Development of a compact, handheld Raman instrument with no moving parts for use in field analysis

Cullum, Brian M.; Mobley, Joel; Chi, Zhenhuan; Stokes, David L.; Miller, Gregory R.; Vo‐Dinh, Tuan

doi:10.1063/1.1150504

Cited by 45 publications

(33 citation statements)

References 34 publications

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“…Finally, such selection of limited wavelength subsets may provide new impetus to the development of tunable detection filter-based serial Raman acquisition systems. 19,20 These systems greatly alleviate the large spatial footprint drawback of standard Raman systems but suffer from longer acquisition time requirements. By employing only a fraction of the total set of wavelengths, we envision a significant reduction in the acquisition time because of the serial sampling nature of such systems.…”

Section: Introductionmentioning

confidence: 99%

Wavelength selection-based nonlinear calibration for transcutaneous blood glucose sensing using Raman spectroscopy

et al. 2011

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Abstract. While Raman spectroscopy provides a powerful tool for noninvasive and real time diagnostics of biological samples, its translation to the clinical setting has been impeded by the lack of robustness of spectroscopic calibration models and the size and cumbersome nature of conventional laboratory Raman systems. Linear multivariate calibration models employing full spectrum analysis are often misled by spurious correlations, such as system drift and covariations among constituents. In addition, such calibration schemes are prone to overfitting, especially in the presence of external interferences that may create nonlinearities in the spectra-concentration relationship. To address both of these issues we incorporate residue error plot-based wavelength selection and nonlinear support vector regression (SVR). Wavelength selection is used to eliminate uninformative regions of the spectrum, while SVR is used to model the curved effects such as those created by tissue turbidity and temperature fluctuations. Using glucose detection in tissue phantoms as a representative example, we show that even a substantial reduction in the number of wavelengths analyzed using SVR lead to calibration models of equivalent prediction accuracy as linear full spectrum analysis. Further, with clinical datasets obtained from human subject studies, we also demonstrate the prospective applicability of the selected wavelength subsets without sacrificing prediction accuracy, which has extensive implications for calibration maintenance and transfer. Additionally, such wavelength selection could substantially reduce the collection time of serial Raman acquisition systems. Given the reduced footprint of serial Raman systems in relation to conventional dispersive Raman spectrometers, we anticipate that the incorporation of wavelength selection in such hardware designs will enhance the possibility of miniaturized clinical systems for disease diagnosis in the near future. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Section: Introductionmentioning

confidence: 99%

Wavelength selection-based nonlinear calibration for transcutaneous blood glucose sensing using Raman spectroscopy

et al. 2011

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“…Extended X-ray absorption fine structure (EXAFS) was used for the first time to investigate the bonding structures of adsorbed As(V) on the SERS substrate, as well as the mechanism of the Ca 2+ effect on the SERS analysis of As(V). As(V) was found to be adsorbed on Ag nanofilm through formation of bidentate binuclear surface complexes (AgO) 2 AsO 2 À with an average AsÀAg interatomic distance of 2.56 Å in the As(V) single adsorbate system, and through formation of a ternary surface complex (AgO)(CaO) 2 AsO + with an average AsÀAg distance of 3.03 Å in the presence of Ca 2+ . The formation of the ternary surface complex dramatically decreased the SERS sensitivity and resulted in a shift of the SERS As(V) band from 780 cm À1 for the As(V) system to 790 cm À1 in the As(V)ÀCa 2+ binary adsorbate system.…”

Section: Introductionmentioning

confidence: 99%

“…A feasible promising route for field analysis of arsenic is to develop a highly active substrate for surface-enhanced Raman scattering (SERS) of arsenic that can be used in conjunction with portable Raman technology. 2 Recently, Mulvihill et al 3 and our group 4 used Ag nanoparticles for sensitive SERS analysis of arsenic species at the low microgram per liter level in solutions. In our study, Ag nanofilm was prepared on glass slides with a modified mirror reaction, and the SERS analysis was conducted by transferring 10 μL of arsenic solutions onto the nanofilm followed by recording the SERS spectra with a Raman spectrometer.…”

Section: ' Introductionmentioning

confidence: 99%

“…The Ca effect was attributed to the formation of the Ca 3 (AsO 4 ) 2 precipitate. However, thermodynamic calculations based on a K sp = 6.8 Â 10 À19 for Ca 3 -(AsO 4 ) 2 25 predicted that the precipitate should not be formed in the SERS analysis solution containing 5 mg/L As(V) and 10 mg/L Ca 2+ . In addition, the much higher sensitivity and distinct position of the As(V) band at 790 cm À1 in Figure 3A, compared to that of the normal Raman As(V) band, certainly indicated that the 790 cm À1 band was generated by adsorbed As(V) on the Ag nanofilm.…”

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confidence: 99%

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Effect of Bonding Interactions between Arsenate and Silver Nanofilm on Surface-Enhanced Raman Scattering Sensitivity

Jing

Hao

et al. 2011

J. Phys. Chem. C

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Arsenic is one of the most common inorganic contaminants in groundwater worldwide due to natural and anthropogenic sources.1 Although a number of laboratory instruments are used for accurate measurement of arsenic in environmental samples at microgram per liter concentrations, there is still a necessity for development of simple and rapid methods for field assays. A feasible promising route for field analysis of arsenic is to develop a highly active substrate for surface-enhanced Raman scattering (SERS) of arsenic that can be used in conjunction with portable Raman technology. Recently, Mulvihill et al. 3 and our group 4 used Ag nanoparticles for sensitive SERS analysis of arsenic species at the low microgram per liter level in solutions. In our study, Ag nanofilm was prepared on glass slides with a modified mirror reaction, and the SERS analysis was conducted by transferring 10 μL of arsenic solutions onto the nanofilm followed by recording the SERS spectra with a Raman spectrometer. 4 The results suggest that SERS offers great promise for the development of sensitive, rapid, and portable techniques for analysis of arsenate (As(V)) and arsenite (As(III)) species. However, we also observed that Ca 2+ , a common cation in natural waters, significantly reduced the sensitivity of SERS analysis.The extremely high sensitivity of SERS 5,6 is widely attributed to the electromagnetic enhancement (EM) effect and chemical enhancement (CE) or charge transfer effect. 7,8 While the EM effect is primarily caused by the local electric field around the adsorbed molecules, the CE effect requires direct proximity or chemical bonding between the molecules and the surface metal atoms. It has been reported that SERS sensitivities are related to the adsorption affinity and surface orientation of analytes for the metal nanosurface and to the distance between the analytes and the surface. 9À12 However, no bonding structures of analytes on the SERS active surface have been measured directly. The lack of this crucial information prevents accurate theoretical calculations of the CE factors. 13À17Extended X-ray absorption fine structure (EXAFS) is a wellestablished and powerful spectroscopic technique to determine local structural information for adsorbed species on mineral surfaces. 18À20 We have used the technique to determine the bonding structures of adsorbed arsenic species on iron and titanium oxides. 21 In this article, EXAFS was used to directly ABSTRACT: The effect of Ca 2+ on surface-enhanced Raman scattering (SERS) analysis of arsenate (As(V)) using Ag nanofilm was studied. Extended X-ray absorption fine structure (EXAFS) was used for the first time to investigate the bonding structures of adsorbed As(V) on the SERS substrate, as well as the mechanism of the Ca 2+ effect on the SERS analysis of As(V). As(V) was found to be adsorbed on Ag nanofilm through formation of bidentate binuclear surface complexes (AgO) 2 AsO 2 À with an average AsÀAg interatomic distance of 2.56 Å in the As(V) single adsorbate system, and through forma...

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“…For example, to remove the diffraction grating, Lewis et al (13) and several other investigators (14,15) adopted acoustooptic tunable filters (AOTFs). In this solution, an acoustic-optical (AO) device was applied as a tunable-wavelength filter/switch.…”

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confidence: 99%

Lightweight Raman spectroscope using time-correlated photon-counting detection

Meng

Petrov

Cheng

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Raman spectroscopy is an important tool in understanding chemical components of various materials. However, the excessive weight and energy consumption of a conventional CCD-based Raman spectrometer forbids its applications under extreme conditions, including unmanned aircraft vehicles (UAVs) and Mars/Moon rovers. In this article, we present a highly sensitive, shot-noise-limited, and ruggedized Raman signal acquisition using a time-correlated photon-counting system. Compared with conventional Raman spectrometers, over 95% weight, 65% energy consumption, and 70% cost could be removed through this design. This technique allows space-and UAV-based Raman spectrometers to robustly perform hyperspectral Raman acquisitions without excessive energy consumption. Comparing with other molecular-specific imaging techniques, Raman spectroscopy provides a label-free contrast mechanism, which is intrinsically induced by the molecules contained in the sample. Relying on internal properties of molecules, investigators can avoid complicated sample preparation processes and molecular-specific labeling, etc. In many imaging/sensing applications, Raman spectroscopy often provides superior molecular specificity, imaging speed, and spectral resolution, and is usually considered as an emerging imaging technique (8, 9). However, despite decades of intensive study, Raman spectroscopy is still not widely applicable in space-based detection systems including unmanned aircraft vehicles (UAVs) and Mars/Moon rovers. This is mainly due to two hurdles: the unacceptable heavy weight of conventional spectrometers, and the excessive energy consumption by the entire system, especially the CCD camera.In typical laboratory-based Raman spectroscope setups, a beam of light is focused onto the sample. The scattered photons are then collected by a condenser lens and sent into a spectrometer. A diffractive grating is usually used to induce a spatial dispersion of the Raman peaks into different wavelengths. A CCD camera is used as the detector. In this sense, a correspondence between the CCD pixel and Raman shift can be established, and the Raman peaks are recognized and recorded.However, when extending this approach to field circumstances (e.g., space-based vehicles or UAVs), several key limitations emerge. First, due to the tiny angular dispersion provided by diffractive gratings, a long optical propagation length is required to create sufficient spatial dispersion. This is usually not allowed in space-based vehicles. Moreover, this long propagation length, together with any possible moving parts contained in the grating-based spectrometers, is unable to tolerate excessive vibrations during the launching/landing process of a space-based vehicle. Furthermore, the excessive energy consumption for the CCD cameras, especially for the cooling process, is usually not affordable by UAVs or spacebased vehicles/rovers. Finally, the weight of the spectrometer is also a problem (10-12).To overcome these difficulties, investigators invented and used several differe...

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Development of a compact, handheld Raman instrument with no moving parts for use in field analysis

Cited by 45 publications

References 34 publications

Wavelength selection-based nonlinear calibration for transcutaneous blood glucose sensing using Raman spectroscopy

Wavelength selection-based nonlinear calibration for transcutaneous blood glucose sensing using Raman spectroscopy

Effect of Bonding Interactions between Arsenate and Silver Nanofilm on Surface-Enhanced Raman Scattering Sensitivity

Lightweight Raman spectroscope using time-correlated photon-counting detection

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