Dataset Information

Direct Detection Electron Energy-Loss Spectroscopy: A Method to Push the Limits of Resolution and Sensitivity.

ABSTRACT: In many cases, electron counting with direct detection sensors offers improved resolution, lower noise, and higher pixel density compared to conventional, indirect detection sensors for electron microscopy applications. Direct detection technology has previously been utilized, with great success, for imaging and diffraction, but potential advantages for spectroscopy remain unexplored. Here we compare the performance of a direct detection sensor operated in counting mode and an indirect detection sensor (scintillator/fiber-optic/CCD) for electron energy-loss spectroscopy. Clear improvements in measured detective quantum efficiency and combined energy resolution/energy field-of-view are offered by counting mode direct detection, showing promise for efficient spectrum imaging, low-dose mapping of beam-sensitive specimens, trace element analysis, and time-resolved spectroscopy. Despite the limited counting rate imposed by the readout electronics, we show that both core-loss and low-loss spectral acquisition are practical. These developments will benefit biologists, chemists, physicists, and materials scientists alike.

SUBMITTER: Hart JL

PROVIDER: S-EPMC5557959 | biostudies-other | 2017 Aug

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:Digital polymerase chain reaction (dPCR) is a powerful tool for genetic analysis, providing superior sensitivity and accuracy. In many applications that demand minuscule reaction volumes, such as single cell analysis, efficient and reproducible sample handling and digitization is pivotal for accurate absolute quantification of targets, but remains a significant technical challenge. In this paper, we described a robust and flexible microfluidic alternating-pull-push active digitization (?APPAD) strategy that confers close to 100% sample digitization efficiency for microwell-based dPCR. Our strategy employs pneumatic valve control to periodically manipulate air pressure inside the chip to greatly facilitate the vacuum-driven partition of solution into microwells, enabling efficient digitization of a small-volume solution with significantly reduced volume variability. The ?APPAD method was evaluated on both tandem-channel and parallel-channel chips, which achieved a digitization efficiency of 99.5 ± 0.3% and 94.6 ± 0.9% within 10.5 min and 2 min, respectively. To assess the analytical performance of the ?APPAD chip, we calibrated it for absolution dPCR quantitation of ?DNA across a range of concentrations. The results obtained with our chip matched well with the theoretical curve computed from Poisson statistics. Compared to the existing methods for highly efficient sample digitization, not only does our technology greatly reduce the constraints on microwell geometries and channel design, but also benefits from the intrinsic amenability of the pneumatic valve technique with device integration and automation. Thus we envision that the ?APPAD technology will provide a scalable and widely adaptable platform to promote the development of advanced lab-on-a-chip systems integrating microscale sample processing with dPCR for a broad scope of applications, such as single cell analysis of tumor heterogeneity and genetic profiling of circulating exosomes directly in clinical samples.

Dataset Information

Direct Detection Electron Energy-Loss Spectroscopy: A Method to Push the Limits of Resolution and Sensitivity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets