JEOL’s series of low-vacuum scanning electron microscopes get equal doses of technological and stylistic improvements to appeal to a changing customer base.
The electron microscopy market is dominated by the scanning electron microscope (SEM), which is widely used in both materials and biological analysis as one of the few ways to reliably image spatial features in the nanoscale realm. As the user base for SEMs expands, even specialized varieties of electron microscopes are undergoing substantial technical transformations.
Low-vacuum scanning electron microscopes (LV-SEM) are a good example of this “democratization”. Unlike conventional high-vacuum SEMs, LV instruments can handle wet, oily or non-conductive samples without sample preparation. In low-vacuum mode, pressure can be adjusted in the sample chamber to remove the deleterious effect of electrons that build up as charge as the electron beam is rastered on the sample.
In a conventional SEM, the sample would require treatment to make it conductive so as to remove these electrons. These built-up electrons move unpredictably, causing imaging artifacts in the form of lines or streaks. But for many types of analysis applications, particularly in biology, safety and forensics, altering the sample isn’t possible.
The usefulness of LV-SEM has prompted a major revision of JEOL’s line of tungsten/lanthanum hexaboride (LaB6) LV-SEMs, which now features the new, and much different, JSM-IT300LV.
New users, new look
In 2011, JEOL and Nikon launched the NeoScope JCM-6000, a bioscience and industrial benchtop SEM that complemented both optical microscopy and traditional SEMs with its 5- to 15-kV range, SE and BSE imaging and low-vacuum capability. One of the marquee characteristics of this instrument, in addition to small size and low cost, was its unique, stylish appearance that evoked the sort of minimalist design sensibilities of Apple or IKEA.
The firm responsible for the NeoScope’s look is led by Kiyoyuki “Ken” Okuyama, a high-profile designer of industrial products, most famously Italian sports cars such as Ferrari and Maserati. Okuyama’s KO Design was enlisted again to create the look for the IT300LV. Instead of the compact white “box” of the NeoScope, the predominant hue of the new LV-SEM is black, and in multiple finishes. Materials used include a black metallic chromite and black smoked Lexan, a first for a scientific instrument of this kind.
“JEOL’s instruments have always looked a bit utilitarian. This is a radical break of that mindset,” says Vern Robertson, SEM technical sales manager at JEOL, Peabody, Mass. The reason for a specialized—and high-end—design is two-fold, he says. First, JEOL’s developers wanted the instrument to be appealing to users, some of whom might be using an electron microscope for the first time, or who might be only casually using it as part of a large research group. The attractive look helps put users at ease, and provokes interest and curiosity.
Robertson says the whole design paid attention to this effect: “When we do demonstrations of this SEM to prospective customers, I would say more than 80% of customers look around the instrument, even behind it. When they see there’s only one Ethernet cable between the computer and microscope, they see that, yes, they can install it easily. It’s less imposing; there’s less things they have to do.”
The second reason is the impression on non-users.
“For a small to mid-size company buying its first SEM, it’s a big capital investment. They want to show it off to clients and upper management. They are doing failure analysis, or R&D work, and they want to show their clients they are using the latest, greatest technology,” says Robertson.
In addition to the high-end design, the visual appeal is aided by an improved iteration of the graphic user interface that helped JEOL’s 6010 InTouchScope win an R&D 100 Award in 2012. This analytical SEM was the first to offer the capability of touchscreen control directly at the instrument. The traditional interfacing options, including manual controls and Web-based remote control, were all retained. The touchscreen acted much like a tablet computer and was a positively received control improvement.
The 6010 InTouchScope’s touchscreen interface, incorporating pinch, rotate and swipe functions was improved for the IT300LV and updated to feature metallic, 3-D icons and a customizable layout that complement the external design.
Performance under the skin
Why does a workhorse LV-SEM get such a design treatment? Robertson says that users of LV-SEMs are often interdisciplinary groups, or the purchasing decisions are made by committees that include physicists, materials experts and biologists.
“Long gone are facilities where individual scientists have their own SEMs. Increasingly these are ‘tools’ for more casual users, but not limiting the functionality to very high-end users is required,” says Robertson. Today’s instruments have enough hardware and software safety precautions that both the instrument and the sample are well protected.
With the JSM-6610, JEOL’s small and medium-sized customers found, many for the first time, that they could afford to have an in-house SEM with EDS capability. The IT300LV represents the next level up, improving resolution performance to 3 nm at 30 kV and a magnification range of 5 to 300,000X. Like the previous 6610 Series, the vacuum chamber is large to accommodate a wide variety of large and heavy samples.
But elsewhere the new LV-SEM differs from the 6610 Series more dramatically. A major design change was precipitated by the increasing utility of spectroscopy, particularly EDS x-ray microanalysis. These instruments provide chemical information about the sample, which can be constructively paired with the structural resolving power of the electron beam.
“For years, people have done EDS analyses in conjunction with SEM. Typically, they would attach one spectrometer, and that spectrometer was quite small,” says Robertson. “They would struggle to get x-ray counts.”
Two things have changed in recent years, however. One, users have added multiple types of imaging detectors and spectroscopy on the tungsten microscopes. Two, the EDS manufacturers started making larger, higher sensitivity detectors, increasing from 10 mm2 for EDS to greater than 100 mm2 today.
“The acquisition rate is either 10-fold faster for the same amount of data, or 10 times the data for the same acquisition time, improving both data quality and throughput,” says Robertson.
One solution is to increase the number of attachment points for imaging and spectrometry, which JEOL has done for the IT300LV. The instrument has multiple ports for EDS, electron backscatter diffraction, cathodoluminescence detectors, wavelength dispersive x-ray spectrometers, chamberscopes or heating/cooling substages.
But this wasn’t the only change during the redesign of the chamber. A major limitation of x-ray spectroscopy is its line-of-sight; because x-rays don’t have a mass or charge, they can’t usefully resolve highly textured surfaces and produce significant shadowing. In recognition of this effect, JEOL’s engineers revised the chamber design so EDS detectors could be placed 180 degrees apart from each other. This has the effect, says Robertson, “of removing the topography on less than ‘ideal’ samples, which comprise most of the real-world samples.” Another change for the IT300LV, and one that may appeal most to the traditional microscopist, is the 650-Pa pressure range, which is more than twice that of preceding models.
According to Robertson, the audience for this type of low-pressure microscope is niche relative to general analytical SEMs; but the level of interest in analyzing wet samples, oily samples and samples of unusual size or shape, will continue to grow. Strong growth in areas such as food and plant analysis, petroleum or biofuels studies and biofilms has prompted JEOL to make an effort to improve the pressure range.
The design change allowing increased pressure has been to reroute the pumping mechanism through electron optics infrastructure. This allows extra pumping to prevent gas from migrating up the column where the gun is located.
“This helps elevate the pressure, and it’s the first design we’ve done in that regime,” says Robertson. Other vendors have adopted a similar design for certain instruments, and this is still typically focused on a small, niche market.
Studies that can benefit from this type of pumping approach include soft samples. One recent example, says Robertson, is an energy systems company that wanted to examine a boiler tube and determine whether insects were contributing to corrosion. Another example where this is useful is in the biofuels market where scientists closely examine changes in algae.