Prof. Vamsy P. Chodavarapu Profile

Prof. Vamsy P. Chodavarapu

Professor at Univ of Dayton

SPIE Involvement:

Author

Publications (25)

SPIE Journal Paper | 9 September 2016

Ultraclean wafer-level vacuum-encapsulated silicon ring resonators for timing and frequency references

George Xereas, Vamsy Chodavarapu

JM3, Vol. 15, Issue 03, 035004, (September 2016) https://doi.org/10.1117/12.10.1117/1.JMM.15.3.035004

KEYWORDS: Resonators, Semiconducting wafers, Silicon, Microelectromechanical systems, Polarization, Wafer bonding, Packaging, Etching, Resistance, Microfabrication

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Proceedings Article | 27 August 2014 Paper

Nanocrystalline cellulose for optical encryption

Yu Ping Zhang, Karen Allahverdyan, Timothy Morse, Vamsy Chodavarapu, Andrew Kirk, Tigran Galstian, Mark Andrews

Proceedings Volume 9172, 91720R (2014) https://doi.org/10.1117/12.2062974

KEYWORDS: Reflection, Diffraction gratings, Ultraviolet radiation, Reflectivity, Molecules, Luminescence, Solids, Adhesives, Polarization, Polymer thin films

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Proceedings Article | 7 March 2014 Paper

Design of active temperature compensated composite free-free beam MEMS resonators in a standard process

George Xereas, Vamsy Chodavarapu

Proceedings Volume 8973, 89730N (2014) https://doi.org/10.1117/12.2036239

KEYWORDS: Resonators, Microelectromechanical systems, Gold, Composites, Silicon, Temperature metrology, Electrodes, Thermal effects, Silica, Finite element methods

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Proceedings Article | 7 March 2014 Paper

Design and fabrication of three-axis accelerometer sensor microsystem for wide temperature range applications using semi-custom process

A. Merdassi, Y. Wang, G. Xereas, V. Chodavarapu

Proceedings Volume 8973, 89730O (2014) https://doi.org/10.1117/12.2037344

KEYWORDS: Sensors, Capacitance, Temperature metrology, Microsystems, Silicon carbide, Californium, Transistors, Resistors, Amorphous silicon, Sputter deposition

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SPIE Journal Paper | 2 July 2012

Nanocrystalline cellulose for covert optical encryption

Yu Ping Zhang, Vamsy Chodavarapu, Andrew Kirk, Mark Andrews

JNP, Vol. 6, Issue 01, 063516, (July 2012) https://doi.org/10.1117/12.10.1117/1.JNP.6.063516

KEYWORDS: Ultraviolet radiation, Solids, Particles, Luminescence, Computer security, Reflection, Optical microscopy, Circular polarizers, Molecules, Optical activity

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Proceedings Article | 18 February 2012 Paper

Nanocrystalline cellulose for covert optical encryption

Yu Ping Zhang, Vamsy Chodavarapu, Andrew Kirk, Mark Andrews

Proceedings Volume 8258, 825808 (2012) https://doi.org/10.1117/12.906770

KEYWORDS: Ultraviolet radiation, Solids, Luminescence, Reflection, Particles, Dichroic materials, Optical microscopy, Computer security, Circular polarizers, Optical activity

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Proceedings Article | 15 February 2012 Paper

A study of a self diagnostic platform for the detection of A2 biomarker for Leishmania donovani

Philip Roche, Maurice Cheung, Mohamed Najih, Laura-Isobel McCall, Ibrahim Fakih, Vamsy Chodavarapu, Brian Ward, Momar Ndao, Andrew Kirk

Proceedings Volume 8229, 82290C (2012) https://doi.org/10.1117/12.910146

KEYWORDS: Plasmonics, Polymers, Luminescence, Calibration, Diagnostics, Gold, Proteins, Pathogens, Microfluidics, Nanorods

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Proceedings Article | 2 February 2012 Paper

Optical mapping by low-cost instrumentation and disposable chemically induced nanochannels

Philip Roche, Maurice Cheung, Lenore Beitel, Mark Trifiro, Vamsy Chodavarapu, Andrew Kirk

Proceedings Volume 8231, 82310K (2012) https://doi.org/10.1117/12.910138

KEYWORDS: Microscopes, Capillaries, Genetics, Polymers, Luminescence, Ultraviolet radiation, Tissues, Cancer, Molecules, Ions

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Proceedings Article | 2 February 2012 Paper

A nanorod polymer micro-array formed by micro-contact printing

Philip Roche, Songzhe Wang, Maurice Cheung, Vamsy Chodavarapu, Andrew Kirk

Proceedings Volume 8231, 82310O (2012) https://doi.org/10.1117/12.910142

KEYWORDS: Polymers, Luminescence, Silicon, Gold, Glasses, Plasmonics, Printing, Surface plasmons, Plasmons, Nanorods

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Proceedings Article | 12 February 2011 Paper

Demonstration of a reusable plasmonic polymer microarray sensing platform

Philip J. R. Roche, Maurice Cheung, Songzhe Wang, Behnam Banan, Vamsy Chodavarapu, Andrew Kirk

Proceedings Volume 7908, 79080P (2011) https://doi.org/10.1117/12.878848

KEYWORDS: Polymers, Plasmonics, Refractive index, Surface plasmons, Aluminum, Reflectivity, Ultraviolet radiation, Nanoparticles, Chemical elements, Gold

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Proceedings Article | 2 February 2011 Paper

Origin of iridescence in chiral nematic phase nanocrystalline cellulose for encryption and enhanced color

Yu Ping Zhang, Vamsy Chodavarapu, Andrew Kirk, Mark Andrews, Melodie Carluer, Gilles Picard

Proceedings Volume 7955, 79550V (2011) https://doi.org/10.1117/12.881492

KEYWORDS: Particles, Diffraction, Diffraction gratings, Liquid crystals, Microfluidics, Refractive index, Silica, Microscopes, Polarizers, Crystals

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SPIE Journal Paper | 1 January 2011

Controlling optical properties and surface morphology of dry etched porous silicon

Maurice Cheung, Philip Roche, Mohamad Hajj-Hassan, Andrew Kirk, Zetian Mi, Vamsy Chodavarpu

JNP, Vol. 5, Issue 01, 053503, (January 2011) https://doi.org/10.1117/12.10.1117/1.3571270

KEYWORDS: Silicon, Etching, Reflectivity, Scanning electron microscopy, Optical properties, Semiconducting wafers, Dry etching, Scattering, Interfaces, Oxides

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SPIE Journal Paper | 1 January 2011

Errata: Controlling optical properties and surface morphology of dry etched porous silicon

Andrew Kirk, Maurice Cheung, Philip Roche, Mohamad Hajj-Hassan, Zetian Mi, Vamsy Chodavarapu

JNP, Vol. 5, Issue 01, 050102, (January 2011) https://doi.org/10.1117/12.10.1117/1.3592487

SPIE Journal Paper | 1 November 2010

Enhancement of luminescent quenching based oxygen sensing by gold nanoparticles: comparison between luminophore:matrix:nanoparticle thin films on glass and gold coated substrates

Philip Roche, Maurice Cheung, Lei Yao, Andrew Kirk, Vamsy Chodavarapu

JNP, Vol. 4, Issue 01, 043521, (November 2010) https://doi.org/10.1117/12.10.1117/1.3526729

KEYWORDS: Gold, Nanoparticles, Glasses, Luminescence, Thin films, Oxygen, Sensors, Sol-gels, Signal to noise ratio, Surface plasmons

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Proceedings Article | 23 September 2010 Paper

Dry etch fabrication of ultra-thin porous silicon membranes

Mohamad Hajj-Hassan, Maurice Cheung, Vamsy Chodavarapu

Proceedings Volume 7750, 77501E (2010) https://doi.org/10.1117/12.870979

KEYWORDS: Silicon, Etching, Dry etching, Translucency, Opacity, Scanning electron microscopy, Transmittance, Fabrication, Xenon, Silicon films

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Proceedings Article | 16 September 2010 Paper

Enhancement in sensitivity and detection of luminescent quenching based oxygen sensing by gold nanoparticles

Maurice C.-K. Cheung, Philip J. R. Roche, Lei Yao, Andrew Kirk, Vamsy Chodavarapu

Proceedings Volume 7750, 775006 (2010) https://doi.org/10.1117/12.871036

KEYWORDS: Oxygen, Sol-gels, Nanoparticles, Signal to noise ratio, Gold, Luminescence, Sensors, Surface plasmons, Glasses, Sensing systems

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SPIE Journal Paper | 1 July 2010

Porous silicon and porous polymer substrates for optical chemical sensors

Mohamad Hajj-Hassan, Sung Jin Kim, Maurice Cheung, Lei Yao, Vamsy Chodavarapu, Alexander Cartwright

JNP, Vol. 4, Issue 01, 043513, (July 2010) https://doi.org/10.1117/12.10.1117/1.3472237

KEYWORDS: Silicon, Polymers, Sensors, Oxygen, Etching, Reflection, Polymeric sensors, Luminescence, Scanning electron microscopy, Reflectivity

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Proceedings Article | 13 February 2010 Paper

Dry etched nanoporous silicon substrates for optical biosensors

Mohamad Hajj-Hassan, Maurice Cheung, Vamsy Chodavarapu

Proceedings Volume 7574, 75740Q (2010) https://doi.org/10.1117/12.843712

KEYWORDS: Silicon, Etching, Silicon films, Oxygen, Sensors, Semiconducting wafers, Photoresist materials, Dry etching, Luminescence, Reflectivity

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SPIE Journal Paper | 1 July 2009

Reinforced silicon neural microelectrode array fabricated using a commercial MEMS process

Mohamad Hajj-Hassan, Vamsy Chodavarapu, Wissam Musallam

JM3, Vol. 8, Issue 03, 033011, (July 2009) https://doi.org/10.1117/12.10.1117/1.3184795

KEYWORDS: Electrodes, Silicon, Brain, Tissues, Microelectromechanical systems, Semiconducting wafers, Chromium, Metals, Interfaces, Microfabrication

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Proceedings Article | 16 February 2009 Paper

Enabling intelligent readout of luminescent signals from nanoscale biochemical sensors

Lei Yao, Ka Yi Yung, Vijay Tripathi, Vamsy Chodavarapu, Alexander Cartwright, Frank Bright

Proceedings Volume 7188, 71880E (2009) https://doi.org/10.1117/12.816026

KEYWORDS: Sensors, Luminescence, CMOS sensors, Signal processing, Oxygen, Imaging systems, Signal detection, Digital electronics, Intelligent sensors, Phototransistors

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The development of intelligent miniaturized biochemical sensors has been an area of active research over the past several years. These microsensors and sensor microarrays are finding niche applications in point-of-care diagnostics, personal care, food safety, and environmental monitoring. Among these sensors, optical (luminescence) sensing holds a great promise towards implementing simple, specific, and highly sensitive biochemical sensors. It is generally understood that biochemical recognition elements that respond specifically to the target analytes play a critical role in the overall sensor operation. Aside from the recognition elements, signal detection and processing components are important to collect the information provided by recognition elements and output an easily understandable response. The signal processing component provides the best opportunity to incorporate intelligence to achieve low-power, adaptive, accurate, and reliable sensors. We deal with sensors that use sol-gel derived xerogels as recognition materials and Complementary Metal-Oxide Semiconductor (CMOS) integrated circuits for signal detection and processing. Xerogels are nano/microporous glasses that can be used to encapsulate luminophores, enzymes, and nanoparticles in their pores. In this Article, we will describe some of the emerging integrated sensor platforms that are based on monitoring the excited-state luminescence intensity and lifetimes of the luminophores housed in the xerogels. Specifically, we describe a CMOS imaging system for simultaneously monitoring xerogels sensor arrays. Next, we describe a non-linear phase luminometric system with enhanced and dynamically tunable sensitivity and improved signal-to-noise performance. Finally, we will describe time-based signal processing that could enable the direct measurement of excited state fluorescence lifetimes. This time-to-digital converter requires simple circuit implementation and can be used to measure lifetimes that are on the order of several hundred nanoseconds. The time based signal processing could ultimately allow the development of low-cost lifetime imaging system wherein one could take the lifetimes' image of an array of recognition elements rather than collecting an image of their fluorescence intensities.

Proceedings Article | 13 February 2009 Paper

Brain machine interfaces combining microelectrode arrays with nanostructured optical biochemical sensors

Mohamad Hajj-Hassan, Timothy Gonzalez, Ebrahim Ghafer-Zadeh, Vamsy Chodavarapu, Sam Musallam, Mark Andrews

Proceedings Volume 7188, 718805 (2009) https://doi.org/10.1117/12.808032

KEYWORDS: Sensors, Waveguides, Oxygen, Brain, Electrodes, Polymers, Polymer multimode waveguides, Silicon, Sol-gels, Epoxies

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Proceedings Article | 22 February 2008 Paper

Direct-write patterning of nanostructured sensory waveguides for integrated optical bioimaging applications

Mohamad Hajj-Hassan, Timothy Gonzalez, Hagop Djeghelian, Ebrahim Ghafar-Zadeh, Daniel Therriault, Vamsy Chodavarapu, Mark Andrews

Proceedings Volume 6865, 686504 (2008) https://doi.org/10.1117/12.763965

KEYWORDS: Waveguides, Sensors, Oxygen, Epoxies, Microfluidics, Fabrication, Nanostructuring, Optical lithography, Sol-gels, CMOS sensors

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Proceedings Article | 12 February 2007 Paper

Nanostructured porous polymeric photonic bandgap structures for sensing

Sung Jin Kim, Vamsy Chodavarapu, Rachel Bukowski, A. Titus, Alexander Cartwright, Mark Swihart, Frank Bright, Timothy Bunning

Proceedings Volume 6447, 64470O (2007) https://doi.org/10.1117/12.716666

KEYWORDS: Sensors, Polymers, Chemical elements, Oxygen, Luminescence, Polymeric sensors, Structural sensing, Reflection, Glucose, Optical sensors

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Proceedings Article | 30 August 2006 Paper

Tunable porous photonic bandgap structures for chemical and biological sensing

Sung Jin Kim, Vamsy Chodavarapu, Firdous Kamal, Vincent Hsiao, Alexander Cartwright, Mark Swihart, Paras Prasad, Timothy Bunning

Proceedings Volume 6322, 632201 (2006) https://doi.org/10.1117/12.681356

KEYWORDS: Polymers, Sensors, Reflection, Liquid crystals, Holography, Chemical elements, Luminescence, Glasses, Silicon, Prisms

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Proceedings Article | 28 February 2006 Paper

CMOS-based biosensor systems using integrated nanostructured recognition elements

Vamsy Chodavarapu, Daniil Shubin, Rachel Bukowski, Elizabeth Tehan, Albert Titus, Alexander Cartwright, Frank Bright

Proceedings Volume 6095, 60950O (2006) https://doi.org/10.1117/12.649907

KEYWORDS: Sensors, CMOS sensors, Glucose, Luminescence, Light emitting diodes, Microsystems, Nanostructuring, Signal detection, Phase shifts, Phase measurement

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Showing 5 of 25 publications

Conference Committee Involvement (5)

Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XII

10 February 2015 | San Francisco, California, United States

Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XI

4 February 2014 | San Francisco, California, United States

Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications X

6 February 2013 | San Francisco, California, United States

Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications IX

25 January 2012 | San Francisco, California, United States

Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications VIII

26 January 2011 | San Francisco, California, United States

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