Ultra-sensitive and selective gas sensing plays a role in defense and environmental mentoring. Current highly sensitive techniques such as graphene lack selectivity and highly selective techniques such as microresonator soliton dual comb spectroscopy techniques lack the sensitivity of the techniques such as graphene. We have previously developed an ultra-sensitive biosensor known as FLOWER that enables the detection of single macromolecules. FLOWER is based on optical microresonator technology. Here, we adapt FLOWER for highly sensitive and selective chemical sensing by combining it with custom synthesized sorbent polymer coatings. We demonstrate part-per-trillion selective detection of DIMP as well as formaldehyde and ammonia.

Microtoroid resonators are one of the most sensitive chemical sensing technologies. However, coupling light into microtoroids typically requires equipment such as vibration-isolation tables and piezoelectric nanopositioning stages. Translating microtoroids to platforms with small size, weight, power, and cost for chemical vapor sensing remains a challenge. We demonstrate an approach to position photonic nanostructures on the surface of microtoroids to facilitate free-space coupling via inexpensive optics. We have designed the nanophotonic coupler using finite element simulations with novel boundary conditions to accommodate a large simulation domain. The nanophotonic coupler is assembled using a custom manufacturing platform based on automated optical tweezers.

Chip Scale Mass Spectrometry has enabled traditional 1-amu resolution mass spectrometry performance in a compact, ruggedized, and high endurance sensor system called “ACHILLES”. ACHILLES is a fieldable vapor analysis system (10 liter; 13.2 lbs.; 60 W) achieved by integration of three novel subsystems; namely air-sampler/preconcentration, separation and detection stages [Precon/TD-GC-MS] to deliver benchtop gas chromatograph mass spectrometer-quality chemical analysis in a small, ruggedized shoebox formfactor. ACHILLES has been validated in electron impact ionization mode for detection of a broad range of organic chemical threats prioritized by the US DoD and intelligence community and has been independently verified in government tests.

We report results from thin films of novel biomaterials based on natural minerals, never before synthesized in the laboratory using primarily non-toxic and environmentally friendly materials and characterized optically. These biomaterial films have high indices of refraction and would be a natural and toxicologically safe material to use for large-area optical sensing of molecules, including toxic industrial molecules. Adhering modest concentrations of molecules in solution (water/humidity, ethanol, glucose, ammonia, etc.) to the surface of a Fabry-Perot cavity is shown experimentally to sufficiently alter the index of refraction and thickness of the Fabry-Perot films to enable detection of the molecules via optical methods (reflectance, ellipsometry, transmission, etc.). We report laboratory sensing of 3 types of molecules in solution with controlled high-quality Fabry-Perot cavities. We discuss different and better biominerals to use and discern potential applications.

This conference presentation was prepared for the Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXIV conference at SPIE Defense + Commercial Sensing 2023

Rapid, cost-effective, sensitive, and point-of-care disease sensors have become highly sought since the COVID-19 pandemic. We present an approach that achieves the sensitivity of nucleic acid amplification tests in less time. It combines an agglutination assay, lensfree microscopy, and machine learning. Antibody-coated beads sandwich virus particles and agglutinate depending on the viral concentration. By identifying particularly low levels of agglutination, we achieve a 1270 copies/mL limit of detection, comparable to polymerase chain reaction tests. Readout is performed in a cost-effective and compact device. This approach can be sped up further and used to identify other diseases in the future.

Real-time collection and detection are crucial to mitigate airborne biothreats as evidenced during the COVID-19 pandemic. Herein, we numerically and experimentally demonstrate the collection and enrichment of aerosolized polystyrene microparticles using stratified air-water flow in U-shaped and spiral microchannels. Collection efficiencies calculated from multiphase flow simulations show good agreement with the experiment data. The U-shaped channel demonstrates poor particle capture efficiency for submicron particles. To aid this, a two-stage spiral microchannel is designed and fabricated, which shows a 60% higher average particle capture efficiency for submicron particles. Thus, the microchannels enable enrichment and capture of microparticles in sensing-ready solutions.

In this study, our aim is to introduce a novel technique that allows for direct collection of airborne biological particles on SERS substrates and in situ SERS analysis by modifying an inertial impactor, a conventional air sampler based on inertial force. This technique not only enables real-time detection of airborne biological particles without the need for sample preprocessing but also provides identification capability. As a result, it could serve as a simple, portable detection system for monitoring airborne biological particles and is expected to be useful in various atmospheric environment monitoring fields.

The NV-Biosensor uses a fluorescent nitrogen-vacancy center nanodiamond and diamond magnetometry to detect biological targets with high sensitivity. It can be designed to sense nucleic acid or protein biomarkers that are indicative of physiologic conditions, such as viral infection, chem-bio exposure, stress levels, cardiac distress, and even cancer markers. Once fully developed, the NV-Biosensor can be used to continuously monitor Warfighters for their well-being while in the field. We describe our preliminary results to create an NV-Biosensor that can detect nucleic acid biomarkers of stress and include a description of our optical set-up, biochemical methods, bioconjugation strategies and preliminary results.