Browsing by Author "Puttaswamy, Srinivasu Valagerahally"

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DIELECTROPHORETIC CONCENTRATOR FOR ENHANCED PERFORMANCE OF POLY-SILICON NANOWIRE FIELD EFFECT TRANSISTOR FOR BIOSENSING APPLICATION
(2012)
Puttaswamy, Srinivasu Valagerahally
;
Su, Yi-, Jr.
;
Sivashankar, Shilpa
;
Yang, Shih-Mo
;
Yang, Yuh-Shyong
Biological and medical fields have authenticated stupendous advancement in the development of biosensors and biochips. The development of highly sensitive biological sensors is need of the hour. This research work utilizes the dielectrophoretic concentrator chip with titanium (Ti) electrodes to shape the electric field, to pre-concentrate deoxyribo nucleic acid (DNA) within microfluidic channel onto nanowire region of poly-silicon nanowire field effect transistor (poly-Si NWFET). Preconcentration of biomolecules at the constriction site was demonstrated by focusing the DNA with negative dielectrophoresis (nDEP) manipulation technique. After integrating the DEP device with poly-Si NWFET, the I-V-G curve was plotted to ensure n-type behavior.
Electrodeless dielectrophoretic concentrator for analyte pre-concentration on poly-silicon nanowire field effect transistor
(2013-03-01)
Puttaswamy, Srinivasu Valagerahally
;
Lin, Chih-Heng
;
Sivashankar, Shilpa
;
Yang, Yuh-Shyong
;
Liu, Cheng-Hsien
The sensitivity of biosensors can be affected by mass transport limitations as a result of miniaturization. To enhance signal sensitivity, pre-concentration of deoxyribonucleic acid (DNA), in the vicinity of the sensing elements of n-type polycrystalline silicon nanowire field effect transistor (Poly-Si NWFET) is demonstrated using a microfluidic device based on insulator or gradient dielectrophoresis (iDEP) to overcome mass transport limitations. In insulator-based dielectrophoresis (iDEP), insulating microstructures produce non-uniform electric fields to drive dielectrophoresis (DEP) in microsystems. Fabrication of accurately controlled three-dimensional (3D) microstructure of poly (ethylene glycol) diacrylate (PEG-DA) with a narrow microchannel using maskless gray-scale lithography is described. The fabrication of three-dimensional structures at low cost with saving time is accomplished by the use of maskless exposure system. PEG-DA has been used due to its excellent biocompatibility and ease of fabrication. To enhance the stability of PEG-DA, we added another polymer pentaerythritol tetraacrylate (PETA). Electrical property of the Poly-Si NWFET is ensured by plotting I-V-G curve after the integration of iDEP micro device. (c) 2013 Elsevier B.V. All rights reserved.
EMULATED CIRCULATORY SYSTEM INTEGRATED WITH LOBULE-MIMETIC LIVER TO ENHANCE THE LIVER FUNCTION
(2012)
Sivashankar, Shilpa
;
Puttaswamy, Srinivasu Valagerahally
;
Dai, Tz-Shuian
;
Lin, Ciou-Wun
;
Yang, Shih-Mo
In the proposed paper, we report dielectrophoresis (DEP) liver lab chip integrated with Poly ethylene glycol diacrylate (PEGDA) based blood vessel within the microfluidic system for reconstructing the engineered liver tissue with the feature of liver function enhancement. The titanium (Ti) electrodes are well designed to provide positive dielectrophoresis (pDEP) and negative dielectrophoresis (nDEP) force to pattern HepG2 and 3T3 fibroblast cells. To mimic the blood flow direction of the liver lobule in vivo, we have integrated the reconstructed liver lobule with hydrogel encapsulated blood vessel. As smooth muscle cells and endothelial cells are the main components of blood vessel, we have utilized these cells and encapsulated within PEGDA hydrogel to mimic blood vessels. When assayed for urea concentration in cultured medium for five time points, the trend illustrated the enhanced metabolism of hepatocytes via blood vessel integrated lobule-mimetic pattern.