OPEN ACCESS Procedures
BioMERAplusCHEM sample safety form
BioMERAplusCHEM research infrastructure
The BioMERAplusCHEM research infrastructure consists of the following three main components: 1) a chemical mapping detector (Silicon Drift Detector [SDD]) for multimodal, correlated XRF and microCT data acquisition at high resolution (micrometers); (2) a laboratory XAS for speciation data on chemical elements; and (3) a phase contrast data acquisition capability in order to enable data acquisition on samples consisting of adjacent components with similar densities and weak absorption.
1. Silicon Drift Detector (SDD) for chemical mapping data using XRF: In order to provide correlated multimodal chemical and structural imaging data a Silicon Drift Detector (SDD) with the latest preamplifier technology has been integrated to the existing BioMERA microCT. The microCT provides the structural data, while the new BioMERAplusCHEM SDD provides the chemical data.
Technical details: The source has spot size down to 5 micron for measurements on small components and microstructures, the SDD has a vacuum preamplifier, low noise, for the energy range upto 10 keV, full width half maxima (FWHM) < 133 eV @ 1 µs peaking time for Mn Kα line, with signal processing electronics and accessories, digital pulse processor board-DPP3 with peaking time down to 25 ns and higher count rates resulting in reduced measuring time and repeatability.
Figure 1: Silicon Drift Detector (SDD)
2. X-ray Absorption Spectroscopy (XAS/XAFS) system for speciation data: Laboratory based XAS system equipped with an X-ray source covering an energy range from 4.5 to 20 keV. This type of user-friendly spectrometer can be used as an in-house supplement to expensive and limited access to the synchrotron facility beamlines enabling XAFS (X-ray absorption fine structure) measurements without using a synchrotron source. In addition to being a competitive alternative, this laboratory XAS instrument is truly complementary to the synchrotron, including where the sample/system needs to be studied over longer time or the samples that cannot be taken to the synchrotrons.
Technical details: XAS (hard x-ray monochromator) for high resolution x-ray absorption spectroscopy measurements with crystal analyzers, energy bandpass 600eV, resolving power 4000, constant over the full energy range, acquisition times ~8min, normalized to analyte concentration, x-ray shutter assembly with multipoint safety interlocks. Hybrid photon counting detector for direct detection of x-ray photons combined with single-photon counting, sensor 1028x512 pixels, Pixel size 75x75. No readout noise or dark current for best signal-to-noise ratio. Dual energy discrimination for suppression of low and high energy background. Dead-time free readout.
Figure 2: BioMERAplusCHEM laboratory XAS system
3. High-resolution phase contrast imaging (HR-PCI detector) detector: High resolution phase contrast imaging (HR-PCI) now integrated to the existing BioMERA microCT overcomes the limitations of the attenuation-based microCT technique in characterizing weakly absorbing materials. The detection of phase effects in the X-ray that exits a sample along with the attenuated X-ray makes it possible to visualize morphological features in low absorbing materials like soft tissues, carbon composites, polymers, cloth and any other such materials comprised of low atomic number with weak absorption. The micro-focus source enables spatial coherence, and propagation-based phase contrast can be observed. A small pixel detector, 1650 x 1246, has been integrated to the microCT enabling the visualization of phase effects.
Technical details: A lightweight detector high resolution phase contrast imaging X-ray detector. The detector has gadolinium oxysulphide (Gd2O2S) scintillator screen, placed in direct contact with the photodiode array, converts incident X-ray photons to light, which in turn is detected by the photodiodes. The detector has a resolution of 20 um. The detector has active area of 1650x1246 pixels for imaging. The dynamic range of the detector is 2000:1. The active area of imaging is 33.0 x 24.9 mm. The image read out period is 680 ms.
Figure 3: BioMERAplusCHEM HR PCI detector
Funding Acknowledgement: This work was co-funded by the European Regional Development Fund and the Republic of Cyprus through the Research and Innovation Foundation project BioMERAplusCHEM (Grant No. OPEN INFRA/0625/0030).
