Dr. Ashish Tripathi Profile

Dr. Ashish Tripathi

at DEVCOM Chemical Biological Ctr

SPIE Involvement:

Author

Publications (21)

Proceedings Article | 14 June 2023 Presentation + Paper

Don't sleep on sampling: if you don’t catch it, you can’t see it

Daniel Carmany, Ashish Tripathi, Nicholas Manicke, Erik Emmons, Jason Guicheteau, Elizabeth Dhummakupt

Proceedings Volume 12541, 125410P (2023) https://doi.org/10.1117/12.2663938

KEYWORDS: Raman spectroscopy, Statistical analysis, Ionization, Explosives, Equipment, Portability, Mass spectrometry, Ions, Chemical analysis, Particles

Read Abstract +

Proceedings Article | 14 June 2023 Presentation + Paper

Waveguide-enhanced Raman spectroscopy using visible laser excitation

Nathan Tyndall, E. Emmons, Marcel Pruessner, P. Wilcox, A. Tripathi, J. Guicheteau, Todd Stievater

Proceedings Volume 12541, 1254106 (2023) https://doi.org/10.1117/12.2663993

KEYWORDS: Waveguides, Optical filters, Tunable filters, Photonic integrated circuits, Raman spectroscopy, Spectrometers, Signal attenuation, Visible radiation, Silicon nitride, Fluorescence

Read Abstract +

Proceedings Article | 30 May 2022 Presentation + Paper

Portable chemical fingerprint identification system (PCFIS)

Jason Guicheteau, Ashish Tripathi, Kevin Hung, Erik Roese, Phillip Wilcox, Raphael Moon

Proceedings Volume 12116, 1211605 (2022) https://doi.org/10.1117/12.2621042

KEYWORDS: Raman spectroscopy, Chemical analysis, Particles, Forensic science, System identification, Fingerprint recognition, Statistical analysis, Microscopy, Aluminum, Prototyping

Read Abstract +

Proceedings Article | 30 May 2022 Presentation + Paper

Enabling detection technologies for explosive threats

Kevin Hung, Raphael Moon, Erik Roese, Ashish Tripathi, Erik Emmons, Phillip Wilcox, Neal Kline, Jenna Gadberry, Kelley Evans, Caitlin Sharpes, Michele Maughan, Patricia Buckley, Jason Guicheteau

Proceedings Volume 12116, 1211603 (2022) https://doi.org/10.1117/12.2621048

KEYWORDS: Printing, Inkjet technology, Particles, Explosives, Standards development, Polymers, Raman spectroscopy, Chemical analysis, Potassium, Forensic science

Read Abstract +

Proceedings Article | 30 May 2022 Presentation

Sequential raman chemical imaging scanning electron microscopy of deactivated bacterial spores

Ashish Tripathi, Phillip Wilcox, Angela Zeigler, Michael Kim, Daniel Mcgrady, Erik Emmons, Neal Kline, Waleed Maswadeh, Raphael Moon, Richard Vanderbeek, Kevin Hung, Jason Guicheteau

Proceedings Volume PC12116, PC121160A (2022) https://doi.org/10.1117/12.2621049

KEYWORDS: Raman spectroscopy, Scanning electron microscopy, Imaging spectroscopy, Gamma radiation, Ultraviolet radiation, Statistical analysis, Organisms, Microscopy, Machine learning, Electron microscopy

Read Abstract +

Proceedings Article | 5 March 2022 Presentation + Paper

Waveguide-enhanced Raman spectroscopy for field detection of threat materials

Erik Emmons, Phillip Wilcox, Erik Roese, Ashish Tripathi, Jason Guicheteau, Kevin Hung, Benjamin Miller, Ethan Luta, Matthew Yates, Nathan Tyndall, Todd Stievater

Proceedings Volume 12004, 120040L (2022) https://doi.org/10.1117/12.2610654

KEYWORDS: Raman spectroscopy, Waveguides, Polymers, Spectrometers, Silicon, Sensors, Photonic integrated circuits, Microscopy, Imaging spectroscopy, Polymer multimode waveguides

Read Abstract +

Proceedings Article | 9 October 2018 Presentation + Paper

Development of inkjet-deposited test standards for optical sensors

Raphael Moon, Kevin Hung, Erik Roese, Ashish Tripathi, Erik Emmons, Augustus Fountain, Joy Ginter, Amanda Dubbs, Jason Guicheteau

Proceedings Volume 10796, 107960E (2018) https://doi.org/10.1117/12.2326793

KEYWORDS: Printing, Standards development, Chemical analysis, Potassium, Inkjet technology, Statistical analysis, Particles, Forensic science, Raman spectroscopy, Crystals

Read Abstract +

The US Army Research, Development and Engineering Command – Chem Bio center is leading an inter-agency working group, to expand chemical inkjet printing techniques, and to fabricate surface standards in a controlled, uniform and quantifiable fashion, for the evaluation of stand-off active and passive optical systems. A CommercialOff-the-Shelf (COTS) standard inkjet printer was redesigned to deposit precise amounts of chemicals and explosive material on defense relevant surfaces, allowing for the generation of calibration test standards. RDECOM-CB is currently utilizing the inkjet techniques to support an Army forensics detection program where inkjet samples are used for detection of trace energetic materials and illicit drugs of abuse within residual latent fingerprints, as well as leading a North Atlantic Treaty Organization (NATO) Task Group (TG) to develop and recommend to NATO a reference standard methodology (or methodologies) for fabricating quantifiable surface standards for the evaluation of stand-off active and passive optical systems. QA/QC were performed on printed materials to determine accuracy and precision. Raman imaging and the Image-J software package was used to calculate particle statistics such as size distribution, average particle size, and fill factor. The software algorithm finds individual particles and calculates their area from a brightfield image montage. An approximate diameter of each particle, and the total fractional area of the surface covered are also calculated. For qualitative analysis Raman Chemical Imaging is performed to confirm the chemical make-up of the deposited samples. For the quantitative analysis, printed samples were analyzed by either Ion Chromatography with Conductivity Detection (IC-CD) for potassium chlorate based explosives analysis or LC-MS/MS for RDX analysis. We will present the results of inkjet samples produced for the Army forensics program as well as NATO benchmark exercise that consisted of printing trace amounts of inkjet explosive samples and performing QA/QC procedures to determine accuracy, precision and mass transport efficiency.

Proceedings Article | 8 October 2018 Paper

Chemical fingerprint identification system: beyond concept and towards applications for field expeditionary military forensic analysis

Jason Guicheteau, Ashish Tripathi, McKay Allred, Tattianna Olvera, Erik Emmons, Phillip Wilcox, Kevin Hung, Anthony Koertner, Augustus Fountain

Proceedings Volume 10802, 1080208 (2018) https://doi.org/10.1117/12.2326405

KEYWORDS: Particles, Forensic science, Chemical analysis, Raman spectroscopy, System identification, Fingerprint recognition, Statistical analysis, Imaging systems, Imaging spectroscopy, Analytical research

Read Abstract +

Proceedings Article | 16 May 2018 Presentation + Paper

Advancements in MOF characterization for enhanced MALDI sensing

Rabih Jabbour, Ashish Tripathi, Erik Emmons, Phillip Wilcox, Jason Guicheteau, Gregory Peterson, Jared Decoste

Proceedings Volume 10629, 106290H (2018) https://doi.org/10.1117/12.2303501

KEYWORDS: Micro optical fluidics, Matrices, Ions, Molecules, Metals, Chemical analysis, Biological research, Absorption, Ionization, Spectroscopy

Read Abstract +

Proceedings Article | 5 May 2012 Paper

Biomolecule Raman spectral temporal flux from resting bacillus spores in deionized water matrix

Ashish Tripathi, Rabih Jabbour, Jason Guicheteau, Phillip Wilcox, A. Peter Snyder

Proceedings Volume 8358, 83580D (2012) https://doi.org/10.1117/12.911800

KEYWORDS: Raman spectroscopy, Principal component analysis, Organisms, Imaging spectroscopy, Proteins, Molecules, Bacteria, Visible radiation, Microscopy, Environmental sensing

Read Abstract +

Proceedings Article | 3 May 2012 Paper

Standard method for characterizing SERS substrates

Jason Guicheteau, Mikella Hankus, Steven Christesen, Augustus Fountain, Paul Pellegrino, Erik Emmons, Ashish Tripathi, Phillip Wilcox, Darren Emge

Proceedings Volume 8373, 837320 (2012) https://doi.org/10.1117/12.919102

KEYWORDS: Surface enhanced Raman spectroscopy, Raman spectroscopy, Sensors, Spectroscopy, Manufacturing, Scanning electron microscopy, Analytical research, Chemical analysis, Bioalcohols, Defense and security

Read Abstract +

Proceedings Article | 13 October 2011 Paper

Proximal and point detection of contaminated surfaces using Raman spectroscopy

Jason Guicheteau, Steven Christesen, Ashish Tripathi, Erik Emmons, Phillip Wilcox, Darren Emge, Ian Pardoe, Augustus Fountain

Proceedings Volume 8189, 818902 (2011) https://doi.org/10.1117/12.899243

KEYWORDS: Raman spectroscopy, Explosives, Ultraviolet radiation, Chemical analysis, Sensors, Imaging spectroscopy, Contamination, Standoff detection, Forensic science, Laser development

Read Abstract +

Proceedings Article | 5 May 2010 Paper

Water matrix and age effects on microorganism Raman microspectroscopy

Ashish Tripathi, Rabih Jabbour, Patrick Treado, Matthew Nelson, A. Peter Snyder

Proceedings Volume 7665, 766508 (2010) https://doi.org/10.1117/12.839852

KEYWORDS: Raman spectroscopy, Matrices, Bacteria, Organisms, Microscopes, Imaging spectroscopy, Water, Biological research, Principal component analysis, Microorganisms

Read Abstract +

Proceedings Article | 5 May 2010 Paper

Fate study of water-borne gram positive vegetative bacterial cells with Raman microscopy

Jason Guicheteau, Ashish Tripathi, Jennifer Minter, Phillip Wilcox, Steven Christesen

Proceedings Volume 7665, 766502 (2010) https://doi.org/10.1117/12.851147

KEYWORDS: Raman spectroscopy, Bacteria, Visualization, Microscopy, Aluminum, Luminescence, Biological weapons, Contamination, Microscopes, Consciousness

Read Abstract +

Proceedings Article | 28 April 2010 Paper

Trace explosive detection in fingerprints with Raman chemical imaging

Ashish Tripathi, Erik Emmons, Jason Guicheteau, Steven Christesen, Phillip Wilcox, Darren Emge, Augustus Fountain

Proceedings Volume 7665, 76650N (2010) https://doi.org/10.1117/12.865769

KEYWORDS: Raman spectroscopy, Explosives, Imaging spectroscopy, Particles, Explosives detection, Chemical analysis, Raman scattering, Skin, Luminescence, Image analysis

Read Abstract +

Proceedings Article | 8 May 2009 Paper

Bacterial mixture analysis with Raman chemical imaging microspectroscopy

Ashish Tripathi, Rabih Jabbour, Jason Guicheteau, Steven Christesen, Darren Emge, Janet Jensen, A. Peter Snyder

Proceedings Volume 7304, 730403 (2009) https://doi.org/10.1117/12.806456

KEYWORDS: Raman spectroscopy, Picosecond phenomena, Particles, Imaging spectroscopy, Bacteria, Microscopes, Chemical analysis, Visualization, Luminescence, Biological research

Read Abstract +

Proceedings Article | 17 April 2008 Paper

Classification of select category A and B bacteria by Fourier transform infrared spectroscopy

Alan Samuels, A. Peter Snyder, Diane St. Amant, Darren Emge, Jennifer Minter, Mark Campbell, Ashish Tripathi

Proceedings Volume 6954, 695413 (2008) https://doi.org/10.1117/12.767292

KEYWORDS: Pathogens, Fourier transforms, FT-IR spectroscopy, Bacteria, Infrared spectroscopy, Absorption, Organisms, Optical filters, Spectroscopy, Visualization

Read Abstract +

Proceedings Article | 26 April 2007 Paper

Detection and identification of a water mixture of E. coli cells and B. subtilis spores with Raman chemical imaging microscopy

Ashish Tripathi, Rabih Jabbour, Patrick Treado, Jason Neiss, Matthew Nelson, Janet Jensen, A. Peter Snyder

Proceedings Volume 6554, 65540J (2007) https://doi.org/10.1117/12.707788

KEYWORDS: Raman spectroscopy, Microscopes, Particles, Imaging spectroscopy, Chemical analysis, Principal component analysis, Bacteria, Optical spheres, Visualization, Microscopy

Read Abstract +

Proceedings Article | 26 April 2007 Paper

Biological substance characterization in water matrices with Raman microspectroscopy

Rabih Jabbour, Ashish Tripathi, Patrick Treado, Jason Neiss, Matthew Nelson, Janet Jensen, A. Peter Snyder

Proceedings Volume 6554, 65540I (2007) https://doi.org/10.1117/12.707777

KEYWORDS: Raman spectroscopy, Proteins, Matrices, Bacteria, Organisms, Principal component analysis, Imaging spectroscopy, Microscopes, Mahalanobis distance, Laser damage threshold

Read Abstract +

Proceedings Article | 24 June 2002 Paper

Field detection and identification of a bioaerosol suite by pyrolysis-gas chromatography-ion mobility spectrometry

A. Peter Snyder, Ashish Tripathi, Waleed Maswadeh, Jim Ho, Mel Spence

Proceedings Volume 4722, (2002) https://doi.org/10.1117/12.472255

KEYWORDS: Aerosols, Atmospheric particles, Sensors, Biological research, Ions, Spectroscopy, Proteins, Quartz, Ionization, Liquids

Read Abstract +

Improvements were made to a pyrolysis-gas chromatography-ion mobility spectrometry stand-alone biodetector to provide more pyrolyzate compound information to the IMS detector module. Air carrier gas flowing continuously through the pyrolysis tube, the rate of air flow, and pyrolysis rate were found to improve the relative quality and quantity of pyrolyzate compounds detected by the IMS detector compare to earlier work. These improvements allowed a greater degree of confidence in the correlation of biological aerosols obtain in outdoor testing scenarios to a standard GC-IMS biological aerosol dataset. The airflow improvement allowed more biomarker compounds to be observed in the GC-IMS data domain for aerosols of Gram-negative Erwinia herbicola (EH) and ovalbumin protein as compared to previous studies. Minimal differences were observed for Gram-positive spores of Bacillus subtilis var. globigii (BG) from that of earlier work. Prior outdoor aerosol challenges dealt with the detection of one organism, either EH or BG. Biological aerosols were disseminated in a Western Canadian prairie and the Py-GC-IMS was tested for its ability to detect the biological aerosols. The current series of outdoor trials consisted of three different biological aerosol challenges. Forty-two trials were conducted and a simple area calculation of the GC-IMS data domain biomarker peaks correlated with the correct bioaerosol challenge in 30 trials. In another 7 trials, the status of an aerosol was determined to be biological in origin. Two additional trials had no discernible, unambiguous GC-IMS biological response, because they were black water sprays. Reproducible limits of detection were at a concentration of less than 0.5 bacterial analyte-containing particles per liter of air (ACPLA). In order to realize this low concentration, an aerosol concentrator was used to concentrate 2000 liters of air in 2.2 minutes. Previous outdoor aerosol trials have shown the Py-GC-IMS device to be a credible detector with response to determining the presence of a biological aerosol. The current series of outdoor trials has provided a platform to show that the Py-PC-IMS can provide information more specific than a biological or non-biological analysis to an aerosol when the time of dissemination is unknown to the operator. The Py-GC-IMS is shown to be able to discriminate between aerosols of a Gram-positive spore, a Gram-negative bacterium and a protein.

Proceedings Article | 21 December 1999 Paper

Field detection of bacillus spore aerosols with stand-alone pyrolysis-gas chromatography and ion mobility spectrometry

A. Snyder, Waleed Maswadeh, John Parsons, Ashish Tripathi, Henk Meuzelaar, Jacek Dworzanski, Man-Goo Kim

Proceedings Volume 3853, (1999) https://doi.org/10.1117/12.372846

KEYWORDS: Aerosols, Atmospheric particles, Ions, Quartz, Spectroscopy, Sensors, Biological research, Clouds, Chromatography, Solar concentrators

Read Abstract +

A commercially available, hand-held chemical vapor detector was modified to detect Gram-positive Bacillus subtilis var. globigii spores (BG) in outdoor field scenarios. An Airborne Vapor Monitor (AVM) ion mobility spectrometry (IMS) vapor detector was interfaced to a biological sample processing and transfer introduction system. The biological sample processing was accomplished by quartz tube pyrolysis (Py), and the resultant vapor was transferred by gas chromatography (GC) to the IMS detector. The Py-GC/IMS system can be described as a hyphenated device where two analytical dimensions, in series, allow the separation and isolation of individual components from the pyrolytic decomposition of biological analytes. Gram positive spores such as BG contain 5 - 15% by weight of dipicolinic acid (DPA), and picolinic acid is a pyrolysis product of DPA. Picolinic acid has a high proton affinity, and it is detected in a sensitive fashion by the atmospheric pressure-based IMS device. Picolinic acid occupies a unique region in the GC/IMS data domain with respect to other bacterial pyrolysis products. A 1000 to 1, air-to-air, aerosol concentrator was interfaced to the Py-GC/IMS instrument, and the system was placed in an open-air, Western United States desert environment. The system was tested with BG spore aerosol releases, and the instrument was remotely operated during a trial. A Met-One aerosol particle counter was placed next to the Py-GC/IMS so as to obtain a real-time record of the ambient and bacterial aerosol challenges. The presence/absence of an aerosol event, determined by an aerosol particle counter and a slit sampler-agar plate system, was compared to the presence/absence of a picolinic acid response in a GC/IMS data window at selected times in a trial with respect to a BG challenge. In the 21 BG trials, the Py-GC/IMS instrument experienced two true negatives, no false positives, and the instrument developed a software failure in one trial. The remaining 18 trials were true positive determinations for the presence of BG aerosol, and a limit of detection for the Py-GC/IMS instrument was estimated at approximately 3300 BG spore-containing particles.

Showing 5 of 21 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years