Temporal Response of Porous Glass Electroosmotic Pumps

2002 ◽  
Author(s):  
Shuhuai Yao ◽  
Shulin Zeng ◽  
Juan G. Santiago
Keyword(s):  
Flow Rate ◽  
Maximum Flow ◽  
Ion Concentration ◽  
Temporal Response ◽  
Short Term ◽  
Cooling Systems ◽  
Sintered Glass ◽  
Rate Capacity ◽  
Bioanalytical Applications ◽  
Electroosmotic Pumps

Sintered glass electroosmotic pumps have been fabricated that provide maximum flow rates and pressure capacities exceeding 14 ml/min and 1.4 atm, respectively, at 150 V, with an active pumping volume of less than 2 cm3. These compact devices with no moving parts have the potential to impact a variety of applications including microelectronics cooling systems and bioanalytical applications. We present here a preliminary a study of the response of the pumps to changes in fluidic load, including their short-term transient performance. A 0.5 mM borate buffer (pH = 9.2) is used to stabilize pump performance, with nearly optimal flow rate capacity. The experiments are conducted for working electrolytes of varying ion concentration. These performance characteristics are critical to applications that aim to use feedback control of flow rate and pressure over varying conditions.

Thermodynamic Efficiency of Porous Glass Electroosmotic Pumps

2003 ◽  
Author(s):  
Shuhuai Yao ◽  
Shulin Zeng ◽  
Juan G. Santiago
Keyword(s):  
Zeta Potential ◽  
Flow Rate ◽  
Maximum Flow ◽  
Pump Current ◽  
Thermodynamic Efficiency ◽  
Two Phase ◽  
Poisson Boltzmann ◽  
Electroosmotic Pumps ◽  
Poisson Boltzmann Equation ◽  
Pump Pressure

This paper presents an analytical and experimental study of electroosmotic (EO) pumps designed to be integrated with two-phase microchannel heat exchangers with load capacities of order 100 W and greater. We have fabricated sintered glass EO pumps that provide maximum flow rates and pressure capacities 33 ml/min and 1.3 atm, respectively, at 100 V applied potentials. We have developed an analytical model to solve for electroosmotic flow rate, total pump current, and thermodynamic efficiency as a function of pump pressure load for these porous-structure EO pumps. The model uses a symmetric electrolyte approximation valid for the high zeta potential regime and numerically solves the Poisson-Boltzmann equation for charge distribution in the idealized pore geometry. The model also incorporates an approximate ionic-strength-dependent zeta potential formulation. The effects of pressure and flow rate on thermodynamic efficiency are also analyzed theoretically and compared to our measurements.

Compact Modeling of Fractal Tree-Shaped Microchannel Liquid Cooling Systems

2011 ◽  
Author(s):  
Cheng Chen ◽  
Emad Samadiani ◽  
Bahgat Sammakia
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Maximum Flow ◽  
Heat Fluxes ◽  
Compact Model ◽  
Temperature Fields ◽  
Compact Modeling ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Full Field

Demands for higher computational speed and miniaturization have already resulted in extremely high heat fluxes in microprocessors. Fractal tree-shaped microchannel liquid cooling systems are novel heat transfer enhancement systems to keep the temperature of the microprocessors in a safe range. Due to the complexity of these systems, their full field numerical modeling for simulation of the flow and temperature fields is too time consuming and costly, particularly to be used within iterative optimization algorithms. In this paper, a quick but still accurate compact modeling approach based on Flow Network Modeling (FNM) is introduced for analysis of the flow filed in fractal microchannel liquid cooling systems. The compact method is applied to a representative fractal microchannel cooling system and the obtained velocity and flow rate distribution are validated against a full Computational Fluid Dynamics (CFD)-based model for three different designs. The compact model shows good agreement with the CFD results and robustness on different designs, while requiring much less computational capability and time. Afterwards, the compact model is used for optimization of the geometry of the fractal cooling system to achieve maximum flow rate and uniform flow distribution among the channels for a fixed pressure drop.

scholarly journals A large opening and high flow rate  piezoelectric pump with straight arm wheeled check valve

2020 ◽  
Author(s):  
Lipeng He ◽  
Xiaoqiang Wu ◽  
Zhe Wang ◽  
Da Zhao ◽  
Jianming Wen ◽  
...  
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Check Valve ◽  
Maximum Flow ◽  
Low Flow ◽  
Piezoelectric Pump ◽  
Cooling Systems ◽  
Microelectronic Devices ◽  
Valve Opening ◽  
Large Opening

Abstract Piezoelectric pumps are applied in cooling systems of microelectronic devices because of their small size. However, cooling efficiency is limited by low flow rate. A Straight arm wheeled check valve made of silica gel was proposed, which can improve flow rate of piezoelectric pump, solve the influence of glue aging on the sealing ability of a wheeled check valve and reduce the size of piezoelectric pump. This paper discusses the influence of valve arm number (N=2, 3 and 4), valve arm width (W=1.0, 1.2 and 1.4mm) and valve thickness (T=0.6, 0.8 and 1.0mm) on flow rate characteristics of piezoelectric pumps. When valve opening rises, the flow rate increases. The simulation results show that valves with 2 valve arms, 0.6mm valve thickness and 1.0mm valve arm width have maximum valve opening. Experimental results show that piezoelectric pumps with different valve parameters have different optimal frequencies. In addition, maximum flow rate is 431.6mL/min at 220V and 70Hz. This paper provides a reference for the application of piezoelectric pump in cooling system.

Electroosmotic Pumps Fabricated From Porous Silicon Membranes

2004 ◽  
Author(s):  
Shuhuai Yao ◽  
Alan M. Myers ◽  
Jonathan D. Posner ◽  
Juan G. Santiago
Keyword(s):  
Porous Silicon ◽  
Flow Rate ◽  
Maximum Flow ◽  
Applied Potential ◽  
Flow Rates ◽  
Pump Performance ◽  
Silicon Membranes ◽  
Electroosmotic Pumps ◽  
The Impact ◽  
Large Flow

Large flow rates per applied potential are obtained from electroosmotic (EO) pumps fabricated from n-type porous silicon. Porous silicon membranes have ideal geometries for EO pumping. These membranes have hexagonally packed, uniform pores with near-unity tortuosity and are well suited to maximize flow rate for a given applied voltage. The 350 μm thick membranes were passivated with a SiO2 layer and exhibit a maximum flow rate of 1.2 ml/min/cm2/V. This is 4.4 times higher than previously demonstrated silica-based frit EO pumps. LPCVD polysilicon deposition followed by wet oxidation was used to control the pore size. The impact of these coatings on the pump performance has also been characterized.

The use of bipolar PlasmaKinetic resectoscope in endoscopic resection of the prostate: our experience

2007 ◽  
Vol 74 (3) ◽  
pp. 160-163
Author(s):  
G. Passavanti ◽  
V. Pizzuti ◽  
A. Bragaglia ◽  
F. Mengoni ◽  
F.M. Costantini ◽  
...  
Keyword(s):  
Endoscopic Resection ◽  
Flow Rate ◽  
New Technologies ◽  
Reference Method ◽  
Hemoglobin Concentration ◽  
Maximum Flow ◽  
Maximum Flow Rate ◽  
Short Term ◽  
Continuous Irrigation ◽  
The Past

Prostatic endoscopic resection (TURP) is a reference method in the treatment of prostatic obstruction. In the past decades, the method used a monopolar resectoscope. In the last years, various technologies have been studied to improve the efficacy of endoscopic resection. As per our experience, we have thence ascertained the variations of the hematic crasis and of the mictional asset in TURP patients treated with bipolar knives. 20 patients underwent bipolar plasmakinetic resection of the prostate. Their age ranged between 58 yrs and 82 yrs (av: 70.2 yrs), the adenoma volume, checked with TR ultrasound scanning, was between 33 and 44 cc (av: 37.6), the Qmax was between 6.4 and 9.0 mL/min (av.: 7.42 mL/min). A 24Ch resectoscope and spinal anesthesia were used. Bleeding during resection was never relevant; therefore resection never had to be stopped. After about 36 hours from surgery, the patients’ sanguification was checked again: a 6.53% reduction of the number of erythrocytes, compared to pre-surgery data, was observed, together with a 6.73% decrease of hemoglobin concentration, and a 6.3% decrease of hematocrit. Continuous irrigation was suspended during the first day, catheter was removed on the 48th hour in 15 cases, and on the 72nd in 5 cases: the patients were discharged on day 3 in 16 cases, and on day 4 in 4 cases. A flux evaluation was performed after 3 months, which showed a Qmax between 16.6 and 24 mL/min (av.: 19.11), with a significant increase in the maximum flow rate. The use of the new technologies in prostatic endoscopic resection has allowed us to improve the efficacy of such a method. Above all, the use of a bipolar electrosurgical knife enables us to associate a basal hemostasis with the resection of the prostatic tissue. Thus, the hematic loss is low, as we have been able to ascertain also in our own experience. This gave us the possibility to quickly stop continuous irrigation and to early remove the catheter. This way, hospitalization was sensibly reduced (av. 76.8 hours). The maximum flow rate, in the short term, has been good. We have been able, in our experience, to assess that this technology represents a useful guarantee to improve the results of prostatic endoscopic resection.

Outcome of Buccal Mucosal Graft Urethroplasty in Long Segment Anterior Urethral Stricture

2020 ◽  
Vol 19 (2) ◽  
pp. 64-68
Author(s):  
Mrinmoy Biswas ◽  
Sudip Das Gupta ◽  
Mohammed Mizanur Rahman ◽  
Sharif Mohammad Wasimuddin
Keyword(s):  
Urethral Stricture ◽  
Flow Rate ◽  
Surgical Outcome ◽  
Simple Technique ◽  
Anterior Segment ◽  
Maximum Flow ◽  
Anastomotic Site ◽  
Buccal Mucosal Graft ◽  
Male Patients

Objective: To assess the success of BMG urethroplasty in long segment anterior urethral stricture. Method: From January 2014 to December 2015, twenty male patients with long anterior segment urethral stricture were managed by BMG urethroplasty. After voiding trial they were followed up at 3 month with Uroflowmetry, RGU & MCU and PVR measurement by USG. Patients were further followed up with Uroflowmetry and PVR at 6 months interval.Successful outcome was defined as normal voiding with a maximum flow rate >15ml /sec and PVR<50 ml with consideration of maximum one attempt of OIU after catheter removal. Results: Mean stricture length was 5.2 cm (range 3-9 cm) and mean follow-up was 15.55 months (range 6-23 months). Only two patients developed stricture at proximal anastomotic site during follow-up. One of them voided normally after single attempt of OIU. Other one required second attempt of OIU and was considered as failure (5%). Conclusion: BMG urethroplasty is a simple technique with good surgical outcome. Bangladesh Journal of Urology, Vol. 19, No. 2, July 2016 p.64-68

Research on an axial-mounted dual magnetostrictive material rods-based electro-hydrostatic actuator

2021 ◽  
pp. 1045389X2110145
Author(s):  
Yuchuan Zhu ◽  
Chang Liu ◽  
Yunze Song ◽  
Long Chen ◽  
Yulei Jiang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Flow Rate ◽  
Flow Distribution ◽  
Maximum Flow ◽  
Magnetostrictive Material ◽  
Simulation Techniques ◽  
Motion State ◽  
New Type ◽  
Output Characteristics ◽  
Active Rectification

In this paper, an electro-hydrostatic actuator driven by dual axial-mounted magnetostrictive material rods-based pumps (MMPs) with a new type of active rectification valve is designed in the current study. Based on flow distribution of the active rectification valve and driving energy provided by two MMPs, the actuator can output continuous and bidirectional displacement. By establishing a mathematical model of the actuating system, using simulation techniques, the change rule of hydraulic cylinder’s motion state caused by different driving signals are studied and analyzed. Test equipment platform is constructed in the laboratory to test the output characteristics and confirm the feasibility of the new concept. The experimental results indicate that the maximum flow rate can reach approximately 2.7 L·min−1, while the operating frequency is 180 Hz.

Lichen sclerosis–induced long segment anterior urethral stricture: The early outcome of one-stage repair using dorsolateral onlay buccal mucosa graft

2021 ◽  
pp. 039156032110033
Author(s):  
Atef Fathi ◽  
Omar Mohamed ◽  
Osama Mahmoud ◽  
Gamal A Alsagheer ◽  
Ahmed M Reyad ◽  
...  
Keyword(s):  
Success Rate ◽  
Urethral Stricture ◽  
Flow Rate ◽  
Urine Volume ◽  
Maximum Flow ◽  
Maximum Flow Rate ◽  
P Value ◽  
Onlay Graft ◽  
Voiding Symptoms ◽  
Stricture Recurrence

Background: Substitution urethroplasty using buccal mucosal grafts can be performed by several approaches including ventral onlay graft, dorsal onlay graft, or ventral urethrotomy with dorsal inlay graft. Our study aims to evaluate the surgical outcome of dorsolateral buccal mucosal graft for long segment anterior urethral stricture >6 cm in patients with Lichen sclerosus (LS). Methods: A retrospective study included patients who underwent repair for long segment anterior urethral stricture >6 cm due to LS between January 2013 and April 2019. All patients were followed-up at 3, 6, 9, and 12 months postoperatively and then yearly by clinical symptoms, uroflowmetry, and calculation of post-void residual urine volume. Retrograde urethrogram was requested for patients with voiding symptoms or decreased maximum flow rate. Stricture recurrence that required subsequent urethrotomy or urethroplasty was considered failure. The success rate and surgical complications were collected and analyzed. Results: Thirty patients were identified. The median age (range) was 39 (25–61) years and a median (range) stricture length was 8 (6–14) cm. Most of postoperative complications were of minor degree. The success rate at median follow-up of 15 (12–24) months was 86.5%. The median maximum flow rate increased significantly from 6 (2–11) ml/s preoperatively to 18 (range: 6–23) ml/s at the 6th month ( p value < 0.001). Conclusion: Dorsolateral buccal mucosal grafts urethroplasty for long anterior urethral stricture caused by LS has a high success rate and low risk of complications including stricture recurrence.

scholarly journals Improving Output Performance of a Resonant Piezoelectric Pump by Adding Proof Masses to a U-Shaped Piezoelectric Resonator

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 500
Author(s):  
Jian Chen ◽  
Wenzhi Gao ◽  
Changhai Liu ◽  
Liangguo He ◽  
Yishan Zeng
Keyword(s):  
Flow Rate ◽  
Maximum Flow ◽  
Working Fluid ◽  
Driving Voltage ◽  
Piezoelectric Resonator ◽  
Piezoelectric Pump ◽  
Compact Structure ◽  
Output Performance ◽  
Volume Efficiency ◽  
Working Efficiency

This study proposes the improvement of the output performance of a resonant piezoelectric pump by adding proof masses to the free ends of the prongs of a U-shaped piezoelectric resonator. Simulation analyses show that the out-of-phase resonant frequency of the developed resonator can be tuned more efficiently within a more compact structure to the optimal operating frequency of the check valves by adjusting the thickness of the proof masses, which ensures that both the resonator and the check valves can operate at the best condition in a piezoelectric pump. A separable prototype piezoelectric pump composed of the proposed resonator and two diaphragm pumps was designed and fabricated with outline dimensions of 30 mm × 37 mm × 54 mm. Experimental results demonstrate remarkable improvements in the output performance and working efficiency of the piezoelectric pump. With the working fluid of liquid water and under a sinusoidal driving voltage of 298.5 Vpp, the miniature pump can achieve the maximum flow rate of 2258.9 mL/min with the highest volume efficiency of 77.1% and power consumption of 2.12 W under zero backpressure at 311/312 Hz, and the highest backpressure of 157.3 kPa under zero flow rate at 383 Hz.

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