Handheld Raman instrumentation has improved drastically over the past few years and is now being used for more complex compounds. What are some of the major challenges faced as handhelds continue to progress?
The first commercial Raman handhelds were developed and sold as early as 2002. These initial opportunities were fueled from the Homeland Security, Hazmat, and Defense markets for unknown material identification, and to a lesser extent, academic and government labs for niche applications. As the market for these systems expanded, pharmaceutical companies recognized their potential as complimentary identification/validation methods to portable near infrared (NIR) systems e.g., NIR on a cart. The primary challenges that most Raman handheld vendors faced were bringing their firmware and software to the strict compliance standards mandated by 21 CFR part 11, and designing algorithms that were amenable to validation (pass/fail) methods instead of identification methods.
Until recently, most handheld Raman systems have been based on 785-nm optical platforms. 785-nm laser excitation dampens fluorescence found in many compounds compared to visible laser excitation, but they are still hindered when identifying and validating many complex compounds. In order to meet the objective of 100% material identification on the loading dock, short wave infrared (SWIR) Raman handheld systems have risen to meet this challenge. SWIR Raman systems have augmented the identification/validation of the various types of micro-crystalline celluloses, biological compounds, pigments, dyes and steroidal compounds.
Handheld SWIR Raman (ca. 1030 nm/1064 nm) expansion has been boosted by modern class III-IV (eg, InGaAs, InGaAsXX) semiconductor detectors with improved quantum efficiency. Transformation of these detectors has been advanced from increased demand in night vision, LIDAR, hyperspectral imaging, and NIR spectroscopy applications. Central to these modern SWIR Raman detectors are physical and electric properties with high quantum efficiency in the 1000-nm to 1700-nm region, with minimal cooling requirements to achieve a high signal-to-noise ratio. Cooling can improve the signal-to-noise ratio of the measurement, but power-hungry thermal electric cooling mechanisms can drain batteries rapidly, and superfluous fans prohibit the immersion/ dust proof ratings of IP67. At SciAps, we have selected class III-IV sensors that require minimal cooling requirements to minimize power consumption and elimination of external fans while still achieving a high signal-to-noise ratio of the handheld SWIR Raman system.
As Raman handheld systems continue to progress, many new challenges will arise such as identification of substances through thicker packaging or vessels, measuring objects from a distance, detection of low concentration substances in mixtures, and reduction in the retail cost of systems.
Handhelds are now being used in a variety of applications. Do you see pharmaceuticals as the biggest growth area? What does the future hold?
Raw material identification using handheld Raman continues to grow at a steady pace. While many “Big Pharma” companies currently employ 785-nm laser excitation, we feel many organizations will recognize the inadequacies of that method and will expand their capabilities to include handheld SWIR Raman.
Many applications will continue to expand beyond the loading dock. For example, US government agencies such as the CDC and FDA recognize that handheld Raman devices can thwart counterfeit drug trafficking. Another high-growth area resides in the medical device field for diagnosis of diseases.
The Inspector 500 has a 1030-nanometer wavelength laser that is used for specialty pharmaceutical compounds. Can you expand on these capabilities and indicate the unique benefits?
The Inspector 500 using the 1030-nm laser and proprietary detector has 3 main advantages. The first is that it can measure more compounds than 785-nm-based devices. One example is that it can be used to distinguish and validate various types of micro-crystalline cellulose compounds that are used as fillers in the pharmaceutical industry. The 785-nm-based systems fall short in that regard. Secondly, this wavelength allows the system to identify substances through thicker and more opaque containers, and through thicker coatings on tablets. And lastly, this proprietary detector and cooling technology provides a very high signal-to-noise ratio system that can also operate without loud fans. This allows the system to meet IP67 requirements. The system also functions with our “free space” technology that permits various sampling attachments for liquids, solids and imaging applications. The imaging application allows the user to pinpoint the laser on very fine grain boundaries on a sample, or measure micron-sized samples.
Can you highlight the positives that are involved with having a single-handed Raman device?
In the pharmaceutical industry the biggest advantage is having a handheld device that can create validated methods for incoming raw materials. It is essential that the device can be employed by warehouse workers with a simple graphical user interface, and the information can be obtained rapidly and immediately downloaded to their protected information management systems. The savings can be calculated based upon reduction in the time to pass materials through the warehouse or quarantine areas, and reduction in the cost of lab measurements which involves consumables and technician time. We have seen ROI from 3 months to 18 months.