Optical micro/nanofibre embedded soft film enables multifunctional flow sensing in microfluidic chips

Lab on a Chip ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 2572-2579
Author(s):  
Zhang Zhang ◽  
Jing Pan ◽  
Yao Tang ◽  
Yue Xu ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Microfluidic Chip ◽  
Microfluidic Chips ◽  
Flow Sensing

A smart microfluidic chip enabled by optical micro/nanofibres embedded soft film can detect flow rate, count droplets, and predict the morphology of droplets.

Preparation of Monodisperse PEG Microspheres by a T-Junction Microfluidic Chip

2012 ◽  
Vol 465 ◽  
pp. 178-181 ◽  
Author(s):  
Yu Min Ren ◽  
Bing Yu ◽  
Hai Lin Cong ◽  
Yu Rong Ma ◽  
Zhen Zhen Ma ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Flow Rate ◽  
Microfluidic Chip ◽  
Uv Exposure ◽  
Microfluidic Channels ◽  
Microfluidic Chips ◽  
Silicon Oil ◽  
Sample Flow Rate ◽  
Rate Ratios

Monodisperse polyethylene glycol (PEG) microspheres were prepared using microfluidic chips coupled with photopolymerization technique. Based on sheath effect in T-junction microfluidic channels, dispersions of uniform PEG prepolymer droplets in silicon oil are formed. The diameters of the formed PEG prepolymer droplets in the dispersions were controlled very well by altering the relative sheath/sample flow rate ratios. After photopolymerization under UV exposure, the uniform PEG prepolymer droplets isolated by silicon oil underwent photocrosslinking and became monodisperse PEG microspheres.

scholarly journals Programmable hydraulic resistor for microfluidic chips using electrogate arrays

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Marie L. Salva ◽  
Yuksel Temiz ◽  
Marco Rocca ◽  
Yulieth C. Arango ◽  
Christof M. Niemeyer ◽  
...  
Keyword(s):  
Flow Rate ◽  
Microfluidic Chip ◽  
Rate Control ◽  
Flow Resistance ◽  
Smartphone Application ◽  
Microfluidic Chips ◽  
Specific Flow ◽  
Flow Rates ◽  
Peripheral Device ◽  
Flow Rate Control

AbstractFlow rates play an important role in microfluidic devices because they affect the transport of chemicals and determine where and when (bio)chemical reactions occur in these devices. Flow rates can conveniently be determined using external peripherals in active microfluidics. However, setting specific flow rates in passive microfluidics is a significant challenge because they are encoded on a design and fabrication level, leaving little freedom to users for adjusting flow rates for specific applications. Here, we present a programmable hydraulic resistor where an array of “electrogates” routes an incoming liquid through a set of resistors to modulate flow rates in microfluidic chips post-fabrication. This approach combines a battery-powered peripheral device with passive capillary-driven microfluidic chips for advanced flow rate control and measurement. We specifically show a programmable hydraulic resistor composed of 7 parallel resistors and 14 electrogates. A peripheral and smartphone application allow a user to activate selected electrogates and resistors, providing 127 (27-1) flow resistance combinations with values spanning on a 500 fold range. The electrogates feature a capillary pinning site (i.e. trench across the flow path) to stop a solution and an electrode, which can be activated in a few ms using a 3 V bias to resume flow based on electrowetting. The hydraulic resistor and microfluidic chip shown here enable flow rates from ~0.09 nL.s−1 up to ~5.66 nL.s−1 with the resistor occupying a footprint of only 15.8 mm2 on a 1 × 2 cm2 microfluidic chip fabricated in silicon. We illustrate how a programmable hydraulic resistor can be used to set flow rate conditions for laminar co-flow of 2 liquids and the enzymatic conversion of a substrate by stationary enzymes (alkaline phosphatase) downstream of the programmable hydraulic resistor.

Study on the Manufacture of Microfluidic Chip with Coated Glass

2012 ◽  
Vol 548 ◽  
pp. 254-257 ◽  
Author(s):  
Yan He ◽  
Bai Ling Huang ◽  
Yong Lai Zhang ◽  
Li Gang Niu
Keyword(s):  
Microfluidic Chip ◽  
Low Cost ◽  
Microfluidic Channel ◽  
Critical Factor ◽  
Wet Etching ◽  
Microfluidic Chips ◽  
Etching Technique ◽  
Chip Quality ◽  
Wet Chemical ◽  
Wet Chemical Etching

In this paper, a simple and facile technique for manufacturing glass-based microfluidic chips was developed. Instead of using expensive dry etching technology, the standard UV lithography and wet chemical etching technique was used to fabricate microchannels on a K9 glass substrate. The fabrication process of microfluidic chip including vacuum evaporation, annealing, lithography, and BHF (HF-NH4F-H2O) wet etching were investigated. Through series experiments, we found that anneal was the critical factor for chip quality. As a representative example, a microfluidic channel with 20 m of depth, and 80 m of width was successfully prepared, and the channel surfaces are quite smooth. These results present a simple, low cost, flexible and easy way to fabricate glass-based microfluidic chips.

scholarly journals Multistage Digital-to-Analogue Chip Based on a Weighted Flow Resistance Network for Soft Actuators

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1016
Author(s):  
Zhou Zhou ◽  
Manman Xu ◽  
Chenlin Zhu ◽  
Gonghan He ◽  
Kunpeng Zhang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Microfluidic Chip ◽  
Flow Resistance ◽  
Design Method ◽  
Control Unit ◽  
Digital Signal ◽  
Technical Problems ◽  
Pressure Signal ◽  
Resistance Network ◽  
Flow Adjustment

A control chip with a multistage flow-rate regulation function based on the correlation between the flow resistance and flow rate has been developed in this article. Compared with the traditional proportional solenoid valve, this kind of flow valve based on microfluidic technology has the characteristics of being light-weight and having no electric drive. It solves such technical problems as how the current digital microfluidic chip can only adjust the flow switch, and the adjustment of the flow rate is difficult. To linearize the output signal, we propose a design method of weighted resistance. The output flow is controlled by a 4-bit binary pressure signal. According to the binary value of the 4-bit pressure signal at the input, the output can achieve 16-stage flow adjustment. Furthermore, we integrate the three-dimensional flow resistance network, multilayer structure microvalve, and parallel fluid network into a single chip by using 3D printing to obtain a modular flow control unit. This structure enables the microflow control signal to be converted from a digital signal to an analogue signal (DA conversion), and is suitable for microflow driving components, such as in microfluidic chip sampling systems and proportional mixing systems. In the future, we expect this device to even be used in the automatic control system of a miniature pneumatic soft actuator.

scholarly journals Local flow sensing on helical microrobots for semi-automatic motion adaptation

2019 ◽  
Vol 39 (4) ◽  
pp. 476-489 ◽  
Author(s):  
Antoine Barbot ◽  
Dominique Decanini ◽  
Gilgueng Hwang
Keyword(s):  
Closed Loop ◽  
Flow Speed ◽  
Closed Loop Control ◽  
Flow Profile ◽  
Microfluidic Chips ◽  
Level Control ◽  
Local Flow ◽  
Loop Control ◽  
Flow Sensing ◽  
Swimming Motion

Helical microrobots with dimensions below 100 µm could serve many applications for manipulation and sensing in small, closed environments such as blood vessels or inside microfluidic chips. However, environmental conditions such as surface stiction from the channel wall or local flow can quickly result in the loss of control of the microrobot, especially for untrained users. Therefore, to automatically adapt to changing conditions, we propose an algorithm that switches between a surface-based motion of the microrobot and a 3D swimming motion depending on the local flow value. Indeed swimming is better for avoiding obstacles and difficult surface stiction areas but it is more sensitive to the flow than surface motion such as rolling or spintop motion. First, we prove the flow sensing ability of helical microrobots based on the difference between the tracked and theoretical speed. For this, a 50 µm long and 5 µm diameter helical microrobot measures the flow profile shape in two different microchannels. These measurements are then compared with simulation results. Then, we demonstrate both swimming and surface-based motion using closed-loop control. Finally, we test our algorithm by following a 2D path using closed-loop control, and adapting the type of motion depending on the flow speed measured by the microrobot. Such results could enable simple high-level control that could expand the development of microrobots toward applications in complex microfluidic environments.

scholarly journals A novel microfluidic chip-based sperm-sorting device constructed using design of experiment method

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chalinee Phiphattanaphiphop ◽  
Komgrit Leksakul ◽  
Rungrueang Phatthanakun ◽  
Trisadee Khamlor
Keyword(s):  
Microfluidic Device ◽  
Flow Rate ◽  
Microfluidic Chip ◽  
Design Of Experiment ◽  
Fluid Viscosity ◽  
Inlet Flow ◽  
Factors Affecting ◽  
Inlet Flow Rate ◽  
Sperm Sorting ◽  
Bull Sperm

Abstract Microfluidics is proposed as a technique for efficient sperm sorting, to achieve the ultimate goal of resolving infertility problems in livestock industry. Our study aimed to design a microfluidic sperm-sorting device (SSD) through a high-efficacy and cost- and time-effective fabrication process, by using COMSOL Multiphysics simulation and modeling software, and the design of experiment (DOE) method. The eight factors affecting SSD performance were established. The simulation was then run, and statistically significant factors were analyzed. Minitab16 was used to optimize the design modulus factor. By setting the statistical significance at p < 0.05, the factors affecting experimental structure were analyzed. At a desirability of 97.99, the optimal parameters for the microfluidic chip were: angle between sperm and medium inlet chambers (A = 43°), sperm inlet flow rate (B = 0.24 µL min−1), medium inlet flow rate (C = 0.34 µL min−1), and inlet and outlet chamber lengths (D = 5000 µm). These optima were then applied to microfluidics device construction. The device was produced using soft lithographic microfabrication techniques and tested on Holstein–Friesian bull sperm. The highest bull sperm-sorting performance for this microfluidic device prototype was 96%. The error between the simulation and the actual microfluidic device was 2.72%. Fluid viscosity ranges analysis-based simulations revealed acceptable fluid viscosity tolerances for the SSD. The simulation results revealed that the acceptable tolerance range for fluid viscosity was 0.00001–0.003 kg m−1 s−1. This optimally designed microfluidic chip-based SSD may be integrated into sperm x/y separation micro devices.

scholarly journals Direct demonstration of tubular fluid flow sensing by macula densa cells

2010 ◽  
Vol 299 (5) ◽  
pp. F1087-F1093 ◽  
Author(s):  
Arnold Sipos ◽  
Sarah Vargas ◽  
János Peti-Peterdi
Keyword(s):  
Smooth Muscle ◽  
Fluid Flow ◽  
Smooth Muscle Cells ◽  
Flow Rate ◽  
Muscle Cells ◽  
Macula Densa ◽  
Fluid Composition ◽  
Apical Surface ◽  
Fluid Flow Rate ◽  
Flow Sensing

Macula densa (MD) cells in the cortical thick ascending limb (cTAL) detect variations in tubular fluid composition and transmit signals to the afferent arteriole (AA) that control glomerular filtration rate [tubuloglomerular feedback (TGF)]. Increases in tubular salt at the MD that normally parallel elevations in tubular fluid flow rate are well accepted as the trigger of TGF. The present study aimed to test whether MD cells can detect variations in tubular fluid flow rate per se. Calcium imaging of the in vitro microperfused isolated JGA-glomerulus complex dissected from mice was performed using fluo-4 and fluorescence microscopy. Increasing cTAL flow from 2 to 20 nl/min (80 mM [NaCl]) rapidly produced significant elevations in cytosolic Ca2+ concentration ([Ca2+]i) in AA smooth muscle cells [evidenced by changes in fluo-4 intensity (F); F/F0 = 1.45 ± 0.11] and AA vasoconstriction. Complete removal of the cTAL around the MD plaque and application of laminar flow through a perfusion pipette directly to the MD apical surface essentially produced the same results even when low (10 mM) or zero NaCl solutions were used. Acetylated α-tubulin immunohistochemistry identified the presence of primary cilia in mouse MD cells. Under no flow conditions, bending MD cilia directly with a micropipette rapidly caused significant [Ca2+]i elevations in AA smooth muscle cells (fluo-4 F/F0: 1.60 ± 0.12) and vasoconstriction. P2 receptor blockade with suramin significantly reduced the flow-induced TGF, whereas scavenging superoxide with tempol did not. In conclusion, MD cells are equipped with a tubular flow-sensing mechanism that may contribute to MD cell function and TGF.

Design and Fabrication of Micro Hot Embossing Mold for Microfluidic Chip Used in Flow Cytometry

2007 ◽  
Vol 339 ◽  
pp. 246-251
Author(s):  
L.Q. Du ◽  
C. Liu ◽  
H.J. Liu ◽  
J. Qin ◽  
N. Li ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Microfluidic Chip ◽  
Low Cost ◽  
Hot Embossing ◽  
Microfluidic Chips ◽  
Metal Mold ◽  
Nickel Electroforming ◽  
Thick Photoresist ◽  
Nickel Base ◽  
Microfabrication Technology

Micro hot embossing mold of microfluidic chip used in flow cytometry is designed and microfabricated. After some kinds of microfabrication processes are tried, this paper presents a novel microfabrication technology of micro hot embossing metal mold. Micro metal mold is fabricated by low-cost UV-LIGA surface micro fabrication process using negative thick photoresist, SU-8. Different from other micro hot embossing molds, the micro mold with vertical sidewalls is fabricated by micro nickel electroforming directly on Nickel base. Based on the micro Nickel mold and automation fabrication system, high precision and mass-producing microfluidic chips have been fabricated and they have been used in flow cytometry

Surface Microfabrication of Conventional Glass Using Femtosecond Laser for Microfluidic Applications

2017 ◽  
Vol 11 (6) ◽  
pp. 878-882 ◽  
Author(s):  
Takuma Niioka ◽  
◽  
Yasutaka Hanada
Keyword(s):  
High Resolution ◽  
Microfluidic Chip ◽  
High Speed ◽  
Single Cell Analysis ◽  
Glass Slide ◽  
Cell Analysis ◽  
Microfluidic Chips ◽  
Direct Writing ◽  
Laser Direct Writing ◽  
Fs Laser

Recently, a lot of attention has been paid to a single-cell analysis using microfluidic chips, since each cell is known to have several different characteristics. The microfluidic chip manipulates cells and performs high-speed and high-resolution analysis. In the meanwhile, femtosecond (fs) laser has become a versatile tool for the fabrication of microfluidic chips because the laser can modify internal volume solely at the focal area, resulting in three-dimensional (3D) microfabrication of glass materials. However, little research on surface microfabrication of materials using an fs laser has been conducted. Therefore, in this study, we demonstrate the surface microfabrication of a conventional glass slide using fs laser direct-writing for microfluidic applications. The fs laser modification, with successive wet etching using a diluted hydrofluoric (HF) acid solution, followed by annealing, results in rapid prototyping of microfluidics on a conventional glass slide for fluorescent microscopic cell analysis. Fundamental characteristics of the laser-irradiated regions in each experimental procedure were investigated. In addition, we developed a novel technique combining the fs laser direct-writing and the HF etching for high-speed and high-resolution microfabrication of the glass. After establishing the fs laser surface microfabrication technique, a 3D microfluidic chip was made by bonding the fabricated glass microfluidic chip with a polydimethylsiloxane (PDMS) polymer substrate for clear fluorescent microscopic observation in the microfluidics.

A Microfluidic Device for Sample Pretreatment by Laminar Flow Extraction

2014 ◽  
Vol 511-512 ◽  
pp. 8-11
Author(s):  
Da Lei Li ◽  
Xue Fei Lv ◽  
Yu Lin Deng
Keyword(s):  
Aqueous Solution ◽  
Laminar Flow ◽  
Microfluidic Device ◽  
Microfluidic Chip ◽  
Extraction Efficiency ◽  
Sample Pretreatment ◽  
Microfluidic Chips ◽  
Two Phase ◽  
Phase Fluid ◽  
Potential Tool

Microfluidic chip is the most active field and frontier of μTAS. In comparison to other aspects of researches on microfluidic chips, the work on sample pretreatment units are in the preliminary stage. In this study, a microfluidic device for extraction was devised and fabricated. The extraction efficiency of the microfluidic device was investigated by two phase fluid 0.1% Rhodamine-B aqueous solution and Hexyl alcohol. The results demonstrated that the microfluidic chip worked well in the first two days and might be integrated in a complex chip as a potential tool for sample pretreatment.

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