aortic valve replacement compared to cardiac power index alone

Abstract Funding Acknowledgements None Background Cardiac Power Index (CPI) is an integrative hemodynamic measure of cardiac pumping capability and is the product of the simultaneously measured mean arterial pressure (MAP) and cardiac output (CO). In patients with aortic stenosis (AS), MAP is not reflective of mean systolic left ventricular (LV) pressure due to the transvalvular gradient. Non-invasive assessment of mean systolic LV pressure is challenging in severe aortic stenosis. CPI assessed using systemic MAP was previously shown to predict survival post transcatheter aortic valve replacement (TAVR). Purpose We evaluated the utility of a gradient adjusted CPI in predicting survival post TAVR compared to CPI alone Methods A retrospective study was performed including patients undergoing TAVR with 1 year follow-up. Baseline demographics, clinical, and echocardiographic data were abstracted from a cohort of 1,011 patients. CPI was calculated, (CO x MAP)/ (451 x BSA) Watts/m2. Gradient adjusted CPI was calculated using an augmented MAP i) adding aortic valve mean gradient(AVMG) to systolic blood pressure (CPI1); ii) adding aortic valve maximal instantaneous gradient to systolic blood pressure (CPI2) and iii) adding AVMG to MAP (CPI3). Patient survival score was calculated using a step up technique to identify the cut off value for CPI and gradient adjusted CPI to identify, where the maximum difference in mortality occurred. Multivariate cox-regression analysis was performed to adjust for baseline covariates. Receiver operator curves(ROC) for CPI and gradient adjusted CPI were calculated to predict survival post TAVR. Results The mortality rate at 1 yr was 16%. Mean age and AVMG of survivors was 81 +/- 9 yrs and 43 +/-14 mmHg vs 80 +/-9 yrs and 42 +/- 13 mmHg in the deceased group. Proportion of female patients was similar in both groups (p = 0.7). Patients in the deceased group at baseline had a higher prevalence of chronic lung disease, atrial fibrillation, heart failure within 2-weeks of procedure, higher STS-PROM score, lower serum albumin level, higher prevalence of moderate to severe tricuspid regurgitation, higher right ventricular systolic pressure and higher prevalence of dialysis. Both CPI and gradient adjusted CPI were independently associated with survival at 1 year. The area under ROC for CP, CP1, CP2 and CP3 were 0.67 (95% confidence interval [CI] 0.62 - 0.72), 0.65 (95% CI 0.60 – 0.70), 0.66 (95% CI 0.61 – 0.71) and 0.63 (95% CI 0.58 – 0.68) respectively. Conclusion Gradient adjusted CPI did not improve accuracy of predicting post TAVR survival at 1 year compared to CPI alone. Abstract P339 Figure. Area under ROC

Novel self-biasing circuit for dielectric elastomer generator and its parameter optimization

In order to solve the problem that a dielectric elastomer generator (DEG) requires an external high voltage bias supply to improve the autonomy and security of the power generation system so that it could adapt to a changeable environment, and to improve the efficiency of power generation, based on the simulation research and analysis of three traditional self-biasing circuits, a new self-biasing circuit integrated with a self-supplementary circuit has been proposed in this paper. Under the same input conditions, the maximum output potential of the new self-biasing circuit is 2.23 times that of the traditional circuit. The pumping capability of the self-biasing circuit is greatly improved. At the same time, based on this circuit, in order to explore the factors affecting the energy conversion of the DEG, the overall electromechanical parameters of the circuit are compared and optimized by simulation experiments in this paper. The simulation and experimental results show that the capacitance-to-strain ratio of DEG and the mechanical frequency should be as large as possible within the safe range to obtain larger output potential, and the capacitance of charge pump should be 0.75 times of the capacitance of DEG in the initial state to improve efficiency.

Combining linear retention index and electron ionization mass spectrometry for a reliable identification in nano liquid chromatography

The present research is focused on the object to improve identification capability in liquid chromatography (LC), by creating a system as similar as possible to gas chromatography (GC), where the combination/complementarity of Linear Retention Index (LRI) and Electron Ionization Mass Spectrometry (EI-MS) data makes the identification process easy, automatic and reliable. Conversely, in LC the untargeted characterization of real-world samples is still a challenge, due to the not repeatable and poorly informative nature of typical atmospheric pressure ionization mass spectrometry, normally hyphenated to LC. In the last decades the miniaturization of LC instrumentation together with the considerable progresses in MS vacuum pump capability has made the LC-EI-MS hyphenation more feasible. In the present work, a prototypal nanoLC-EI-MS system was used for the determination of typically LC-amenable compunds, such as coumarins, furocoumarins and polymethoxyflavones in citrus essential oils. All the compounds provided high quality EI-MS spectra, evaluated by the comparison with thousands of spectra present in commercial EI-MS libraries. Spectral similarities major than 80% were achieved.Furthermore, an LRI system, based on the use of an alkyl aryl ketone homologue reference series, was proposed as additional filter to achieve a univocal identification. Then, a novel dual-filter LRI/EI-MS library was built and resulted very helpful in the case of isomeric compounds characterized by identical EI-MS spectrum, but different retention behaviour. The very low inter-day variability attained for each LRI value, together with the satisfactory chromatographic resolution of the developed method, led to a 100% reliability of the identification process based on LRI.

Multi-objective optimization of the flush-type intake duct for a waterjet propulsion system

The intake duct is an important component of waterjet propulsion system and its hydraulic performance is directly connected with the capability of the waterjet pump and even the propulsion performance of the system. In order to optimize the flush-type intake duct, the present paper proposes a multi-objective optimization system including Design of Experiments (DOE), Computational Fluid Dynamics (CFD), three-dimensional parametric design, approximate model, the modified Non-dominated Sorting Genetic Algorithm-II (NSGA-II) and a Technique for Ordering Preferences by Similarity to Ideal Solution (TOPSIS). The nonuniformity and perpendicularity of outflow, and hydraulic efficiency for the intake duct are treated as the optimization objectives with four geometrical parameters as the design variables. Local sensitivity analyses indicate that the optimization objectives are significantly affected by the inclination angle and slightly affected by the lip vertical distance of the intake duct. During IVR = 0.3–0.8, the outflow quality and hydraulic efficiency of the optimized intake duct are greatly improved. The nonuniformity after optimization decreases by 27.8% and perpendicularity increases by 3.07% at the design condition of IVR = 0.7 and V s = 19.49 m/s. Based on the flow at the outlet plane of intake duct, the pressure distribution after optimization is very uniform and the tangential velocity is small without obvious secondary flow. During the application to a mixed-flow waterjet propulsion system at various navigation speeds, the nonuniformity of the optimized intake duct decreases by 20.4% and perpendicularity increases by 4.11% on average, demonstrating that the optimized intake duct performs a better outflow quality. It is also noted that the non-uniform flow from the intake duct mainly affects pressure distribution on the suction surface of impeller blade and causes different shaft power. • A multi-objective optimization system is proposed by incorporating DOE, CFD, three-dimensional parametric design, approximate model, the modified NSGA-II and TOPSIS. • The three optimization objectives are significantly affected by the inclination angle and slightly affected by the lip vertical distance. • Non-uniform suction flows mainly affect the flow field on the impeller suction surfaces and cause the difference in the shaft power.

CAD based design of a high energy absorption metal oxide varistor

Metal Oxide Varistors are a very common power electronic device, applied for efficient overvoltage protection at any voltage level. This piece of equipment has a high non-linear current response function of the applied voltage, and, it provides a relatively high heat absorption capacity in case of accidental overvoltage shocks. The crossing response current is clearly activated by temperature of that device, and, by consequent, overheating could be disastrous. Actual researches must be carried out both for a new more performant material as well as for new technical solutions for the design of all equipment integrating them, by studying heat extraction and heat transfer inside a new complex varistor device. Our article proposes a totally new device, used basically for low voltage applications, having a supplementary metal mass added to the body of that varistor, shaped as small disk. It actions like a heat pump immediately after the voltage shock and as additional radiators at the end of the heating process caused by a transitory overvoltage. A CAD solution combined with a finite element model, followed by some experimental results are also presented, for confirming the performance of that newly design. By placing additional metal alloy masses inside a new varistor structure it will have a higher heat pumping and dissipation capability, in order to reduce temperature stress and all aging effects.

A Review of Design Considerations of Centrifugal Pump Capability for Handling Inlet Gas-Liquid Two-Phase Flows

Most of the pumps working under two phase flows conditions are used in petroleum industry applications, like electrical submersible pumps (ESP) for hydrocarbon fluids, in chemistry, nuclear industries and in agriculture for irrigation purposes as well. Two-phase flows always deteriorate overall pump performances compared with single flow conditions. Several papers have been published aiming to understand flow physics and to model all the main mechanisms that govern gas pocket formation and surging phenomena. These mechanisms depend on the pump type, the impeller geometry, the rotational speed, design and off-design liquid flow rate conditions, the volumetric gas fraction, the fluid properties and the inlet pressure. In the present paper, a review on two phase performances from various centrifugal pumps designs is presented, mainly based on experimental results. The main focus is devoted to detect the significant geometrical parameters that: (1) Modify the pump head degradation level under bubbly flow regime assumption; (2) Allow single stage centrifugal pumps keep working under two-phase flow conditions with high inlet void fraction values before pump shut down, whatever the pump performance degradations and liquid production rates should be. Because most of the published experimental studies are performed on dedicated laboratory centrifugal pump models, most of the present review is based on air-water mixtures as the working fluid with inlet pressures close to atmospheric conditions. The following review supposes that gas phase is considered as a non-condensable perfect gas, while the liquid phase is incompressible. Both phases are isolated from external conditions: neither mass nor heat transfer take place between the phases.

Association between heart rate variability and haemodynamic response to exercise in chronic heart failure

Objectives. Heart rate variability (HRV) and haemodynamic response to exercise (i.e. peak cardiac power output) are strong predictors of mortality in heart failure. The present study assessed the relationship between measures of HRV and peak cardiac power output. Design. In a prospective observational study of 33 patients (age 54 ± 16 years) with chronic heart failure with reduced left ventricular ejection fraction (29 ± 11%), measures of the HRV (i.e. R-R interval and standard deviation of normal R-R intervals, SDNN) were recorded in a supine position. All patients underwent maximal graded cardiopulmonary exercise testing with non-invasive (inert gas rebreathing) cardiac output assessment. Cardiac power output, expressed in watts, was calculated as the product of cardiac output and mean arterial blood pressure. Results. The mean RR and SDNN were 837 ± 166 and 96 ± 29 ms, peak exercise cardiac power output 2.28 ± 0.85 watts, cardiac output 10.34 ± 3.14 L/min, mean arterial blood pressure 98 ± 14 mmHg, stroke volume 91.43 ± 40.77 mL/beat, and oxygen consumption 19.0 ± 5.6 mL/kg/min. There was a significant but only moderate relationship between the RR interval and peak exercise cardiac power output (r = 0.43, p = .013), cardiac output (r = 0.35, p = .047), and mean arterial blood pressure (r = 0.45, p = .009). The SDNN correlated with peak cardiac power output (r = 0.42, p = .016), mean arterial blood arterial (r = 0.41, p = .019), and stroke volume (r = 0.35, p = .043). Conclusions. Moderate strength of the relationship between measures of HRV and cardiac response to exercise suggests that cardiac autonomic function is not good indicator of overall function and pumping capability of the heart in chronic heart failure.

Fully-Integrated Charge Pump Design Optimization for Above-Breakdown Biasing of Single-Photon Avalanche Diodes in 0.13-<inline-formula> <tex-math notation="LaTeX">$\mu$ </tex-math> </inline-formula>m CMOS

A design methodology for an area-optimized integrated charge pump is described suitable for on-chip high-voltage reverse bias of single-photon avalanche diodes (SPADs). The high-voltage generation block is implemented in a general-purpose 0.13- $\mu \text{m}$ CMOS process and is capable of generating a maximum regulated output voltage of 17.7 V from an input of 1.8 V. An ON–OFF regulation scheme with dynamic charging and discharging capability of the charge pump provides fast recovery of the output bias voltage during SPAD transients, where overshoot and undershoot must both be corrected during active quench and reset. Following a SPAD avalanche current pulse, the measured transient recovery time is 500 ns from a 150-mV overshoot and a 500-mV undershoot to reach 99% of steady-state output. The implemented SPAD bias generation system occupies 0.175-mm2 chip area, without requiring an off-chip load capacitor.

Real time wall conditioning with lithium powder injection in long pulse H-mode plasmas in EAST with tungsten divertor

Abstract Real-time lithium powder injection has been applied to long-pulse (>30 s) H-mode plasmas in EAST. This replenishes the active lithium surface that is routinely consumed by plasma-wall interactions. The real-time injection of Li powder into long H-mode discharges effectively suppresses impurity influx and controls recycling on EAST, with an ITER-like tungsten upper divertor. With lithium powder injection, the concentrations W, Mo, and C were reduced by 50% compared to ELMy H-mode discharges. During lithium injection, two effects play a role in the suppression of impurities influx: a reduced divertor temperature and heat flux and hence reduced erosion, and impurity trapping via deposition of a Li film onto plasma-facing surfaces. The ‘fresh’ injected lithium replenishes the film deposited during daily morning evaporation, restoring the wall's pumping capability. Thus, a measurable reduction in the global recycling coefficient was observed.

Extended Regression Models for Predicting the Pumping Capability and Viscous Dissipation of Two-Dimensional Flows in Single-Screw Extrusion.

Generally, numerical methods are required to model the non-Newtonian flow of polymer melts in single-screw extruders. Existing approximation equations for modeling the throughput–pressure relationship and viscous dissipation are limited in their scope of application, particularly when it comes to special screw designs. Maximum dimensionless throughputs of , implying minimum dimensionless pressure gradients for low power-law exponents are captured. We present analytical approximation models for predicting the pumping capability and viscous dissipation of metering channels for an extended range of influencing parameters (, and ) required to model wave- and energy-transfer screws. We first rewrote the governing equations in dimensionless form, identifying three independent influencing parameters: (i) the dimensionless down-channel pressure gradient , (ii) the power-law exponent , and (iii) the screw-pitch ratio . We then carried out a parametric design study covering an extended range of the dimensionless influencing parameters. Based on this data set, we developed regression models for predicting the dimensionless throughput-pressure relationship and the viscous dissipation. Finally, the accuracy of all three models was proven using an independent data set for evaluation. We demonstrate that our approach provides excellent approximation. Our models allow fast, stable, and accurate prediction of both throughput-pressure behavior and viscous dissipation.

Simultaneous Pumping and Mixing of Biological Fluids in a Double-Array Electrothermal Microfluidic Device

Transport and mixing of minute amounts of biological fluids are significantly important in lab-on-a-chip devices. It has been shown that the electrothermal technique is a suitable candidate for applications involving high-conductivity biofluids, such as blood, saliva, and urine. Here, we introduce a double-array AC electrothermal (ACET) device consisting of two opposing microelectrode arrays, which can be used for simultaneous mixing and pumping. First, in a 2D simulation, an optimum electrode-pair configuration capable of achieving fast transverse mixing at a microfluidic channel cross-section is identified by comparing different electrode geometries. The results show that by adjusting the applied voltage pattern and position of the asymmetrical microelectrodes in the two arrays, due to the resultant circular flow streamlines, the time it takes for the analytes to be convected across the channel cross-section is reduced by 95% compared to a diffusion-only-based transport regime, and by 80% compared to a conventional two-layer ACET device. Using a 3D simulation, the fluid transport (pumping and mixing) capabilities of such an electrode pair placed at different angles longitudinally relative to the channel was studied. It was found that an asymmetrical electrode configuration placed at an angle in the range of can significantly increase transversal mixing efficiency while generating strong longitudinal net flow. These findings are of interest for lab-on-a-chip applications, especially for biosensors and immunoassays, where mixing analyte solutions while simultaneously moving them through a microchannel can greatly enhance the sensing efficiency.