Focus Sharpens on Miniature Optical Spectrometers at Pittcon®

Optical spectroscopy often seems to be somewhat overlooked at Pittcon®, with much of the attention focusing on hyphenated technologies such as GC/MS or ultrahigh-performance liquid chromatography (UHPLC)-MS/MS. Over recent years, renewed interest in the area has been largely led by those products that could either reduce sample volumes or take the analyzer to the sample. This year, there was also activity in combined imaging and spectroscopy instruments, many of which were covered in Barbara Foster’s review: http://www.americanlaboratory.com/913-Technical-Articles/156565- Integrating-Microscopy-Into-the-Analytical-Scheme-A-Pittcon-2014- Microscopy-Review/.

Miniaturizing the future of spectrometer design

There were several innovations on display that promise to further miniaturize and reduce the cost of future optical spectrometers.

This year’s winner of the Pittcon Editors’ Gold Award was the DLP® NIRscan™ evaluation module from semiconductor expert Texas Instruments (Dallas, TX; www.dlp.com), which is a complete optical unit that contains no mechanical parts. The DLP NIRscan is based upon the company’s DLP4500NIR microelectromechanical system (MEMS) device, which is optimized for use with near-infrared (NIR) light in the 700- to 2500-nm range. The MEMS device contains more than 1 million digitally programmable micromirrors that can be easily controlled to employ adaptive scanning techniques to optimize material analysis.

Around the micromirrors, the company has assembled optical slits, diffraction gratings, detectors, and embedded processors to provide an integrated optical unit without mechanical parts to give spectrometer developers a working central unit, around which they can build their specific NIR spectroscopy instrument.

When paired with a single element detector, the DLP4500NIR can replace expensive linear array detectors to create high-performance yet affordable spectrometer designs. The micromirrors enable spectral resolution and wavelength range refinement, adjustment of integration time, and equalize light throughput such that signal-to-noise ratios greater that 30,000:1 can be achieved.

Si-Ware Systems (SWS) (La Cañada, CA; www.si-ware.com) showcased its 2014 SPIE Prism Award-winning MEMS-based single-chip FTIR spectrometer that can be integrated into a wide variety of systems for applications that require qualitative and/or quantitative material analysis.

The first generation of the spectrometer is delivered as a module that consists of a MEMS-based monolithic Michelson interferometer chip that measures just 1 × 1 cm2, an application-specific IC (ASIC) that provides the electronics interface, a single photodetector, and optical fibers.

The spectrometer module operates in the NIR range, and achieves resolutions greater than 30 cm-1 and a signal-to-noise ratio of greater than 1500:1 for 2-sec integration time. It measures just 8 × 6.5 × 4.5 cm3, weighs less than 150 g, and is powered by a USB interface consuming just 750 mW. Further developments are in progress to operate in other wavelength ranges and to achieve even smaller sizes for the module in upcoming generations.

The FTIR spectrometer is the first product to be developed and released based upon Si-Ware’s SiMOST platform, which enables the miniaturization of optical benches on silicon chips using semiconductor microfabrication techniques. SWS is currently providing evaluation kits for its NIR modules, and targets production next fall.

Taking a different approach to the miniaturization challenge was SpectroClick (Champaign, IL; www.spectroclick.com), which announced technology that could potentially build your cell phone into the heart of a spectrometer, using the camera’s built-in complementary metal–oxide–semiconductor (CMOS) sensor as the detector. The company is currently targeting applications in absorption, reflectance, surface plasmon resonance, and fluorescence. Initially, the instrument uses an external CMOS camera operated from and powered by a USB 2.0 port. The spectrometer requires an external package that combines a light source, collimation optics, sample cell, and dispersion device. A prototype of this package was on display at the SpectroClick booth.

In order to overcome the challenges of stray light, inadequate dynamic range, and poor mechanical stability of the CMOS sensors used in phone cameras, the company has developed a patent-pending grating that creates a “SpectroBurst.” This enables the dynamic range of the system to be the product of the dynamic range of the camera and the wide range of grating and optics throughput. The team is currently tackling wavelength calibration and CMOS sensor characterization challenges and plans to have an alpha testing program in place during summer 2014.

Taking the lab to the sample

During the event, SciAps (Woburn, MA; www.sciaps.com) launched the first high-performance, handheld laser-induced breakdown spectroscopy (LIBS) instrument, the Z. SciAps expects the Z to extend the applications for handheld elemental analyzers, especially for alloy producers, positive material identification (PMI), and nondestructive testing (NDT) companies because it can quickly and accurately analyze light in every element from hydrogen to uranium. This significantly extends the range of measurable elements to low-atomic-number elements that are out of the reach for handheld X-ray fluorescence (XRF) instruments. Of particular note is the Z’s ability to measure C, Al, Si, and Mg with similar performance to mobile optical spectrometers. In addition, the instrument interface is based on Google’s Android platform, which provides a simple user interface and enables easy connectivity, data transfer, and reporting.

BaySpec (San Jose, CA; www.bayspec.com) introduced the OCI family of compact hyperspectral imagers, which enable high-performance hyperspectral imaging despite the lightweight handheld form factor of the new OCI-1000 and OCI-2000 instruments. Up until now, widespread adoption of hyperspectral imaging has been limited by instrument size and cost. However, BaySpec has managed to significantly reduce instrument size and cost by developing an image sensor that integrates spectral capability on the chip itself, removing the need for bulky and complex optics.

The instrument weighs less than 363 g and is ideal for handheld, field-based imaging requiring fast acquisition speeds. The instrument runs on an Android-based user interface called SpecPhone, which enables image collection, analysis, and classification. BaySpec envisages the instrument finding applications in a myriad of circumstances, from use on robots and unmanned aerial vehicle (UAV) drones to production lines and in vivo biomedical imaging.

Handheld Raman

There was a lot of activity in the handheld and portable Raman analyzer space, with application-specific instruments for incoming material identification in laboratories and manufacturing facilities sitting alongside devices designed to help law enforcement officers in the field.

Rigaku (Tokyo, Japan; www.rigaku.com) announced its new Progeny handheld Raman analyzer, designed to streamline material identification workflows. At Progeny’s core is an advanced miniature volume phase grating (VPG)-based 1064-nm optical engine, designed to offer benchtop-quality analytical performance in a rugged, ergonomic, and IP-68 sealed enclosure.

Progeny’s fully customizable workflow software is 21 CFR Part 11 compliant and boasts a smartphone-inspired user interface that enables rapid implementation of material identification methods.

The new Progeny analyzer has been designed for pharmaceutical, chemical manufacturing, and academic markets. The instrument manages the most demanding search and quantification algorithms without requiring remote desktop data analysis.

Enhanced Spectrometry (Mountain View, CA; www.enspectr.com) launched the Enspectr RaPort handheld Raman analyzer, which enables real-time, in-situ substance identification at concentrations as low as 1%. Fitted with a 532-nm laser and weighing less than 2 kg, the system can be operated via Windows or Android devices.

Ocean Optics (Dunedin, FL; www.oceanoptics.com) introduced a ruggedized, miniature handheld Raman spectrometer called the IDRaman mini. Measuring just 9.1 cm × 7.1 cm × 3.8 cm and weighing just 330 g, the spectrometer is housed in an aluminum casing and has been designed for material authentication and identification. Available with a 785-nm excitation laser, the system uses an innovative sampling technique known as raster orbital scanning (ROS) that enables more efficient Raman signal collection with lower background effects. The technique is so efficient that just two AA batteries are needed to power the instrument for more than 11 hr. Measuring most samples in less than 9 sec, the IDRaman provides visual confirmation of results and displays both the sample and library spectra with a confidence factor

Snowy Range Instruments (Laramie, WY; wysri.com) also showcased an instrument that uses ROS technology to reliably identify mixtures and shaped samples. The CBEx 1064 instrument is available in an aluminum housing and features a 1064-nm laser that allows fluorescence rejection. The unit is powered by four field-replaceable AA batteries, which enable an operational run time of 4 hr. It also features a resistive touchscreen that can still be easily used while dressed in the highest level of personal protection equipment, permitting safe analysis of chemical, biological, and explosive substances.

B&W Tek (Newark, DE; www.bwtek.com) launched the TacticID field-ready handheld Raman instrument designed to analyze unknown chemicals that law enforcement officers might encounter on the streets. TacticID comes equipped with a database library of over 5000 chemicals, narcotics, cutting agents, explosives, and the ability to scan directly through translucent bottles and packaging to ensure that nontechnical field personnel can readily interpret the readouts. In addition, the device is Wi-Fi enabled and can be operated remotely, allowing analysis at safe distances or on robotic platforms with report transfers possible using secure network protocols.

Smiths Detection (London, U.K.; http://www.smithsdetection.com/) presented the first FTIR spectrophotometer specifically designed to support narcotics officers. Combining the speed and accuracy of FTIR with a library of 2500 narcotics, precursors, cutting agents, and other chemicals, the Target-ID returns identification results in seconds without damaging or degrading the sample. When used with the OSS Surface Sampler, evidence can be easily saved for future reference. The system has a 4-hr battery life and weighs 2.45 kg.

Back to the bench

Among the benchtop analyzers launched at the show, several were on display at the Shimadzu (Columbia, MD; www.ssi.shimadzu.com) booth. The company displayed a new FTIR spectrophotometer designed to meet the need for increased speed and accuracy in infrared analysis. The IRTracer-100 offers a signal-to-noise ratio of 60,000:1 and resolution of 0.25 cm-1, and enables up to 20 spectra to be collected per second. This allows accurate analysis of reactions occurring within a few seconds, and kinetic studies occurring in less than 1 sec. The IRTracer-100 features a stable, airtight interferometer that incorporates a built-in automatic dehumidifier, protecting the unit against moisture and other environmental influences.

Shimadzu also introduced a new series of energy-dispersive X-ray fluorescence spectrometers that incorporate a new, high-performance semiconductor-based detector. The EDX-7000/8000 spectrometers provide excellent sensitivity, resolution, and throughput. The semiconductor detector ensures a high fluorescent X-ray count per unit time, enabling precise, high-resolution analysis while increasing throughput by as much as a factor of 10 compared to the company’s industry-leading predecessor unit. This speed allows researchers and labs to increase their productivity without sacrificing accuracy. A sample positioning camera, collimators to reduce scattering, and five primary filters are all standard features.

Renishaw (Hoffman Estates, IL; www.renishaw.com) presented an update for its inVia Raman microscopes that enables Raman images to be collected faster than ever before. The StreamLineHR Rapide allows users to quickly generate highly detailed Raman images. With enhanced signal-to-noise ratios, accurate measurements are achieved even where extremely low signal levels are present. Users can export high-definition Raman images to see data in all their detail. Because there is no inherent file size limit, it is also possible to record tens of millions of spectra in a single file. The system will find use in materials mapping and bioimaging applications and is sensitive enough to monitor subtle intracellular changes.

Filmetrics (San Diego, CA; www.filmetrics.com) launched a high-performance NIR spectrometer designed for demanding general-purpose applications. Measuring just 4.9 cm high, 6.5 cm long, and 3.75 cm wide, the S3-NIR-1.7 features a TE-cooled 512-element InGaAs array with 500-μm-tall pixels. The instrument and 40,000-hr internal light source can be powered by a single USB port with the TE cooler operating down to –5 °C.

Conclusion

Optical spectroscopy appears to have undergone a renaissance of sorts, with many new and exciting innovations on display during Pittcon 2014. As with any review, there is a limitation on what can be covered. If a product was not covered, it was not an intentional slight.

Perhaps most notable were the innovations and user interfaces that are enabling spectroscopy to be used in the field by trained spectroscopists and field operatives alike. As more industries start to realize the benefits of portable and handheld spectroscopy, not only will general quality and safety improve, but so too will investment in handheld spectrometers. Having seen the excitement generated by these instruments during Pittcon, I envisage a very bright future for optical spectroscopy. The key issue for developers that are not mainstream instrument suppliers will be understanding customer needs and building relationships with existing players to get their products into this global market.

Matt Wilkinson, Ph.D., MBA, is an Account Director for Pinnacle Marketing Communications, Green Park House, 15 Stratton St., London, W1J 8LQ, U.K.; tel.: +44 (0) 2084 296 548; e-mail: matt.wilkinson@pinnaclemarcom.comwww. Pinnacle-Marketing.com

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