Microchannel Height Research Articles

Performance analysis of a low-pressure cryogenic vaporizer for liquified hydrogen supply system

In this paper, we theoretically investigated the thermal performance of a low-pressure cryogenic vaporizer for liquified hydrogen supply system. A performance analysis model was developed by the modified effectiveness-NTU method considering the axial conduction and phase change of liquified hydrogen. In the analysis model, a plate-fin heat exchanger (PFHE) was chosen as the type of a cryogenic vaporizer. The inlet temperature and pressure conditions of liquified hydrogen were 20 K and 10 bar, respectively and the outlet temperature condition of hydrogen was a room temperature. Based on the theoretical results, we presented effects of geometric parameters on the performance of the vaporizer under the fixed pumping power condition. Especially, it is shown that the effectiveness of the hot fluid and cold fluid exhibit opposite trends depending on the axial conduction. In addition, we presented the effect of the aspect ratio of microchannels on the effectiveness considering both cases where the microchannel heights of the EGW mixture and hydrogen were either the same or different. Also, we showed the effect of the vaporizer length on the performance of the vaporizer. Finally, geometric parameters that can satisfy the two target performances are suggested.

Computational modelling of the therapeutic outputs of photodynamic therapy on spheroid-on-chip models

Photodynamic therapy (PDT) is a medical radio chemotherapeutic method that uses light, photosensitizing agents, and oxygen to produce cytotoxic compounds, which eliminate malignant cells. Recently, Microfluidic systems have been used to analyse photosensitizers (PSs) due to their potential to replicate in vivo environments. While prior studies have established a strong correlation between reacted singlet oxygen concentration and PDT-induced cellular death, the effects that the ambient fluid flow might have on the concentration of oxygen and PS have been disregarded in many, which limits the reliability of the results. Herein, we coupled the transport of oxygen and PS throughout the ambient medium and within the spheroidal multicellular aggregate to initially study the profiles of oxygen and PS concentration alongside PDT-induced cellular death throughout the spheroid before and after radiation. The attained results indicate that the PDT-induced cellular death initiates on the surface of the spheroids and subsequently spreads to the neighbouring regions, which is in great accordance with experimental results. Afterward, the effects that drug-light interval (DLI), fluence rate, PS composition, microchannel height, and inlet flow rate have on the therapeutic outcomes are studied. The findings show that adequate DLI is critical to ensure uniform distribution of PS throughout the medium, and a value of 5 h was found to be sufficient. The composition of PS is critical, as ALA-PpIX induces earlier cell death but accelerates oxygen consumption, especially in the outer layers, depriving the inner layers of oxygen necessary for PDT, which in turn disrupts and prolongs the exposure time compared to mTHPC and Photofrin. Despite the fluence rate directly influencing the singlet oxygen generation rate, increasing the fluence rate by 189 mW/cm2 would not significantly benefit us. Microwell height and inlet flow rate involve competing phenomena—increasing height or decreasing flow reduces oxygen supply and increases PS “washout” and its concentration.

Cost-Effective Fabrication of Polydimethylsiloxane (PDMS) Microfluidics for Point-of-Care Application

Microfluidics fabrication pertains to the construction of small-scale devices and systems that manipulate and control small volumes of fluids. This process involves precise engineering and manufacturing procedures aimed at designing and producing these devices, which find applications in healthcare, environmental monitoring, and chemical analysis. The present study showcases an inexpensive approach to fabricate microfluidics channels using PDMS biopolymer and soft lithography technique to achieve laminar fluid flow. Initially, a robust and adhesive mold was created by fabricating a master template using several layers of SU-8 5 and SU-8 2015 negative photoresists. Subsequently, PDMS microfluidics channels were replicated and sealed onto a glass substrate through plasma bonding treatment. High-power microscopy images and profilometer analyses demonstrated successful fabrication with minimal deviation from the initial designs and the fabricated devices (less than 0.07 mm, less than 0.6°). Both the SU-8 master template and PDMS replicate displayed average microchannel height values and surface roughness of 100 μm and 0.26 μm or lower, respectively. Additionally, the fluid test confirmed laminar flow without any leakage post plasma oxidation, indicating the completion of an efficient and cost-effective fabrication process.

Optically controlled variable damping system based on PLZT ceramic/ERF in rectangular microchannel

Variable damping control technology based on intelligent materials of electromagnetic excitation has been widely used in the field of (semi-) active vibration control and fluid control. Unfortunately, a major drawback is the electromagnetic noise interference and low response speed. In this paper, a new optically controlled variable damping system based on PLZT ceramic/electrorheological fluid (ERF) is proposed. The mathematical models of the photovoltage generated by PLZT ceramics and the pressure difference between the two ends of the microchannel are established and verified by numerical simulation in COMSOL Multiphysics. Meanwhile, with the increase of light intensity, liquid flow rate and decrease of microchannel height and width, the pressure difference shows an uptrend. Optically controlled variable damping system based on PLZT ceramic/ERF is a control method with the advantages of a clean excitation source, remote control, no electromagnetic interference, and fast response speed, and has a good application prospect in the field of vibration control and fluid control.

Thermal analysis and structure optimization of wavy microchannel with combining ribs of porous layer and solid wall in multi objective genetic algorithm

The combining rib of porous layer and solid wall is set in wavy microchannel heat sink to enlarge heat transfer area and convection with smaller increase in flow resistance, in which the consumption of pump power relates to the ratios of wave amplitude to length or to width and the thickness of porous layer due to vortices generation while coolant passing through channel. The local thermal equilibrium occurs in porous layer, and the Forchheimer-Brinkman-Darcy relations were used to describe the flow inside porous ribs. The effects of channel-to-pitch width ratio, width ratio of porous layer to pitch and microchannel height on its cooling performance are investigated, and the parameter of figure of merit (FOM) is defined to evaluate thermo-hydraulic performance in wavy microchannel. Besides, the multi objective genetic algorithm method is employed to optimize structure parameters in wavy microchannel to obtain better performances, in which the increase in thermal resistance from 0.062 K/W to 0.166 K/W together with consumption of pump power decreasing from 0.00416 W to 0.00185 W can be obtained in the Pareto front set, and it relates to the heat dissipation in convection between coolant and bottom surface or vertical side ribs. Compared to wavy microchannel with solid rib, the 37.61% and 16.67% decreases respectively in thermal resistance and consumption of pump power occur in the case with optimal combining rib of porous layer and solid wall.

Numerical study of microscale gas pump based on surface acoustic waves

The concept of microscale fluidic pump based on microchannel with surface acoustic waves (SAWs), propagating along one of its walls, has been extensively studied in the last decade with possible application to lab-on-chip projects. Meanwhile, any mentions of the application of such device to gas medium seem absent in the literature. The present paper aims to fill this gap by investigating the possibility of using microchannel with SAWs as a microscale gas pump. The numerical study is performed using the modification of the direct simulation Monte Carlo method. It was shown that the pumping effect occurs mainly in the area covered by SAW, while the upper layers of gas are almost still in average. The pumping effect demonstrates weak dependence on gas rarefaction, decreases with the SAW speed, and is lower for a low amplitude to channel height ratios. Finally, it is shown that the propulsion intensity in the open system decreases with a decreasing microchannel height, while the compression ratio in the closed system, on the contrary, increases.

Investigation of geometry-dependent sensing characteristics of microfluidic for single-cell 3D localization.

Flow cytometry-based measurement techniques have been widely used for single-cell characterizations, such as impedance, size, and dielectric properties. However, in the measurement process, the reliability of the output measurement signal directly affects the ability of the microsystem to judge the characteristics of single cells. Here, we designed a multiple nonparallel electrode structure for single-cell 3D localization. The performance of the structures was studied by analyzing the changes in electric field strength and the output differential current. The effects of microchannel height, sensing electrode distance, electrode inclination angle, and electrode width on output signals are investigated by analyzing the current change and electric field strength of single cells passing from the center of the microchannel. The numerical simulation results indicate that, when the microchannel height is 20 µm, the distance of the sensing electrodes is 100 µm, the inclination angle is 30°, the electrode width is 20 µm, and the optimal signal quality can be obtained. Reducing the height of the flow channel and shortening the sensing electrode spacing can significantly improve the signal amplitude. When the channel height is 20 µm, the signal intensity increases by 80% than that of 30 µm. The signal intensity of induced current with the sensing electrode spacing of 100 µm is 42% higher than that with the spacing of 120 µm. We analyzed the presence of multiple independent cells and adherent cells in the detection area and demonstrated through simulation that the signal changes caused by multi-cells can be superimposed by multiple single-cell signals. The induced current signal intensity of the same volume of cells with an ellipticity of 1 is 49% lower than that of cells with an ellipticity of 4. Based on the numerical investigation, we expect that the optimal geometry structure design will aid in the development of better performance signal cell impedance cytometry microsystems.

A Novel Micromixer That Exploits Electrokinetic Vortices Generated on a Janus Droplet Surface.

Micromixers play a crucial role as essential components in microfluidic analysis systems. This paper introduces a novel micromixer designed by harnessing electrokinetic vortices arising on the surface of a Janus droplet within a microchannel. The Janus droplet is characterized by different polarities of charges on its two sides (upstream part and downstream part). In the presence of a direct current electric field, the droplet's surface generates electroosmotic flows in opposite directions, resulting in the formation of vortices and facilitating solution mixing. Results from numerical simulations suggest that a better mixing performance of the micromixer is associated with both a higher absolute value of the zeta potential ratio between the downstream and upstream surfaces of the Janus droplet and a larger downstream surface area. Additionally, this study reveals that microchannel dimensions significantly influence the performance of the micromixer. Smaller microchannel widths and heights correspond to a larger mixing index for the micromixer. The micromixer presented in this study features a simple structure, easy fabrication, and holds promising application potential.

Sensitivity of acoustofluidic particle manipulation to microchannel height in standing surface acoustic wave-based microfluidic devices

In this paper, the flow and particle trajectories, induced by standing surface acoustic waves (SSAWs) in a poly-dimethylsiloxane microchannel, are investigated by establishing a two-dimensional cross-sectional model with the finite element method and improved boundary conditions. Extensive parametric studies are conducted regarding the channel height, ranging from 0.2 to 4.0 times the spacing of the repetitive vertical interference pattern, to investigate its influences on the flow field and microparticle aggregation. The first-order flow field is found to be related to the channel height, exhibiting a periodic spatial distribution and oscillatory variation in its amplitude as the height changes. We theoretically analyze the propagation mechanism of the acoustic waves in the vertical direction and thus determine the periodicity of the wave interference pattern. Furthermore, we find that the speed of the particle aggregation is a function of the channel height, so the channel height can be optimized to maximize the strength of the first-order flow field and thus minimize the time of particle aggregation. The optimum heights can reduce the aggregation time by up to 76%. In addition, the acoustophoretic motions of microparticles exhibit a spatially dependent pattern when the channel height becomes larger than a quarter of the wavelength of the SAW, which can be explained by the change in the ratio between the radiation force and the streaming drag force from position to position. Our findings provide guidelines to the design and optimization of SSAW-based acoustofluidic devices.

Deformation patterns and coordination mechanisms of cross-size microchannels during thermocompression bonding process

High-quality bonding of microfluidic chips is essential for driving the rapid marketization of microfluidic devices. While thermocompression bonding is known for its simplicity, challenges such as high deformation and low bond strength persist. In this paper, we conducted micro-scale compression creep experiments to address the coexistence problem between low deformation and high bond strength during the thermocompression bonding process. Accurate creep models were constructed based on the experimental results, achieving an improved simulation accuracy of 95% for microchannel deformation in thermocompression bonding. Additionally, a finite element simulation model was developed to simulate microchannel deformation during the thermocompression process. To enhance bond strength and minimize microchannel deformation, we propose two methods: microchannel height compensation and cross-size microchannel coordination. Results demonstrate a remarkable 200% improvement in bond strength with reduced microchannel deformation under the same bonding conditions. The findings of this study offer valuable insights and serve as a process reference and design basis for enhancing the quality of microfluidic chip products.

Fabrication of superhydrophobic surface by a dimensional change in surface topography of microchannel on polymer substrate through induction-aided hot embossing: parametric investigation and optimization

Hot embossing (HE) is a micro-fabrication technique employed to create micron-scale patterns on the polymer substrate. An in-house induction-assisted hot embossing (IHE) setup was fabricated to complete the embossing in a short duration as compared to traditional hot embossing process. This work alters the polymer surface topography to make it superhydrophobic for self-cleaning. Fiber laser machining was used to produce four-microchannel designs on an Aluminum-6061 plate in which the microchannel width was varied from 600 μm to 150 μm while maintaining a constant adjacent distance of 300 μm. This textured plate is employed as a mold in the IHE setup. IHE process parameters, embossing temperature, pressure, time, and deembossing temperature were varied to emboss the mold designs on a polyethylene terephthalate substrate. Thereafter, the embossed microchannel height, surface roughness, and water contact angle perpendicular to the embossed microchannels (WCA⟂) were calculated. The parametric analysis examined how operational factors affected the output. The experiment was done as per the central composite design (experimental design) part of the design-of-experiments useful in the response surface model. Parametric research demonstrates that embossed microchannel height and width had a maximum effect on WCA⟂. Type-IV microchannels with 150 μm width demonstrated the highest WCA⟂. The WCA⟂ was mostly impacted by embossed microchannel height; hence a regression model was created using type-IV channel height data. Analysis of variance showed that embossing temperature mainly impacts microchannel height. The recently invented Jaya-algorithm optimized this model to increase embossed microchannel height and WCA⟂. Setting the parameters at the best level predicted by Jaya-algorithm yielded an embossed microchannel height inaccuracy of 2.18%. The WCA⟂ measured on the surface of a sample prepared at the best parameters was found to be 154.71° 2°. Lastly, FTIR (Fourier-transform-infrared-spectroscopy) test showed no chemical composition change between the embossed and bare samples.

The effect of microchannel height on the acoustophoretic motion of sub-micron particles

Acoustophoresis is an effective technique for particle manipulation. Acoustic radiation force scales with particle volume, enabling size separation. Yet, isolating sub-micron particles remains a challenge due to the acoustic streaming effect (ASE). While some studies confirmed the focusing ability of ASE, others reported continuous stirring effects. To investigate the parameters that influence ASE-induced particle motion in a microchannel, this study examined the effect of microchannel height and particle size. We employed standing surface acoustic wave (SSAW) to manipulate polystyrene particles suspended in the water-filled microchannel. The results show that ASE can direct particles as small as 0.31 µm in diameter to the centre of the streaming vortices, and increasing the channel height enhances the focusing effect. Smaller particles circulate in the streaming vortices continuously, with no movement towards the centres. We also discovered that when the channel height is at least 0.75 the fluid wavelength, particles transitioning from acoustic radiation-dominated to ASE-dominated share the same equilibrium position, which differs from the pressure nodes and the vortices’ centres. The spatial distance between particles in different categories can lead to particle separation. Therefore, ASE is a potential alternative mechanism for sub-micron particle sorting when the channel height is accurately adjusted.

Microfluidic fabrication using cyclic olefin copolymer and hydrocarbon solvents

Cyclic olefin copolymer (COC) is a promising material in microfluidic applications due to their unique physical, chemical, and optical properties. This study implements a new and versatile fabrication process to fabricate COC microchannels, combining the fabrication and bonding processes in a single step, taking advantage of COCs’ swelling behavior in linear non-polar hydrocarbon solvents and their chemical compatibility with photolithography. Dodecane was selected as the hydrocarbon solvent based on the degree of swelling and Flory-Huggins interaction parameter, which resulted in the highest degree of swelling and affinity to COC. The effect of dodecane immersion time on the COC microchannel height was investigated, achieving a maximum average height of 50 ± 3 µm after 180 min. Bonding quality was quantified by a leakage test (maximum flow rate of 1730 ± 205 µL/min (Re = 237)), and a tensile test (800 ± 90 kPa). Furthermore, the effectiveness of the implemented process was demonstrated through the successful execution of three highly diverse microfluidic applications. These applications included a serpentine microchannel featuring semicircular obstacles that facilitated passive mixing, pinched flow fractionation which enabled the separation of a system of three different sizes of microparticles, and droplet microfluidics that allowed for the efficient generation of water in oil droplets.

Gas-assisted microfluidic step-emulsification for generating micron- and submicron-sized droplets

Micron- and submicron-sized droplets have extensive applications in biomedical diagnosis and drug delivery. Moreover, accurate high-throughput analysis requires a uniform droplet size distribution and high production rates. Although the previously reported microfluidic coflow step-emulsification method can be used to generate highly monodispersed droplets, the droplet diameter (d) is constrained by the microchannel height (b), dgtrsim 3b, while the production rate is limited by the maximum capillary number of the step-emulsification regime, impeding emulsification of highly viscous liquids. In this paper, we report a novel, gas-assisted coflow step-emulsification method, where air serves as the innermost phase of a precursor hollow-core air/oil/water emulsion. Air gradually diffuses out, producing oil droplets. The size of the hollow-core droplets and the ultrathin oil layer thickness both follow the scaling laws of triphasic step-emulsification. The minimal droplet size attains dapprox 1.7b, inaccessible in standard all-liquid biphasic step-emulsification. The production rate per single channel is an order-of-magnitude higher than that in the standard all-liquid biphasic step-emulsification and is also superior to alternative emulsification methods. Due to low gas viscosity, the method can also be used to generate micron- and submicron-sized droplets of high-viscosity fluids, while the inert nature of the auxiliary gas offers high versatility.

Numerical investigation on flow and heat transfer characteristics in honeycomb-like microchannel heat sink encapsulated with phase change material

The present study proposes a novel model to numerically investigate the flow and heat transfer characteristics of a honeycomb-like microchannel heat sink (MCHS) encapsulated with phase change material (PCM). Compared with a single MCHS, the hybrid MCHS combines the advantages of microchannels in terms of micro efficiency with the isothermal phase change effect of PCM. The finite volume method is used to discretize the three-dimensional flow and heat transfer processes within the hybrid MCHS. Special attentions are paid to the effects of PCM, geometric parameters and local hot spots on the temperature uniformity and flow heat transfer performance. The results show that the honeycomb inflow structure design and the thermal management characteristics of PCM phase change cooling exhibit better temperature uniformity and cooling performance. The overall performance of the heat sink is best at microchannel height of 0.09 mm and inlet number of 5 under the range of parameters studied. Adjusting the channel height from 0.06 mm to 0.09 mm at a volume flow rate of 10 mL∙min−1 can reduce the thermal resistance by 51 % and the pumping power by nearly 20 %. Increasing the number of microchannel inlets results in better heat transfer performance, but this improvement comes at the expense of larger pressure drop. When a local hotspot occurs, the hybrid MCHS can reduce the temperature peak by 2–5 K, achieving a smoother temperature distribution.

Simulation on pool boiling heat transfer considering the integrated effect of engineered microchannels and mixed wettability

Comparing with the abundant experimental investigations on the pool boiling heat transfer, this study aims to explore the integrated effect of engineered microchannels and the mixed wettability on the enhancement in pool boiling heat transfer in a wide range of geometric and physical conditions. A two-dimensional transient volume of fluid (VOF) model was adopted to simulate the bubble behavior and thermal performance on different surfaces including the hydrophilic plain, hydrophilic microchannel, hydrophilic microchannel with hydrophobic top, and hydrophilic microchannel with hydrophobic bottom, respectively. The vapor volume fraction, velocity vector field, temperature of solid/liquid interface, and average heat transfer coefficients (HTCs) on different geometric surfaces were obtained based on the numerical model. It was found that hydrophobic areas are necessary to be added in the hydrophilic channels to facilitate the bubble nucleation and detachment due to the merit of the mixed wettability. However, it is crucial to optimize the width and location of the hydrophobic areas and the height of the hydrophilic microchannel for the prevention of early formation of vapor blanket and promotion of liquid replenishment. With the hydrophobic area on the top of the microchannel, the maximum solid/liquid interface temperature was 392.8 K, which decreased by 0.91 % comparing with that on the hydrophilic microchannel. While with a hydrophobic bottom (W1 = 2 and 4 μm), the max average HTCs were 508.2 kW/(m2K) and 503.5 kW/(m2K), which were 16.4 % and 11.4 % higher than that in hydrophilic microchannel (W1 = 2 and 4 μm), respectively. The simulation results indicate that the microchannel with optimized mixing of the wettability can efficiently promote the bubble to move upward and liquid to rewet along with the hydrophilic wall, forming the separation of vapor–liquid pathways to further enhance pool boiling heat transfer.

Mold Embossing-Based Soft Lithography for Fabrication of Complex Non-rectangular Channels.

This paper demonstrates a simple, flexible, and controllable technique to fabricate complex non-rectangular microchannels through the mold (e.g., balls) embossing-based soft lithography method. The good ductility of aluminum foil ensures the complete replication of the ball morphology, resulting in creation of the microchannels with a perfect circular cross section. By investigating the fabrication parameters such as the gap size and ball diameter, we can precisely control the width and height of the circular microchannel. More importantly, the method can be extended to create more complex channels with a series of cross-sectional shapes or combined channels through replacing the balls to the molds with various cross sections. Finally, the complex non-rectangular channels were designed and utilized to construct microfluidic valves and improve the mixing results of two liquids.

Acoustic Streaming Efficiency in a Microfluidic Biosensor with an Integrated CMUT.

The effect of microchannel height on acoustic streaming velocity and capacitive micromachined ultrasound transducer (CMUT) cell damping was investigated. Microchannels with heights ranging from 0.15 to 1.75 mm were used in experiments, and computational microchannel models with heights varying from 10 to 1800 micrometers were simulated. Both simulated and measured data show local minima and maxima of acoustic streaming efficiency associated with the wavelength of the `bulk acoustic wave excited at 5 MHz frequency. Local minima occur at microchannel heights that are multiples of half the wavelength (150 μm), which are caused by destructive interference between excited and reflected acoustic waves. Therefore, microchannel heights that are not multiples of 150 μm are more favorable for higher acoustic streaming effectiveness since destructive interference decreases the acoustic streaming effectiveness by more than 4 times. On average, the experimental data show slightly higher velocities for smaller microchannels than the simulated data, but the overall observation of higher streaming velocities in larger microchannels is not altered. In additional simulation, at small microchannel heights (10-350 μm), local minima at microchannel heights that are multiples of 150 μm were observed, indicating the interference between excited and reflected waves and causing acoustic damping of comparatively compliant CMUT membranes. Increasing the microchannel height to over 100 μm tends to eliminate the acoustic damping effect as the local minima of the CMUT membrane swing amplitude approach the maximum value of 42 nm, which is the calculated amplitude of the freely swinging membrane under the described conditions. At optimum conditions, an acoustic streaming velocity of over 2 mm/s in a 1.8 mm-high microchannel was achieved.

Ultrasonic Characterization of Ibidi μ-Slide I Luer Channel Slides for Studies With Ultrasound Contrast Agents.

Understanding and controlling the ultrasound contrast agent (UCA)'s response to an applied ultrasound pressure field are crucial when investigating ultrasound imaging sequences and therapeutic applications. The magnitude and frequency of the applied ultrasonic pressure waves affect the oscillatory response of the UCA. Therefore, it is important to have an ultrasound compatible and optically transparent chamber in which the acoustic response of the UCA can be studied. The aim of our study was to determine the in situ ultrasound pressure amplitude in the ibidi μ -slide I Luer channel, an optically transparent chamber suitable for cell culture, including culture under flow, for all microchannel heights (200, 400, 600, and [Formula: see text]). First, the in situ pressure field in the 800- [Formula: see text] high channel was experimentally characterized using Brandaris 128 ultrahigh-speed camera recordings of microbubbles (MBs) and a subsequent iterative processing method, upon insonification at 2 MHz, 45° incident angle, and 50-kPa peak negative pressure (PNP). Control studies in another cell culture chamber, the CLINIcell, were compared with the obtained results. The pressure amplitude was -3.7 dB with respect to the pressure field without the ibidi μ -slide. Second, using finite-element analysis, we determined the in situ pressure amplitude in the ibidi with the 800- [Formula: see text] channel (33.1 kPa), which was comparable to the experimental value (34 kPa). The simulations were extended to the other ibidi channel heights (200, 400, and [Formula: see text]) with either 35° or 45° incident angle, and at 1 and 2 MHz. The predicted in situ ultrasound pressure fields were between -8.7 and -1.1 dB of the incident pressure field depending on the listed configurations of ibidi slides with different channel heights, applied ultrasound frequencies, and incident angles. In conclusion, the determined ultrasound in situ pressures demonstrate the acoustic compatibility of the ibidi μ -slide I Luer for different channel heights, thereby showing its potential for studying the acoustic behavior of UCAs for imaging and therapy.

A hybrid microchannel heat sink with ultra-low pressure drop for hotspot thermal management

Hotspot with several orders of magnitude heat flux higher than the background areas has become a prominent issue in the thermal management of advanced electronics. In this study, a novel microchannel heat sink with ultra-low power consumption has been introduced for chip-level hotspot thermal management. The proposed IM-HM heat sink incorporates rectangular microchannels for the background zone and pin-fins for the hotspot region, configured with an upper inlet and two side outlets. Using maximum temperature, pressure drop, and temperature uniformity as key metrics, a comprehensive numerical analysis of the IM-HM heat sink at different Reynolds number were conducted based on computational fluid dynamics. Our results demonstrate that the IM-HM heat sink enhances local heat transfer capacity and exhibits better temperature uniformity compared to the traditional rectangular microchannel heat sinks. Moreover, incorporating entry chamfer and augmenting the microchannel height have been found to effectively mitigate pressure drop in microfluidic systems. Specifically, simulation results indicate that the pressure drop in the microchannel can be reduced by 63.4 and 72.3% by increasing the inlet chamfer angle and microchannel height to 500 and 1500, respectively. Notably, the optimized IM-HM heat sink yields over 98.4% savings in pumping power to achieve consistent maximum temperatures compared to traditional rectangular microchannel heat sinks, while also exhibiting smaller temperature gradient.