Camera-based blood test system delivers results in 15 minutes

Engineers at Biosurfit have developed a compact desktop blood analyzer called the "spinit" that could be used in doctors' offices.

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Engineers at Biosurfit (www.biosurfit.com) have developed a compact desktop blood analyzer called the "spinit" that could be used in doctors' offices.

Using a combination of Point Grey cameras, proprietary software, and DVD-style test cartridges, the spinit takes one small drop of blood, analyzes it, and gives precise results within 15 min.

The CD-like cartridge in the spinit incorporates several detection zones that include a biological recognition layer (BRL), which contains antibody fragments immobilized on a gold surface that acts as a selective trap for a specific blood biomarker.

When placed in the spinit reader, the cartridge spins to a predetermined velocity and the centrifugal force pushes the blood sample through the microfluidic structures of the cartridge.

When a patient's blood passes through the BRL, biomarkers bind to immobilized antibody fragments. To determine the concentration of biomarkers, the spinit uses surface plasmon resonance (SPR), a well-established spectrometry technique that enables molecular changes on the cartridge's biological recognition layer to be detected.

The system measures the refractive index of light reflecting off the gold surface of the cartridge. The light source used to illuminate the surface of the cartridge comprises a near-infrared wavelength laser, a polarizer, and a focusing lens. The optical detector uses a Point Grey Firefly MV FireWire monochrome camera acquiring images at nearly 160 frames/sec with a region of interest measuring 50 × 800 pixels.

The FireWire camera is triggered when a phototransistor behind a semi-opaque mirror detects a reflection coming from the detection zone on the cartridge. The camera then acquires 3000 images of each detection zone over a 10-min period.

When the biomarkers bind to the immobilized antibody fragments, they cause a noticeable refractive index change in the SPR signal, which is measured by the Firefly camera. This change in the SPR is then used to determine the concentration of biomarkers in the blood sample.

The spinit will be released later in 2012 and the first cartridge will measure C-reactive protein (CRP). CRP is an acute phase protein actively circulating in the body during an inflammatory response.

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