A novel form of open environment photoacoustic spectroscopy was presented. The technique was firs... more A novel form of open environment photoacoustic spectroscopy was presented. The technique was first applied toward standoff detection of trace surface residues with concentrations as low as 100 ng/cm2. The maximum standoff distance attained was 50 meters under laboratory conditions. The technique was then utilized in a point sensor geometry at concentrations slightly lower than those achieved in standoff. In the present work, the accomplishments include the usage of mechanical oscillators to detect pulses of light, standoff and point sensor geometries showing a wide range of applications for the technique, detection of trace chemical and biological residues at the 100 ng/cm2 concentrations, standoff distances of up to 50 meters, and the ability to distinguish target molecules on a variety of real surfaces. The main analyte focus was placed on the detection of explosive and nuclear proliferation compounds including cyclotrimethylenetrinitromine (RDX), trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), and tributyl phosphate (TBP). Biological compounds were also presented with the goal to distinguish the difference between benign and malignant cells in a standoff manner.
Standoff detection of trace explosives is gaining attention due to its immediate relevance in cou... more Standoff detection of trace explosives is gaining attention due to its immediate relevance in countering terrorist threats based on explosive devices. However, most currently available standoff techniques rely on expensive, complex, and bulky equipment. We have demonstrated highly selective and sensitive standoff detection of explosive residues on surfaces by using photothermal spectroscopy carried out with bimaterial microcantilever sensors. The demonstrated sensitivity of the technique, 100ng/cm2, is sufficient to detect the explosive contamination generally found on explosive devices. The sensitivity of the technique can be further improved by optimizing the bimaterial cantilever and by using higher intensity infrared sources.
... Thomas Thundat, Charles W. Van Neste, Larry R. Senesac, and Adam R. Krause ... JK: Science 28... more ... Thomas Thundat, Charles W. Van Neste, Larry R. Senesac, and Adam R. Krause ... JK: Science 288, 316 (2000) 7. Berger, R., Delamarche, E., Lang, HP, Gerber, C., Gimzewski, JK, Mayer, E., Guntherdot, HJ: Science 276, 2021 (1997) 8. Boisen, A., Thaysen, J., Jensenius, H ...
Micro- and Nanotechnology Sensors, Systems, and Applications VI, 2014
ABSTRACT Chemical sensors based on micro/nanoelectromechanical systems (M/NEMS) offer many advant... more ABSTRACT Chemical sensors based on micro/nanoelectromechanical systems (M/NEMS) offer many advantages. However, obtaining chemical selectivity in M/NEMS sensors using chemoselective interfaces has been a longstanding challenge. Despite their many advantages, M/NEMS devices relying on chemoselective interfaces do not have sufficient selectivity. Therefore, highly sensitive and selective detection and quantification of chemical molecules using real-time, miniature sensor platforms still remains as a crucial challenge. Incorporating photothermal/photoacoustic spectroscopic techniques with M/NEMS using quantum cascade lasers can provide the chemical selectivity without sacrificing the sensitivity of the miniaturized sensing system. Point sensing is defined as sensing that requires collection and delivery of the target molecules to the sensor for detection and analysis. For example, photothermal cantilever deflection spectroscopy, which combines the high thermomechanical sensitivity of a bimetallic microcantilever with high selectivity of the mid infrared (IR) spectroscopy, is capable of obtaining molecular signatures of extremely small quantities of adsorbed explosive molecules (tens of picogram). On the other hand, standoff sensing is defined as sensing where the sensor and the operator are at distance from the target samples. Therefore, the standoff sensing is a non-contact method of obtaining molecular signatures without sample collection and processing. The distance of detection depends on the power of IR source, the sensitivity of a detector, and the efficiency of the collecting optics. By employing broadly tunable, high power quantum cascade lasers and a boxcar averager, molecular recognition of trace explosive compounds (1 μg/cm2 of RDX) on a stainless steel surface has been achieved at a distance of five meters.
ABSTRACT A method of power transmission is proposed that delivers power through the resonance of ... more ABSTRACT A method of power transmission is proposed that delivers power through the resonance of a helical receiver with its surrounding stray capacitance. The system operates in a quasi-wireless state where power is transferred over a single connection to a surface much larger than the dimensions of the receiver. This ensures high-efficiency energy transfer over large areas without the need of strong coupling electromagnetic fields. Standard power connectors such as tracks, plugs, and cords may be easily replaced with conductive surfaces or objects such as foil sheets, desks, and cabinets. Presently, the method is experimentally demonstrated at the small scale using loads of up to 50 W at an efficiency of 83% with both bare and insulated surfaces. Simple circuit modeling of the system is presented which shows close agreement with experimental results.
A novel form of open environment photoacoustic spectroscopy was presented. The technique was firs... more A novel form of open environment photoacoustic spectroscopy was presented. The technique was first applied toward standoff detection of trace surface residues with concentrations as low as 100 ng/cm2. The maximum standoff distance attained was 50 meters under laboratory conditions. The technique was then utilized in a point sensor geometry at concentrations slightly lower than those achieved in standoff. In the present work, the accomplishments include the usage of mechanical oscillators to detect pulses of light, standoff and point sensor geometries showing a wide range of applications for the technique, detection of trace chemical and biological residues at the 100 ng/cm2 concentrations, standoff distances of up to 50 meters, and the ability to distinguish target molecules on a variety of real surfaces. The main analyte focus was placed on the detection of explosive and nuclear proliferation compounds including cyclotrimethylenetrinitromine (RDX), trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), and tributyl phosphate (TBP). Biological compounds were also presented with the goal to distinguish the difference between benign and malignant cells in a standoff manner.
Standoff detection of trace explosives is gaining attention due to its immediate relevance in cou... more Standoff detection of trace explosives is gaining attention due to its immediate relevance in countering terrorist threats based on explosive devices. However, most currently available standoff techniques rely on expensive, complex, and bulky equipment. We have demonstrated highly selective and sensitive standoff detection of explosive residues on surfaces by using photothermal spectroscopy carried out with bimaterial microcantilever sensors. The demonstrated sensitivity of the technique, 100ng/cm2, is sufficient to detect the explosive contamination generally found on explosive devices. The sensitivity of the technique can be further improved by optimizing the bimaterial cantilever and by using higher intensity infrared sources.
... Thomas Thundat, Charles W. Van Neste, Larry R. Senesac, and Adam R. Krause ... JK: Science 28... more ... Thomas Thundat, Charles W. Van Neste, Larry R. Senesac, and Adam R. Krause ... JK: Science 288, 316 (2000) 7. Berger, R., Delamarche, E., Lang, HP, Gerber, C., Gimzewski, JK, Mayer, E., Guntherdot, HJ: Science 276, 2021 (1997) 8. Boisen, A., Thaysen, J., Jensenius, H ...
Micro- and Nanotechnology Sensors, Systems, and Applications VI, 2014
ABSTRACT Chemical sensors based on micro/nanoelectromechanical systems (M/NEMS) offer many advant... more ABSTRACT Chemical sensors based on micro/nanoelectromechanical systems (M/NEMS) offer many advantages. However, obtaining chemical selectivity in M/NEMS sensors using chemoselective interfaces has been a longstanding challenge. Despite their many advantages, M/NEMS devices relying on chemoselective interfaces do not have sufficient selectivity. Therefore, highly sensitive and selective detection and quantification of chemical molecules using real-time, miniature sensor platforms still remains as a crucial challenge. Incorporating photothermal/photoacoustic spectroscopic techniques with M/NEMS using quantum cascade lasers can provide the chemical selectivity without sacrificing the sensitivity of the miniaturized sensing system. Point sensing is defined as sensing that requires collection and delivery of the target molecules to the sensor for detection and analysis. For example, photothermal cantilever deflection spectroscopy, which combines the high thermomechanical sensitivity of a bimetallic microcantilever with high selectivity of the mid infrared (IR) spectroscopy, is capable of obtaining molecular signatures of extremely small quantities of adsorbed explosive molecules (tens of picogram). On the other hand, standoff sensing is defined as sensing where the sensor and the operator are at distance from the target samples. Therefore, the standoff sensing is a non-contact method of obtaining molecular signatures without sample collection and processing. The distance of detection depends on the power of IR source, the sensitivity of a detector, and the efficiency of the collecting optics. By employing broadly tunable, high power quantum cascade lasers and a boxcar averager, molecular recognition of trace explosive compounds (1 μg/cm2 of RDX) on a stainless steel surface has been achieved at a distance of five meters.
ABSTRACT A method of power transmission is proposed that delivers power through the resonance of ... more ABSTRACT A method of power transmission is proposed that delivers power through the resonance of a helical receiver with its surrounding stray capacitance. The system operates in a quasi-wireless state where power is transferred over a single connection to a surface much larger than the dimensions of the receiver. This ensures high-efficiency energy transfer over large areas without the need of strong coupling electromagnetic fields. Standard power connectors such as tracks, plugs, and cords may be easily replaced with conductive surfaces or objects such as foil sheets, desks, and cabinets. Presently, the method is experimentally demonstrated at the small scale using loads of up to 50 W at an efficiency of 83% with both bare and insulated surfaces. Simple circuit modeling of the system is presented which shows close agreement with experimental results.
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