In this study, we present a technique for generation of hydrogel microdroplets as bioink for droplet deposition of tissues and organs. We also characterized the size and dispersion of the microdroplets. For this purpose, we designed a flow-focusing droplet generator chip in which uncured hydrogel flowing through a 120 µm wide channel was pinched at two sides of the stream of oil flowing along 300 µm wide channels. The chip was fabricated by ultrasonically embossing the features on polymethylmethacrylate (PMMA) plate. We used polyethylene (glycol) diacrylate (PEGDA) as the hydrogel and silicone oil as the pinching fluid. PEGDA was preferred since it provides an inherently inert matrix for cell growth. Before dispensing the liquids into the chip, PEGDA was mixed with photoinitiator (Irgacure 2959) to make PEGDA curable under UV exposure. The results showed that PEGDA droplets of 7419 µm diameter could be generated with average dispersion of 42762 µm between two successive droplets at a rate of about 600 Hz. After generating, droplets were cured in the chip by exposing under UV light for 1 minute. We have shown that single cells could be encapsulated in hydrogel microdroplets.


Computer simulation of grain boundary grooving by anisotropic surface drift diffusion due to capillary, electromigration and elastostatic forces
Akyıldız, Öncü; Oğurtanı, Tarık Ö.; Department of Metallurgical and Materials Engineering (2010)
The aim of this study is to develop a theoretical basis and to perform computational experiments for understanding the grain boundary (GB) grooving in polycrystalline thin film metallic conductors (interconnects) by anisotropic surface diffusion due to capillary, electromigration and elastostatic forces. To this end, irreversible thermo–kinetics of surfaces and interfaces with triple junction singularities is elaborated, and the resulting well-posed moving boundary value problem is solved using the front–tr...
Analytical solution of a crack problem in a radially graded FGM
Çetin, Suat; Kadıoğlu, Fevzi Suat; Department of Mechanical Engineering (2007)
The objective of this study is to determine stress intensity factors (SIFs) for a crack in a radially graded FGM layer on a substrate. Functionally graded coating with an edge crack perpendicular to the interface and a homogeneous substrate are bonded together. In order to make the problem analytically tractable, geometry is modeled as an FGM strip attached to a homogeneous layer. Introducing the elastic foundation underneath the homogeneous layer, an FGM coating on a thin walled cylinder can be modeled. At...
Fabrication and characterization of p-Si/n-ZnO heterostructured junctions
Klason, P.; Rahman, M. M.; Hu, Q. -H.; Nur, O.; Turan, Raşit; Willander, M. (Elsevier BV, 2009-04-01)
In this paper ZnO nanorods and nanodots (with and without a SiO2 buffer layer) were grown on p-Si, forming p-n heterojunctions. The nanorod devices showed no visible electroluminescence (EL) emission but showed rectifying behavior. Covering around 60% of the length of the nanorods with PMMA produced an ideality factor of 3.91 +/- 0.11 together with a reverse saturation current of 6.53 +/- 4.2 x 10(-8) A. Up to two orders of magnitude rectification was observed for the current at bias -3 and 3 V. The nanodot...
High resolution imaging of anisotropic conductivity with magnetic resonance electrical impedance tomography (mr-eit)
Değirmenci, Evren; Eyüboğlu, Behçet Murat; Department of Electrical and Electronics Engineering (2010)
Electrical conductivity of biological tissues is a distinctive property which differs among tissues. It also varies according to the physiological and pathological state of tissues. Furthermore, in order to solve the bioelectric field problems accurately, electrical conductivity information is essential. Magnetic Resonance Electrical Impedance Tomography (MREIT) technique is proposed to image this information with high spatial resolution. However, almost all MREIT algorithms proposed to date assumes isotrop...
Three dimensional fracture analysis of FGM coatings
İnan, Özgür; Dağ, Serkan; Department of Mechanical Engineering (2004)
The main objective of this study is to model the three dimensional surface cracking problem in Functionally Graded Material (FGM) coatings bonded to homogeneous substrates. The FGM coating is assumed to be a (ZrO2) ا (Ti-6Al-4V) layer. Homogeneous ceramic, metal ا rich, ceramic ا rich and linear variation material compositions are considered in the analyses. The surface crack is assumed to have a semi ا circular crack front profile. The surface crack problem in the FGM coating ا substrate system is examined...
Citation Formats
F. Sucularlı, E. Yıldırım, and M. A. S. Arıkan, “GENERATION AND CHARACTERIZATION OF HYDROGEL MICRODROPLETS AS BIOINK FOR BIOPRINTING APPLICATIONS,” Antalya, Türkiye, 2019, p. 416, Accessed: 00, 2021. [Online]. Available: