MicroscopyInnovations
and cellular remodeling processes such as neuronal remodeling before and aſt er synapses.
CryoView MP TM – MultiProbe Low-Temperature SPM
Nanonics Imaging, Ltd. Developer: Aaron Lewis
probe scanning probe microscopy (SPM) platform designed to study mechanical, spectroscopic, optical, thermal, and electrical properties at low temperatures. By employing up to four individual probes that can be
The CryoView MP™ is a multiple-
operated independently and simultaneously, the CryoView MP can perform a variety of characterization and transport measurements in situ in combination with light microscopy techniques such as Raman, fluorescence, and near-field scanning optical microscopy (NSOM) in a controlled environment from room temperature down to 10 K. Advanced forms of SPM are enabled for each individual probe, including AFM, KPM, EFM, S-NSOM, NSOM, STM, AFM-Raman, and TERS.
Previously, Raman and photoluminescence measure- ments would be carried out on one system, with electrical transport done on a separate probe station, and AFM and Kelvin probe measurements performed on a third system. Finding the exact same spot and conditions for each of these measurements is challenging. With CryoView MP the probe and sample are maintained in close contact through tuning-fork-based feedback, a laser-free feedback method providing force sensitivity without optical artifacts. Enclosed in a high-vacuum chamber, the CryoView MP can be pumped down using a rapid cooling mechanism, reaching tempera- tures down to 10 K.
Applications possible over a range of temperatures include the following: (a) electrical probe station combined with in situ
simultaneous Raman characterization, (b) nanoscale transport measurements, where one probe serves as the excitation source and the second probe maps the transport process, (c) chemical lithography with one probe and high-resolution imaging with a second probe, and (d) combined SPM measurements where one probe can perform an advanced SPM measurement while a high-resolution AFM tip maps the same area.
A particular application is the analysis of 2D materials such as graphene, MoS 2 , BN, NBSe 2 , metamaterials, and metasurfaces as well as other functional materials such as Si, carbon nanotubes, III-V semiconductors, and quantum dots. In order to fully examine the potential of these materials, multiple characterization methods need to be brought together to provide a complete understanding of their performance. Some of these methods include: nanometric photoconductivity, nanoelectrical characteristics (electronic
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mobility, charge carriers, etc.), thermal properties, and the quantum Hall eff ect.
Lens-Free Computational Microscopy for Giga-Pixel 3D Imaging
Aydogan Ozcan of the University of California at Los Angeles
Developers: Aydogan Ozcan, Alon Greenbaum, and Yibo Zhang
Light microscopy examination of microscale features in pathology slides is one of the gold standards for diagnosing disease. T e use of conven- tional light microscopes, however, is oſt en limited because of their relatively high cost; the bulkiness of lens-based optics; and such characteristics as small
fi eld of view (FOV), the need for lateral specimen translations, and the need for repeated focus adjustments. T e computa- tional lens-free holographic on-chip microscope can mitigate these challenges. T is device is based on the solution of the transport of intensity equation to generate an initial phase guess to the multi-height iterative phase retrieval algorithm as well as rotational fi eld transformations implemented in partially coherent in-line holography. T is allows the user to perform wide FOV imaging (across 4.5 mm) of pathology samples with image quality suffi cient for clinical diagnosis. T e holographically reconstructed image can be focused digitally at any depth within the object FOV aſt er image capture. It is also digitally corrected for artifacts arising from uncontrolled tilting and height variations between the sample and sensor planes.
Our results constitute the first demonstration of three- dimensional (3D) pathology slide imaging using on-chip microscopy. Using this lens-free on-chip microscope, the following observations have been made: invasive carcinoma cells were imaged within human breast sections, Papanicolaou smears were analyzed consistent with a high-grade squamous intraepithelial lesion, and sickle cell anemia blood smears were assessed. Blood smears could be examined over a large FOV of 20.5 mm 2 , more than 100-fold larger than a traditional light microscope. The resulting wide-field lens-free images were shown to have sufficient image resolution and contrast for clinical diagnosis in a blind test by an expert pathologist. Lens-free computational microscopy on a chip could have an important translational impact on the practice of pathology in resource-limited clinical settings. This cost-effective microscope not only records high-quality images over a wide FOV, but also retrieves the complex optical field of the specimen such that the pathologist can digitally adjust the focus of the sample after image capture. This provides a “virtual” depth-of- field experience for investigating sample slides, matching the manual depth adjustment that is routinely practiced in
www.microscopy-today.com • 2015 September
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