A microfluidic imaging method that could be incorporated into a hand-held microscope may be a significant step forward for medicine in the developing world.

Changhuei Yang, Xin Heng and colleagues from the California Institute of Technology, Pasadena, US, have developed a technique known as optofluidic microscopy (OFM), which they claim could help doctors to diagnose malaria more quickly.

The lensless OFM device uses lab-on-a-chip technology to image a sample with high resolution; Yang hopes that it will be made into a hand-held device to screen cells. At the moment a conventional microscope is needed to look for infected cells in a laboratory sample. The process can be both labour intensive and time consuming. 'This bulky and expensive microscope can be replaced by a cheap OFM device that a doctor can easily carry in his pocket,' Yang said.

OFM is based on an array of sensors on a chip covered by a layer of metal, etched with small holes. The sample is passed over the metal through a microfluidic channel and imaged through the holes.

'The novel geometric arrangement of the holes ensures that each hole maps uniquely onto individual pixels. That's the key to the operation of this optofluidic microscope,' explains Yang. 'In this case, the hole size defines the resolution. With existing technology, we can fabricate holes down to tens of nanometres with relative ease. This means we can potentially provide resolution that is better than that of a conventional microscope.'

Yang hopes that the use OFM will change the way bioscience and clinical work is done in the future. 'It has the dual advantage of compactness and low cost,' he said.

Ruth Needham