Dr. A. G. Unil Perera

Department of Physics & Astronomy, Georgia State University, Atlanta, GA 30303, USA

Dr. A. G. Unil Perera

Department of Physics & Astronomy, Georgia State University, Atlanta, GA 30303, USA

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Academic Career Length

33Years (1994-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 December 2017 in Scientific Reports

Journal Article

ATR-FTIR spectral discrimination between normal and tumorous mouse models of lymphoma and melanoma from serum samples

Hemendra Ghimire

Mahathi Venkataramani

Zhen Bian

Yuan Liu

A. G. Unil Perera

This study presents, attenuated total reflection Fourier transforms infrared spectroscopy of dried serum samples in an effort to assess biochemical changes induced by non-Hodgkin’s lymphoma and subcutaneous melanoma. An EL4 mouse model of non-Hodgkin lymphoma and a B16 mouse model of subcutaneous melanoma are used to extract a snapshot of tumor-associated alteration in the serum. The study of both cancer-bearing mouse models in wild types and their corresponding control types, emphasizes the diagnostic potential of this approach as a screening technique for non-Hodgkin lymphoma and melanoma skin cancer. Infrared absorbance values of the different spectral bands, hierarchical clustering and integral values of the component bands by curve fitting, show statistically significant differences (student’s t-test, two-tailed unequal variance p-value < 0.05) between spectra representing healthy and tumorous mouse. This technique may thus be useful for having individualized route maps for rapid evaluation of lymphoma and melanoma status and associated therapeutic modalities.

27 June 2020 in Cancers

Journal Article

Protein Conformational Changes in Breast Cancer Sera Using Infrared Spectroscopic Analysis

Hemendra Ghimire

Chakravarthy Garlapati

Protein structural alterations, including misfolding and aggregation, are a hallmark of several diseases, including cancer. However, the possible clinical application of protein conformational analysis using infrared spectroscopy to detect cancer-associated structural changes in proteins has not been established yet. The present study investigates the applicability of Fourier transform infrared spectroscopy in distinguishing the sera of healthy individuals and breast cancer patients. The cancer-associated alterations in the protein structure were analyzed by fitting the amide I (1600–1700 cm⁻¹) band of experimental curves, as well as by comparing the ratio of the absorbance values at the amide II and amide III bands, assigning those as the infrared spectral signatures. The snapshot of the breast cancer-associated alteration in circulating DNA and RNA was also evaluated by extending the spectral fitting protocol to the complex region of carbohydrates and nucleic acids, 1140–1000 cm⁻¹. The sensitivity and specificity of these signatures, representing the ratio of the α-helix and β-pleated sheet in proteins, were both 90%. Likewise, the ratio of amides II and amide III (I₁₅₅₆/I₁₂₉₅) had a sensitivity and specificity of 100% and 80%, respectively. Thus, infrared spectroscopy can serve as a powerful tool to understand the protein structural alterations besides distinguishing breast cancer and healthy serum samples.

28 August 2006 in Applied Physics Letters

Journal Article

Ga N ∕ Al Ga N ultraviolet/infrared dual-band detector

G. Ariyawansa

M. B. M. Rinzan

M. Alevli

M. Strassburg

N. Dietz

H. C. Liu

Group III-V wide band gap materials are widely used in developing solar blind, radiation-hard, high speed optoelectronic devices. A device detecting both ultraviolet (UV) and infrared (IR) simultaneously will be an important tool in fire fighting and for military and other applications. Here a heterojunction UV/IR dual-band detector, where the UV/IR detection is due to interband/intraband transitions in the

{Al}_{0.026} {Ga}_{0.974} N

barrier and GaN emitter, respectively, is reported. The UV threshold observed at

360 nm

corresponds to the band gap of the

{Al}_{0.026} {Ga}_{0.974} N

barrier, and the IR response obtained in the range of

8 - 14 μ m

is in good agreement with the free carrier absorption model.

14 July 2008 in Applied Physics Letters

Journal Article

Uncooled infrared detectors for 3–5μm and beyond

P. V. V. Jayaweera

S. G. Matsik

A. G. Unil Perera

H. C. Liu

M. Buchanan

Z. R. Wasilewski

Avoiding cryogenic cooling not only reduces the cost and weight but also simplifies the infrared detector system allowing widespread usage. Here an uncooled infrared detection using intravalence bands is reported. A set of three

p - Ga As ∕ {Al}_{x} {Ga}_{1 - x} As

multiple heterojunction detector structures were used to demonstrate the concept experimentally. A preliminary detector showed peak responsivity of

0.29 mA ∕ W

2.5 μ m

300 K

. The intravalence band approach can be used to cover various wavelength ranges by using different material systems giving rise to the possibilities of a dual band detector operating in atmospheric windows.

9 February 2005 in Applied Physics Letters

Journal Article

AlGaAs emitter∕GaAs barrier terahertz detector with a 2.3 THz threshold

M. B. M. Rinzan

A. G. Unil Perera

S. G. Matsik

H. C. Liu

Z. R. Wasilewski

M. Buchanan

A heterojunction interfacial work function internal photoemission (HEIWIP) detector with a threshold frequency

(f_{0})

of 2.3 THz

(λ_{0} = 128 μ m)

is demonstrated. The threshold limit of

\sim 3.3 THz

(92 μm) due to the Al fraction being limited to

\sim 0.005

, in order to avoid control and transition from alloy to isoelectronic doping behavior, was surpassed using AlGaAs emitters and GaAs barriers. The peak values of responsivity, quantum efficiency, and the specific detectivity at 9.6 THz and 4.8 K for a bias field of

2.0 kV ∕ cm

are

7.3 A ∕ W

, 29%,

5.3 \times 10^{11}

Jones, respectively. The background-limited infrared photodetector temperature of 20 K with a

60 °

field of view was observed for a bias field of

0.15 kV ∕ cm

. The

f_{0}

could be further reduced toward

\sim 1 THz

regime

(\sim 300 μ m)

by adjusting the Al fraction to offset the effect of residual doping, and/or lowering the residual doping in the barrier, effectively lowering the band bending.

9 December 2013 in Applied Physics Letters

Journal Article

InAs/GaAs p-type quantum dot infrared photodetector with higher efficiency

Yan-Feng Lao

Seyoum Wolde

A. G. Unil Perera

Y. H. Zhang

T. M. Wang

Sanjay Krishna

An InAs/GaAs quantum dot infrared photodetector (QDIP) based on p-type valence-band intersublevel hole transitions as opposed to conventional electron transitions is reported. Two response bands observed at 1.5–3 and 3–10 μm are due to transitions from the heavy-hole to spin-orbit split-off QD level and from the heavy-hole to heavy-hole level, respectively. Without employing optimized structures (e.g., the dark current blocking layer), the demonstrated QDIP displays promising characteristics, including a specific detectivity of

1.8 \times 10^{9}

cm \cdot {Hz}^{1 / 2}

/W and a quantum efficiency of 17%, which is about 5% higher than that of present n-type QDIPs. This study shows the promise of utilizing hole transitions for developing QDIPs.

About Me

A.G. Unil Perera earned his B.S. in Physics with first-class honors from the University of Colombo (UOC), Sri Lanka, and his M.S. and Ph.D. degrees from the University of Pittsburgh, USA. Dr. Perera is a Fellow of the IEEE and a Life Fellow of both SPIE and the American Physical Society. Dr. Perera's research initially focused on developing tunable and bias-selectable detectors with sensitivity spanning from ultraviolet to far-infrared regions. More recently, he has been concentrating on IR applications for the early detection of diseases and monitoring the treatment efficacy of the drugs. His innovative work has resulted in 12 patents, editing 4 books, 12 invited book chapters, and over 225 publications. He has received numerous accolades throughout his career, including being named the Most Outstanding Undergraduate of the Year by the UOC, and winning the Outstanding Junior Faculty Award, the Outstanding Faculty Achievement Award, and the Alumni Distinguished Professor Award from GSU. In 2012, he was honored by the University System of Georgia with the title of "Regents' Professor," the system's highest academic distinction. In addition to his research and teaching. He has contributed significantly to his field through professional service. He served on the editorial board of the IEEE Journal of Electron Device Society, was a Distinguished Lecturer for the IEEE Photonics Society from 2020- 22, and is a member of the Sectional Editorial Board of the Sensors.

Dr. A. G. Unil Perera

Dr. A. G. Unil Perera

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