By Clinton Shaffer
Spectroscopy is a non-contact diagnostic technique that can quickly identify and characterize physical materials by evaluating variations in a material’s absorption or emission of different wavelengths of light. Because it is non-destructive, efficient, and highly accurate, spectroscopy is driving change and spurring innovation in a great many fields. Some current uses of the technology include identifying unknown materials by comparing them to catalogued spectral signatures, detecting the presence of known substances, inspecting the quality of a material, and analyzing the chemical composition of a substance.
While spectroscopy can be performed using visible, infrared (IR), or ultraviolet (UV) light, the near-infrared (NIR) region is particularly rich in molecular vibrational mode information, making it ideal for molecular spectroscopic applications. One emerging application area for NIR spectrometer integration is in the development of handheld instruments. In contrast to stationary, laboratory-bound spectrometers, the newer versions of these imaging devices provide portability, point-and-click functionality, and rapid collection and access to data in the field.
I recently spoke with Mariquita Gordon, business manager of DLP embedded products at Texas Instruments, to discuss the company’s new NIR technologies and talk about the emerging market for portable NIR spectrometers.
According to Gordon, bringing portability to NIR spectroscopy “fundamentally changes how you measure something.”
Thanks to these handheld diagnostic devices, tests that were traditionally done by specialists in some cloistered lab can now be done in the field by anyone. As Gordon put it, “the person holding the instrument doesn’t have to be an expert.”
Portable NIR spectrometers, when used in conjunction with a high speed processer, software that incorporates a database of spectral signatures, and a cloud-based platform, enable innovative and more efficient ways of handling countless applications.
NIR spectroscopy is already a widely adopted technology in the agricultural industry. It is used for many applications, from soil content analysis to QA testing for goods like fruits, vegetables, and grain products. The use of portable NIR spectrometers is making these processes more efficient, enabling employees in the field to take measurements and receive instantaneous results.
As a closely related field to agriculture, the food processing industry can leverage portable NIR spectrometers in a similar fashion. Instead of taking samples to a lab to be tested by materials experts, a worker on the ground floor of a factory can routinely evaluate food products in order to ensure product integrity on a more consistent basis.
NIR spectroscopy is very advantageous for pharmaceutical applications, as regulations demand stringent quality control. As with the other applications, portable NIR spectrometers enhance the efficiency of the testing process by bringing the testing equipment to where the materials are.
Oil and Gas
Oil and gas companies have unique indicating markers in their products that designate ownership. Portable NIR spectrometers enable anyone in the field to simply point, click, and accurately identify the oil marker and the concentration of that marker in a sample, which is highly valuable for critical applications like identifying oil at a spill. It is also beneficial for fracking applications, where groundwater can be analyzed to differentiate between residuals from a fracking pool and naturally occurring hydrocarbon.
Portable NIR spectroscopy also translates directly to security applications. With a handheld spectrometer, security agencies like the U.S. Transportation Security Administration (TSA) can easily evaluate ambiguous contents and immediately identify a potentially harmful substance like a drug or explosive. Reflectance spectroscopy even allows for this type of testing to be done through clear surfaces, like glass or plastic.
Portable NIR devices are also in demand in the medical industry, amidst the ceaseless proliferation of other point-of-care medical devices. From evaluating bodily fluids for sugars or toxins to evaluating moisture levels on the surface of the skin, the ability to perform NIR spectroscopy anywhere is a huge boon for medical facilities.
New Tools For The Design Of Handheld NIR Spectroscopy Devices
OEMs working in these and other application areas now have a pair of new tools at their disposal to facilitate the integration of NIR spectroscopy into their designs. TI recently released a new DLP (Digital Light Processing) chipset and evaluation module geared toward developing portable, handheld NIR spectrometers.
DLP technology is certainly not synonymous with NIR spectroscopy, since it has traditionally been associated with cinema, office, and classroom projection technologies. That, however, has never stopped engineers from dissembling DLP equipment and using the technology in novel designs. For over 15 years, engineers have been using DLP devices, which feature micro-electromechanical system (MEMS) technology, as powerful optical sensors.
In order to help companies meet the demand for portable NIR spectrometers, TI developed a new device and evaluation module specifically for handheld NIR applications. The products were devised to help simplify the design and prototyping processes for engineers and to empower students to experiment and learn about NIR spectroscopy.
The DLP NIR device (DLP4500NIR) is meant to be an effective and less expensive alternative to InGaAs detector arrays. It features high resolution in a small form factor, providing a 912 by 1,140 resolution array in a 9.1 mm by 20.7 mm body size. It is compatible for use with 700 to 2,500 nm light and programmable to select and attenuate multiple wavelengths at speeds of up to 4 kHz.
For those who don’t specialize in optics, TI’s evaluation module (DLP NIRscan) incorporates the DLP4500NIR and provides a “plug-and-play” functionality that facilitates the design process. TI is known for the out-of-the-box usability of its evaluation modules. For example, at Photonics West earlier this year I spoke with students from the University of Puerto Rico at Mayagüez (UPRM) who built a 3D printer from scratch — using an earlier evaluation module called the DLP LightCrafter — in only five months.
Even if you are an optics expert, the DLP NIRscan evaluation module can streamline the design process. In order to develop a prototype, it could take six to nine months to independently integrate and customize the DLP device. With the evaluation module, engineers can spend time customizing the other parameters of their device necessary for the specific application, rather than spending time on the chipset.
New and innovative technologies — like the DLP NIR spectroscopy devices — are bringing portability to NIR spectroscopy and fundamentally changing how substances are measured. One would only need to envision a drone equipped with a payload of this type of sensory equipment to fathom the impact of the technology. Diagnosing substances located anywhere in the world and receiving the results instantaneously is completely plausible – even measurements of the most hazardous materials in the most difficult to reach places.
Perhaps the most exciting thing about these devices, according to Gordon, is “that you can now measure what you couldn’t before.” It opens up worlds of possibilities.
There are countless applications that portable NIR spectrometers can enable. What application(s) are you working on? In what industry do you think portable NIR spectroscopy will have the most impact? Aside from TI’s DLP technology, what other tools are you using to facilitate your NIR spectroscopy designs?
Additional Resources: Texas Instruments DLP Technology For Spectroscopy White Paper