Shahrekord UniversityJournal of Microfluidic and Nanofluidic Research2120250301Micromixing of Blood Plasma and DI water in a Passive Micromixer48541180510.22034/jmnr.2025.15162.1006ENHaneen Ahmed SahibAl-HachamiDepartment of Mechanical Engineering, Shahrekord University, Shahrekord, IranMortezaBayarehDepartment of Mechanical Engineering, Shahrekord University, Shahrekord, IranAhmad RezaSajadi DehkordiDepartment of Mechanical Engineering, Shahrekord University, Shahrekord, IranJournal ArticleMicromixers are important devices in microfluidics designed for mixing liquids on a micro scale. These devices are crucial in chemistry, pharmaceuticals, analytical chemistry, biochemistry, and high-throughput synthesis due to their ability to manage small volumes of liquids with precision. In the present work, the mixing process in a converging-diverging micromixer is examined. The micromixer has three mixing units, each consisting of a chamber and an obstacle. For the reference case without an obstacle, molecular diffusion causes mixing at the interface of the two fluids, and with an increase in the number of mixing units and fluid advancement, the effect of molecular diffusion becomes more pronounced. It is also observed that with an increase in input velocity, the mixing index also increases. In the first case, the formation of vortices behind the obstacle leads to greater mixing of the two liquids. Compared to the reference case, the mixing index of the first case increases from 19.12% to 30.21% at an inlet velocity of 0.001 m/s. In the second case, unlike the first one, the maximum mixing index occurs at the lowest inlet velocity. The mixing index for the first and third cases is 34.26% and 56.24%, respectively. However, the pressure drop also increases from 48220 Pa to 58807 Pa. In the fourth case, square obstacles do not significantly increase efficiency, and its efficiency is higher than that of the reference case and lower than that of the other cases.https://jmnr.sku.ac.ir/article_11805_13ec9935e17e00bed6ec8f06230e33a9.pdfShahrekord UniversityJournal of Microfluidic and Nanofluidic Research2120250301Numerical Study of an Electroosmotic Micromixer55591180610.22034/jmnr.2025.15164.1007ENAhmadNajafpourDepartment of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, IranNargesJafari GhahfarokhiDepartment of Mechanical Engineering, University of Isfahan, Isfahan, IranJournal ArticleElectroosmotic micromixers utilize electroosmotic flow to enhance fluid mixing at the microscale, which is particularly beneficial in biochemical applications requiring rapid mixing of multiple fluid streams. This study examines an asymmetric electroosmotic micromixer to assess the impact of inlet velocity and applied voltage on the mixing index (MI) and pressure drop (Δp). The results show that the applied voltage significantly improves mixing quality while having a minimal effect on Δp. For instance, when the inlet velocity (Uin) is 0.2 mm/s, increasing the applied voltage from 0 to 6 V boosts the MI from 64.61% to 67.66%. At Uin = 0.8 mm/s, this enhancement is more pronounced, with the MI rising from 65.92% to 85.55%. Additionally, the study reveals that the MI increases with inlet velocity for a given applied voltage.https://jmnr.sku.ac.ir/article_11806_ea0d1687bc7b27bc6b5b34bc88f1b5dd.pdfShahrekord UniversityJournal of Microfluidic and Nanofluidic Research2120250301Effect of Inlet Velocity and Voltage on the Mixing Performance of an Electroosmotic Device60641180710.22034/jmnr.2025.15166.1008ENNargesJafari GhahfarokhiDepartment of Mechanical Engineering, University of Isfahan, Isfahan, IranAhmadNajafpourDepartment of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, IranJournal ArticleElectroosmotic micromixers are utilized in microfluidic systems, especially in biochemical studies. This article examines an asymmetric electroosmotic micromixer to ascertain the effects of applied voltage and inlet velocity (Uin) on mixing index (MI) and pressure drop (Δp). It is shown that without altering Δp, the applied voltage greatly increases MI. For instance, when Uin= 0.2 mm/s, increasing the applied voltage from 0 to 1, 3, and 6 V improves MI by 2.31%, 2.53%, and 5.47%, respectively. MI is improved by 2.76%, 3.66%, and 8.38%, respectively, when the applied voltage is increased from 0 to 1, 3, and 6 V with Uin= 0.4 mm/s. MI is improved by 2.86%, 5.08%, and 11.81%, respectively, when the applied voltage is increased from 0 to 1, 3, and 6 V when Uin= 0.6 mm/s. MI is improved by 3.97%, 6%, and 13.22%, respectively, when the applied voltage is increased from 0 to 1, 3, and 6 V with Uin= 0.8 mm/s. For a given applied voltage, it is seen that Δp increases slightly when the inlet velocity is raised; also, Δp is an increasing function of the applied voltage for a given inlet velocity, despite the little increase.https://jmnr.sku.ac.ir/article_11807_13c86fac19a52dbc843105b709dc71fc.pdfShahrekord UniversityJournal of Microfluidic and Nanofluidic Research2120250301Entropy Analysis in a Heat Sink with Laminar Fluid Flow Regime: A Numerical Investigation65711180810.22034/jmnr.2025.15169.1009ENAhmadNajafpourDepartment of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, IranAlirezaKhaliliDepartment of Energy Engineering, Sharif University of Technology, Tehran, IranJournal ArticleThermal management in electrical appliances has a great impact on their performance and can reduce energy consumption. Heat sinks are an effective tool for cooling electrical equipment that can be used. In the present work, the entropy generation at Reynolds numbers (Re) = 200 to 1000 for 5 configurations of heat sinks with a constant heat flux of 20 kW/m2 has been investigated, which can be effective in reducing the temperature of electrical devices. The results obtained show that with increasing Re, the amount of entropy generated due to fluid flow (Sp) is increased and the amount of entropy generated due to heat transfer (St) is decreased, and finally, increasing Re reduces entropy generation and improves system performance. At Re = 200, the St for Case 4 is decreased by 59.86%, 41.83%, 2.45%, and 2.74%, respectively, compared to the base case, Case 1, Case 2, and Case 3. At Re = 1000, the amount of Na in Case 1, Case 2, Case 3, and Case 4 is decreased by 33.36%, 53.47%, 53.97%, and 55.66%, respectively.https://jmnr.sku.ac.ir/article_11808_6425d167c06fe773378b10b546b6e923.pdfShahrekord UniversityJournal of Microfluidic and Nanofluidic Research2120250301Manipulation of Magnetic Microrobots: A Short Review72771180910.22034/jmnr.2025.15170.1010ENNastaranFarajiDepartment of Mechanical Engineering, University of Isfahan, Isfahan, IranJournal ArticleFor accessing and modifying microscale surroundings, magnetic microrobots have shown great promise, especially in healthcare applications. These robots provide accurate navigation and untethered operation by using magnetic fields for propulsion and control. Different propulsion mechanisms, including torque-driven and force-driven systems, as well as creative manufacturing approaches that improve their biocompatibility and performance, are examples of recent developments in magnetic microrobot design. Targeted medication delivery and microsurgery have demonstrated great promise for biohybrid magnetic microrobots, which combine biological entities with magnetic components. This paper analyzes the state of magnetic microrobots, emphasizing their actuation techniques, design approaches, and biomedical applications. Additionally, it presents the challenges and potential paths forward in this area, highlighting how magnetic microrobots might revolutionize microscale manipulation and medical procedures.https://jmnr.sku.ac.ir/article_11809_d7ead5493404dfc648694a5793608bdf.pdfShahrekord UniversityJournal of Microfluidic and Nanofluidic Research2120250301Effect of Fin Arrangement on Heat Sink Performance: Entropy Analysis78841181010.22034/jmnr.2025.15173.1011ENAlirezaKhaliliDepartment of Energy Engineering, Sharif University of Technology, Tehran, IranMelikaFarazandehSchool of Life Science Engineering, College of Interdisciplinary Science & Technology, University of Tehran, Tehran, IranJournal ArticleWith the growing demand for compact high-performance electronic devices, effective thermal management has become increasingly critical. This study numerically investigates entropy generation and hydrothermal performance in copper-based mini-channel heat sinks (MCHSs) featuring various fin configurations under laminar flow conditions. Five geometrical designs were simulated using COMSOL Multiphysics at Reynolds numbers between 300 and 600 under a constant heat flux of 20 kW/m². Key parameters such as pressure drop, bottom surface temperature, and entropy generation due to heat transfer and fluid friction were analyzed. The results show that finned configurations significantly improve heat dissipation and reduce entropy generation. Among them, Case 4 achieved the best performance, reducing the augmented entropy generation value by up to 56.27% at Re = 300 compared to the base case.https://jmnr.sku.ac.ir/article_11810_ebdc056de8b5669b744b8589add41f8c.pdf