Easy Test for Sickle Cell Disease Developed

Sickle cell disease affects 25% of people living in Central and West Africa and, if left undiagnosed, can cause life threatening “silent” strokes and lifelong damage. However, ubiquitous testing procedures have yet to be implemented in these areas, necessitating a simple, rapid, and accurate testing platform to diagnose sickle cell disease.

Biomedical engineers from the University of Connecticut (Storrs, CT, USA) developed a label-free, sensitive, and specific testing platform using only a small blood sample of less than 1 μL based on the higher density of sickle red blood cells under deoxygenated conditions. Testing was performed with a lightweight and compact 3D-printed attachment installed on a commercial smartphone. This attachment includes a light-emitting diode (LED) to illuminate the sample, an optical lens to magnify the image, and two permanent magnets for magnetic levitation of red blood cells.

A small blood sample from the patient was mixed with a common, salt-based solution sodium metabisulfite that draws oxygen out of the sickle cells, making them denser and easier to detect. The sample is then loaded into a disposable micro-capillary that is inserted into the tester attached to the smartphone. Inside the testing apparatus the micro-capillary passes between two magnets that are aligned so that the same poles face each other and create a magnetic field.

The capillary is then illuminated with an LED that is filtered through a ground glass diffuser and magnified by an internal lens. The smartphone's built-in camera captures the resulting image and presents it digitally on the phone's external display. The blood cells are floating inside the capillary, whether higher floating healthy red blood cells or lower floating sickle cells, can then be easily observed. The device also provides clinicians with a digital readout that assigns a numerical value to the sample density to assist with the diagnosis. The entire process takes less than 15 minutes.

Stephanie M. Knowlton, PhD, the lead author of the study, said, “With this device, you're getting much more specific information about your cells than some other tests. Rather than sending a sample to a laboratory and waiting three days to find out if you have this disease, with this device you get on-site and portable results right away. We believe a device like this could be very helpful in developing countries where laboratory resources may be limited.” The study was published on October 22, 2015, in the journal Scientific Reports.

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