# Experimental Study on Multi-Cell Counting Using an Inertial Microfluidic Device
###### Abstract  
Inertial microfluidics has gained significant attention for cell counting applications due to its simplicity, high throughput, and precision. This study utilized an inertial flow microfluidic device to count blood cell-sized microparticles, simulating normal and diseased conditions. The device could focus on and count cells sized between 7 \(\upmu\)m and 16 \(\upmu\)m while being observed under optical microscopes, with controlled flow rates from 1 to 15 \(\upmu\)L/min. Suspensions of cells with ratios of 600:1 for normal conditions and 400:1 for diseased conditions were studied in microchannels at different flow rates. The methodology for counting involved using a syringe pump for precise flow actuation and employing an image-based particle counting technique through optical microscopy, utilizing the passive technique of inertial microfluidics. Results were compared using two optical microscopes across both suspension types. The key findings showed that at a 600:1 ratio of 8 \(\upmu\)m and 15 \(\upmu\)m cells, counts of 6.45 \(\times\) 10\({}^{7}\) cells/mL and 1.10 \(\times\) 10\({}^{7}\) cells/mL, respectively, while in the 400:1 ratio of both cells, counts of 4.5 \(\times\) 10\({}^{7}\) cells/mL and 2.16 \(\times\) 10\({}^{7}\) cells/mL, respectively, were achieved at optimal parameters. This study employed an inertial flow microfluidic device to count microparticles the size of blood cells. We assessed the counting performance using optical microscopy at two different cell ratios and validated our results against hemocytometer counts. Our findings demonstrate that the channel size 150 \(\upmu\)m and the flow rate at 1 \(\upmu\)L/min provided the optimal counting accuracy for both particle sizes. This device offers an efficient and adaptable solution for accurate multi-cell counting under optimized conditions and supporting applications in resource-limited medical diagnostics. c 2025155701 10390/20251505701 1039 cell counts are indicative of patient health [2]. For instance, fluctuations in white blood cell counts are common in diseases such as malaria, viral infections, and typhoid, which are prevalent in many resource-limited settings [3]. In such scenarios, microfluidic devices offer a rapid and accurate means of performing cell counts, enabling prompt diagnosis and monitoring [4]. Microfluidic devices operate with precision, manipulating small fluid volumes through carefully designed microstructures [5]. The controlled environment within these devices enables the effective analysis of minimal sample volumes, leading to accurate diagnostics with reduced material costs. Their high sensitivity, low operational costs, and suitability for resource-limited settings have made them particularly valuable in healthcare [6]. Cell counting and sorting in microfluidics can be broadly categorized into active and passive techniques. Active techniques like dielectrophoresis (DEP), magnetophoresis, acoustophoresis, and optical tweezers manipulate cells using external force fields [7]. While they offer high resolution and real-time adjustability, they often require complex external setups and have limited throughput due to the need to overcome hydrodynamic drag [8]. Passive techniques, on the other hand, leverage channel geometries and intrinsic hydrodynamic forces for cell manipulation including methods like microscale filtration, pinched flow fractionation, deterministic lateral displacement, and inertial microfluidics [9]. These methods are generally simpler, more robust, and capable of higher throughput, making them suitable for diverse applications [10]. Several techniques for cell counting in microfluidic systems have been developed, including impedance-based cell counting, which leverages the electrical properties of cells for detection and quantification [11]. However, this method's accuracy can be influenced by factors such as the cell size, shape, and internal composition, and scaling it for a wide range of cell concentrations presents challenges. [PERSON] et al.