A drop of blood

US researchers have developed a microfluidic device that can isolate plasma from whole blood, bringing the notion of point-of-care blood analysis a step closer. 

Developing miniaturised portable devices to analyse biological fluids is an important move towards enabling rapid, low-cost clinical diagnosis. Currently such devices require filtration technologies, such as filter paper or microporous membranes, which are not easy to integrate with microfabrication techniques. 

Timothy Crowley and Vincent Pizziconi from Arizona State University, US, have come up with an original approach to overcome this. By precisely machining microfilters that work via 
capillary action, the researchers have been able to control the geometries of the pores and channels within their microfilters. This has allowed them to optimise the design of the filters so that they can effectively isolate nanolitre volumes of plasma from a single drop of blood. 

Caroline Moore