Browsing by Author "Topuz, Alper"
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Item Restricted Bocce sporunun Türkiye’ye gelişi ve gelişimi(Bilkent University, 2017) Çoşkuner, Ege; Demiralp, Berke; Sarı, Burak; Topuz, Alper; Özcan, Faruk Yücel; Uygunca, Vesile BesteItem Open Access Flow rate-controlled pipetting for microfluidics: second-generation flexible hydraulic reservoir (FHRv2)(Springer, 2021-01-04) Atay, Atakan; Topuz, Alper; Sarıarslan, Büşra; Yıldırım, E.; Charmet, J.; Couling, K.; Çetin, BarbarosA critical component of microfluidic technology is the fluid pumping mechanism. Syringe and pressure pumps are typically used in the lab environment; however, their operations generate considerable dead volume that is often larger than the volume of the chip itself, leading to considerable waste of precious sample. As an alternative, pipetting allows for precise liquid dispensing with zero dead volume; however, it has a limited flow control. Recently, we have introduced a low-cost sample loading interface with zero dead-volume named flexible hydraulic reservoir (FHR). In this study, we present a second-generation FHRv2 that combines continuous pumping, zero-dead volume and the versatility of pipetting. The performance of FHRv2 is tested against a syringe pump at flow rates ranging between 20 and 60 μL/min. It demonstrated smoother operation and identical transient time to reach steady flow rate as confirmed by a mathematical model developed for the occasion. Importantly, we also demonstrate that the FHRv2 prevents sedimentation-induced artifacts typically encountered in typical syringe pumps when dispensing particles. Finally, we demonstrate the fabrication of the FHRv2 concept with injection molding using a 3D-printed mold. Overall, our FHRv2 offers a low-cost and versatile solution for zero-volume liquid handling in microfluidic devices.Item Open Access A multi-domain direct boundary element formulation for particulate flow in microchannels(2021-08) Topuz, AlperIn the present study, a multi-domain boundary element formulation is developed for high surface-area-to-volume ratio problems (i.e. particulate flow in high as-pect ratio microfluidic channels, in a porous medium or in microfluidic devices with repetitive structures). The solution domain is decomposed into subdomains and the variable condensation technique is implemented. The solution matrices are built for each subdomain, and the matrices are updated at each time step only for the subdomains in which the particles move at each time step. Ghost domains, which are fictitious domains encapsulating the interfaces between the subdomains, are also introduced in the formulation to treat the particles cross-ing the interfaces between the subdomains. The formulation reveals that the computation of the subdomain matrices is further simplified for solution domains composed of periodic structures. The results of our study revealed that speed-up values as high as 50 for 2D structures and 80 for 3D structures is achievable with the current formulation.Item Open Access A multi-domain direct boundary element formulation for particulate flow in microchannels(Elsevier Ltd, 2021-11-01) Topuz, Alper; Baranoğlu, B.; Çetin, BarbarosIn the present study, a multi-domain boundary element formulation is developed for high surface-area-to-volume ratio problems (i.e. particulate flow in high aspect ratio microfluidic channels, in a porous medium or in microfluidic devices with repetitive structures). The solution domain is decomposed into subdomains and the variable condensation technique is implemented. The solution matrices are built for each subdomain, and the matrices are updated at each time step only for the subdomains in which the particles move at each time step. Ghost domains, which are fictitious domains encapsulating the interfaces between the subdomains, are also introduced in the formulation to treat the particles crossing the interfaces between the subdomains. The formulation reveals that the computation of the subdomain matrices is further simplified for solution domains composed of periodic structures. The results of our study revealed that speed-up values as high as 50 is achievable with the current formulation.