of tissues, it can capture 2.5-dimensional topographical information.

There is no substitute for tissue sampling (biopsies) followed by histopathology. The light microscopy methods used to examine these biopsies have not changed significantly in over a century. MUSE can replicate, and in some cases improve upon, conventional transmission light microscopy, but its ability to eliminate the need for histological slide- preparation is likely to be of greater significance. MUSE has the potential to fundamentally change how diagnostic microscopy is practiced.

Gradient Light Interference Microscopy (GLIM) University of Illinois at Urbana-Champaign Developer: Gabriel Popescu

Gradient light interference microscopy (GLIM) exploits a special case of low-coherence interferometry to extract phase information from the specimen, which in turn can be used to measure cell mass, volume, surface area, and their evolutions in time. Because it combines multiple images that correspond

to controlled phase shifts between two interfering waves, gradient light interference microscopy is capable of suppressing the incoherent background due to multiple scattering.

The GLIM module is designed as an add-on connected to the output port of an inverted light microscope. A Wolllaston prism generates two replicas of the image field. The module shifts the phase of one component four times using a spatial light modulator (SLM) while keeping the other component unmodified. Interference patterns generated by these two components are recorded and transferred to a computer for phase-gradient extraction. Four frames are acquired by the GLIM module, one for each phase shift applied by the SLM. Using these images, a phase-gradient map is obtained, which then is integrated along the direction of the shift to recover a quantitative phase map.

GLIM provides a label-free and quantitative method to map the refractive index of live biological cells and tissues. Compared to other methods, GLIM uses a low-coherence white-light source instead of a laser, producing a speckle- free background, and works at a much lower irradiance, reducing light-induced damage to live cells. The method also can render cells in 3D. Furthermore, this method can be overlaid with other imaging modalities, such as fluorescence or bright-field microscopy.

In an early application, GLIM has been used to measure the growth of embryonic bodies in 3D without adding any fl uorescent dyes or tags to the cells. GLIM can show a clear


high-resolution reconstruction of embryonic bodies by using the phase delay as the (intrinsic) contrast agent, without damaging or disturbing the sample. Moreover, due to its imaging speed, the method can study both fast 3D dynamics, such as transport and diff usion in cells, and also slow 3D dynamics, such as cell growth or migration. GLIM can potentially become a valuable tool for in vitro fertilization, where contrast agents and fl uoro- phores may impact the viability of the embryo.

Mochii S Voxa

Developer: Christopher Own

T e Mochii S is a miniature portable scanning electron microscope (SEM) with an integrated energy- dispersive X-ray spectrometer (EDS); it is the size of a coff ee maker and

weighs about 6 pounds. T e wireless user interface allows Mochii S to be remotely operated from across the room or from distant locations. An Apple iPad is employed to control the instrument, process data, and send results by email. Connecting via the cellular network, the internet, or satellite uplink, several users can translate the sample and capture images and EDS spectra. In the future, researchers traveling to Antarctica or the Sahara to search for meteorites, for example, could bring Mochii S along to image and analyze samples immediately upon discovery. Aſt er sample loading, such deep-fi eld researchers could turn over operating control to colleagues elsewhere in the world to continue analysis from thousands of miles away.

When the Mochii S electron source needs replacement, the user replaces the entire electron column in a single quick-change operation. Its 10 kV accelerating voltage and array detector for backscattered electrons provide useful imaging up to 5,000. T is SEM runs on 110/240 VAC, consumes under 85 W, and pumps down in as little as 3 minutes. T e automated 2-axis specimen stage can handle specimens up to 20 mm  20 mm  15 mm. T e Mochii S is low in cost; and, an optional integrated metal coater further reduces costs by eliminating the need for a typical stand- alone EM accessory.

Mochii S is scheduled to launch to the International Space Station in 2019 as a microgravity research platform. However, NASA found that SEM/EDS analysis on the ground has been critical in understanding equipment failures aboard ISS, and the use of Mochii S onboard ISS would reduce decision-making time and increase ISS efficiency. For example, in 2013 a crew member detected a water leak in his helmet during an extravehicular activity (EVA). NASA suspended all EVAs until, more than 6 months later, ground-based SEM/EDS analysis found the cause of the leak to be aluminum silicate debris in the helmet’s fan pump separator. With Mochii S onboard ISS, such analyses could be done as soon as a failure is detected, enhancing crew and vehicle safety. • 2018 September

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