Micro X-ray Computed Tomography (Micro-CT)

X-ray computed tomography (often referred to as Micro-CT due to its spatial resolution) is a non-contact, non-destructive 2D and 3D imaging technique used to capture morphology and topography at the micron scale of the exterior and interior of the sample.

Covalent uses a best-in-class benchtop Micro-CT instrument, the CT Lab HX130. Covalent’s tool is the only HX130 system available for service in North America outside of Rigaku Corporation.

Strengths

• High spatial resolution of 2D images and subsequent 3D models
• Easily accesses interior structures and buried topographies in both industrial and biological samples
• Minimal to no sample preparation is required
• Nondestructive analysis

Limitations

• Resolution depends on sample size, shape and composition
• Post-processing can take significantly longer than measurement times

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Example Outputs Instruments Used How Micro-CT Works

• Solid phase
• Maximum dimension (x, y, or z): 10 mm (larger samples can impede resolution)
• Plate-like or discus sample geometries can also limit resolution

Micro- X-ray Computed Tomography works on the same premise as computed tomography scans in medicine (more commonly called “CT Scans” or “CAT Scans”), but on much smaller analytical volumes.

Tomography encompasses the reconstruction of a 3D model from serial cross-sectional images. In Micro-CT, these cross sections are generated from transmitted X-rays which pass through the sample to reach a 2D area detector.

The system records the intensity of x-ray signal at each pixel in a sensor array, forming a 2D planar projection of the sample’s relative density and material matrix. The resolution and sensitivity of this technique is critically dependent on the detection system and the nature of the sample determines the x-ray beam energy needed. The sample stage is rotated between measurements to produce a series of radial cross sections which the Micro-CT then assembles into a 3D model which can then be quantitatively measured to analyze critical dimensions of surface and subsurface components.

The 3D model contains the full data set of all measurable points within the probed volume, and can be explored virtually to characterize the spatial relations of various features in the sample, to extract 2D images at specific positions and angles, to find hidden differences between seemingly identical samples, and to calculate porosity and other properties: all without damaging or contacting the original sample.