HOW IT WORKS

Backgrounded Membrane Imaging

Fast, Accurate and Fully Automated Subvisible Particle Analysis for 96 Samples in Under 2 Hours.

The Horizon^® and Aura^™ instrument’s primary analytical technique is Backgrounded Membrane Imaging (BMI). BMI has its roots in membrane microscopy, the old USP 788 subvisible particle lot release method where samples are filtered through a membrane and captured particles are manually counted using a microscope.

BMI reinvents membrane imaging with modern robotics, image processing and novel optics in a 96 well filter plate format that works just like a plate reader.

Backgrounded Images: The Heart of BMI

Backgrounded Membrane Imaging (BMI) uses sophisticated image processing techniques to analyze images and acquire particle data. The key is to first take a background image of the membrane. After samples are filtered through and particles are captured, the same membrane is re-imaged, this time with particles on the surface. The “background image” is precisely aligned with the “measure image” and then subtracted on a pixel by pixel basis so that the background texture is eliminated and particles are revealed. Refractive index contrast in BMI is 10x greater than measurements done in liquid as is the case with light obscuration and flow imaging, offering the increased sensitivity required to conduct robust early stage particulate detection. Particle sizes are calibrated with an electron microscope and analysis is fully automated.

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Comparison of BMI to Light Obscuration and Flow Imaging
	BMI	Light Obscuration	Flow Imaging
Low Volume Requirements	Requires 5 µL – 100X less than competition.	Requires 5 mL	Requires 500 µL
Highly Reproducible	CVs of polydisperse samples under 6%.	Highly variable on polydisperse samples.	Highly variable on polydisperse samples.
Consumable	ZERO particle carry over, ZERO cross contamination and ZERO washing.	Multiple components that require washing.	Expensive flow cell that requires washing.
High Refractive Index Contrast (High Sensitivity)	Dry based measurment = analyze small and dim particles with higher fidelity.	Low contrast, liquid based measurement.	Low contrast, liquid based measurement.
Fluidics Free	ZERO purge volume, ZERO leaking, ZERO clogging.	Fluidics-based.	Fluidics-based.
No Confounding “Particles”	Air bubbles are not measured..	Air bubbles counted as particles.	Air bubbles counted as particles.
Instrument Compatibility	Particles on membrane can be analyzed later with other instruments.	Sample ends up in waste, no additional analysis possible.	Sample ends up in waste, no additional analysis possible.