News Column

Patent Application Titled "Dual Source Analyzer with Single Detector" Published Online

February 10, 2014



By a News Reporter-Staff News Editor at Biotech Business Week -- According to news reporting originating from Washington, D.C., by NewsRx journalists, a patent application by the inventor Sackett, Donald W. (Bedford, MA), filed on August 22, 2012, was made available online on January 30, 2014 (see also Biotechnology Companies).

No assignee for this patent application has been made.

Reporters obtained the following quote from the background information supplied by the inventors: "Spectroscopic instruments are fairly well known. X-ray based instruments, for example, can be used to determine the elemental make up of a sample using x-ray florescence spectroscopy. Portable XRF has become a preferred technique for elemental analysis in the field. Portable XRF is fast, non-destructive, and provides reasonably accurate results (i.e., quantification of elemental concentrations in a wide variety of samples). With XRF, an x-ray tube is used to direct x-rays at a sample. Atoms in the sample absorb x-rays and re-emit x-rays that are unique to the atomic structure of a given element. A detector measures the energy of each x-ray and counts the total number of x-rays produced at a given energy. From this information, the types of elements and the concentration of each element can be deduced. Commercially available analyzers include the Delta manufactured by Olympus NDT and the Niton XLT-3 manufactured by Thermo Fisher Scientific.

"X-rays, however, pose a safety concern. Also, portable and benchtop XRF analyzers have not to date measured beryllium (Be), boron (B), carbon (C), lithium (Li), oxygen (O), nitrogen (N), and the like.

"Laser induced break down spectroscopy (LIBS) devices are known and used to detect the elemental concentration of lower atomic numbered elements with some accuracy. These devices typically include a high powered laser that sufficiently heats a portion of the sample to produce a plasma. As the plasma cools, eventually the electrons return to their ground states. In the process, photons are emitted at wavelengths unique to the specific elements comprising the sample. The photon detection and subsequent measurement of elemental concentrations are very similar to spark optical emission spectroscopy (OES). Examples of LIBS devices are the LIBS SCAN 25 from Applied Photonics, the LIBS25000 from Ocean Optics, and the RT 100 from Applied Spectra.

"Still other instruments are better at determining the molecular compositions present in a sample. Portable, laser based Raman spectrometers or a wide bandwidth based (i.e., non-laser) near infra-red (NIR) analyzers can be used. These devices are configured to collect either Raman spectra or infra-red absorption from a given sample. They then compare the acquired spectra to a library of spectra of pure compounds. From the comparisons, the devices then determine the major compounds present in the sample. The process of determining what combination of pure compounds spectra in published libraries yield the measured spectrum of an unknown mixture is called chemometrics. There are several commercially available portable devices utilizing Raman technology including those manufactured by Thermo Fisher Scientific, Delta Nu and B&W Tek. For NIR, commercially available devices are made by ASD, Thetino Fisher Scientific, and Spectral Evolution.

"Portable Raman and NIR analyzers are able to identify compounds present in a mixture, but they are generally limited to identifying what main compounds are present (as opposed to how much of each compound is present), or, at best, they can provide an approximate quantification of only a few components in a mixture of compounds. This limitation is due to sample response variation as a function of particle size, particle density, and mixture type, whether it be a solid solution or an inhomogeneous mixture of compounds. These parameters can cause the spectrum from one material to be enhanced or reduced relative to the other materials to a fair extent. In addition, both the Raman and NIR methods are sensitive to material very near the sample surface so that any variation is bulk vs. surface concentrations will be missed. Even without these effects, the ability to derive chemical constituents from mathematically combining spectra of pure compounds to simulate the unknown mixture spectrum rapidly degrades after the third compound, even with good quality spectra. In addition, currently available portable Raman and NIR units typically require a good deal of spectral interpretation from the operator, thus limiting user community to more technical users.

"It is also known to fuse the data in dual source systems. That is, for example, Raman spectra data and LIBS spectra data are obtained and software is configured to calculate probability values to pinpoint an unknown material like a microorganism. See for example, published U.S. Patent Application Nos. 2009/0163369 and 2011/0080577 and U.S. Pat. No. 7,999,928 all incorporated herein by this reference. Some of these designs are expensive and complex (using, for example, a FAST spectrometer and fiber optic bundles.)

"Still, LIBS spectroscopy, for example, can produce inaccurate elemental concentrations in some cases and Raman and NIR spectroscopy can report one or more inaccurate compositions, mainly because for many compounds, the Raman or NIR spectra produced by those compounds are very similar. Plus, some libraries contain more than 10,000 spectra from the many compounds. Fusing the data may not improve accuracy."

In addition to obtaining background information on this patent application, NewsRx editors also obtained the inventor's summary information for this patent application: "Featured is a novel portable (e.g., handheld, or easily transportable benchtop or shoulder pack style) instrument that combines measurement from two technologies (e.g., LIBS and Raman or LIBS and NIR) with an analysis algorithm that allows operators to quantify both elements and compounds. Knowledge about the compounds present in the sample enables the method to better report the elemental concentrations. Knowledge about the elemental concentrations enables the method to better quantify the compounds present.

"In addition, the use of the LIBS measurement for elemental concentrations allows a more refined searching of large libraries of pure compound spectra used for NIR and Raman analysis. Therefore, the chemometrics process is also improved via a novel method since the elements present are measured in the sample from LIBS and only compounds comprised of those measured elements can be present in the sample. The knowledge of elemental concentrations thus greatly reduces and refines the library searches for Raman or NIR analysis.

"Another unique feature of the method is that the analytical results are internally consistent and satisfy expected mass balances and constraint equations. This means the total concentration of a given element measured from LIBS will agree with the stoichiometric and molecular composition results from all the compounds that contain that element as determined by the Raman or NIR analysis.

"Also, if trace compounds present in the sample are not detected in the Raman or NIR analysis, then detection of an element using LIBS and knowledge of other compounds actually detected by the Raman or NIR analysis allows the reporting of the trace compounds.

"Featured is a dual source system comprising a high power (e.g., LIBS) laser used to determine elements in a sample and a lower power device (e.g., Raman laser) used to determine compounds present in the sample. An optical subsystem is preferably configured to direct photons from the sample to a detector subsystem after laser energy from the high powered laser strikes the sample along an optical path and to direct photons from the sample to the detector subsystem after energy from the lower powered device strikes the sample along the same optical path.

"The detector subsystem may be configured to receive photons via the optical subsystem from the sample after laser energy from the high power laser strikes the sample and provides a first signal. The detector subsystem also receives photons, via the optical subsystem, after energy from the lower powered device strikes the sample and provides a second signal.

"A controller subsystem is preferably configured to pulse the high power laser and process the first signal to determine one or more elementals present in the sample and to energize the lower power device and process the second signal to determine one or more compounds present in the signal.

"The optical subsystem may further be configured to direct electromagnetic energy from the lower power device to the sample along an optical path including at least a portion of the optical path from the sample to the detector subsystem. The optical subsystem can also be designed to direct electromagnetic energy from the high power laser to the sample along an optical path including at least a portion of the optical path from the sample to the detector subsystem.

"In one example, the lower power device outputs energy at a predetermined wavelength and the optical subsystem includes an optical component receiving energy output by the lower power device and configured to direct said energy to the sample. The optical component may receive photons from the sample and can be configured to filter wavelengths in a narrow band about a predetermined wavelength and to direct energy in wide bands above and below the narrow band to the detection subsystem. In one embodiment, the optical component includes a dichroic notch reflector configured to reflect energy from the lower power device to the sample and to transmit energy in wide bands to the detector subsystem. Or, the reflector can be configured to transmit energy from the lower power device to the sample and to reflect energy in the wide bands to the detector subsystem. One optical subsystem further includes a lens positioned such that photons from the sample after energy from the lower power energy device strikes the sample are received at and focused by the lens. Photons from the sample after energy from the high power device strike the sample are also received and focused by the same lens. The focusing lens can also be positioned to focus energy from the lower power device onto the sample.

"In some examples, the controller subsystem is configured to determine one or more elemental concentrations in the sample based on the first signal and to quantify one or more compounds present in the sample based the one or more elemental concentrations determined to be present in the sample.

"The controller subsystem can be further configured to adjust the measured elemental concentrations based on the determined compounds. In one example, determining one or more elemental concentrations includes using one or more calibration constants and adjusting the elemental concentrations includes using different calibration constants based on the compounds present in the sample. Quantifying a compound in the sample can include using a concentration of an element unique to a compound in order to determine the concentration of the compound. The controller subsystem can be further configured to compare the determined elemental concentrations with elemental concentrations of the defined compound concentrations using mass/balance equations. The controller subsystem can also be configured to quantify concentrations using elements shared among two or more compounds. Also, or in addition, the controller subsystem can be configured to report one or more additional compounds present in the sample based on the elemental concentrations and the one or more determined compounds.

"In some examples, the high power laser source is configured for LIBS spectroscopy and the lower power device is a laser configured for Raman spectroscopy. In other examples, the lower power device is a near infrared source for near infra-red absorption measurements.

"Also featured is a dual source system comprising a high power laser used to determine elements present in a sample, a lower power device used to determine compounds present in a sample, a detector subsystem configured to receive photons from the sample, and an optical path from the sample to the detector subsystem for the elemental determination the same as the optical path for the compound determination. In some examples, an optical path from the lower power device to the sample includes at least a portion of the optical path from the sample to the detector subsystem and/or an optical path from the high power laser to the sample includes at least a portion of the optical path from the sample to the detector subsystem.

"One dual source system includes a high power laser used to determine elements present in a sample, a lower power device used to determine compounds present in a sample, a detector subsystem configured to receive photons from the sample, and a first optical path from the high power laser to the sample at least partially co-linear with a second optical path from the lower power device to the sample. In some examples, an optical path from the sample to the detector subsystem is at least partially co-linear with the first and second optical paths.

"Also featured is a method comprising directing photons from a sample, after impingement of high and low power energy at the sample, via the same optical path from the sample to a detector subsystem and directing lower power energy to the sample via an optical path including at least a portion of the optical path from the sample to the detector subsystem. The method may further include directing higher power energy to the sample via an optical path including at least a portion of the optical path from the sample to the detector subsystem.

"Also featured is a method comprising directing lower power energy to a sample via an optical path, directing high power energy to the sample via an optical path at least partially co-linear with the optical path for the lower power energy, and directing photons from the sample after impingement of high and low power energy at the sample to a detector subsystem. The method may further include directing photons from the sample after impingement of high and low power energy at the sample via the same optical path from the sample to the detector subsystem.

"The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

"Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:

"FIG. 1 shows a schematic three dimensional view showing an example of a portable handheld instrument in accordance with the invention;

"FIG. 2A is a schematic block diagram showing the primary components associated with the portable instrument of FIG. 1;

"FIG. 2B is a block diagram of another example of the invention;

"FIG. 2C is a block diagram of another example;

"FIG. 2D is a block diagram depicting additional examples;

"FIG. 3 is a flow chart depicting the primary steps associated with a method in accordance with the invention and also associated with the programming of the microcontroller subsystem of FIG. 2; and

"FIG. 4 is a schematic view showing a calibration method in accordance with examples of the invention."

For more information, see this patent application: Sackett, Donald W. Dual Source Analyzer with Single Detector. Filed August 22, 2012 and posted January 30, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3745&p=75&f=G&l=50&d=PG01&S1=20140123.PD.&OS=PD/20140123&RS=PD/20140123

Keywords for this news article include: Electronics, Electromagnet, Biotechnology Companies.

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Source: Biotech Business Week


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