To download the latest issue
Jun 8th, 2010
New opto acoustic focusing technology stabilizes tiny biological samples
Purdue University researchers have developed a new method to fixate bacteria, viruses, and complex molecules like DNA inside liquid droplets by using both electric fields and laser light. The method may prove to be more effective and practical than separate light or sonic focusing units for mobile diagnostic sensors and forensic devices.
Ordinarily, the particles inside droplets are detected when they randomly fall on a sensor's surface. However, the new method could improve sensor efficiency by actively moving particles to specific regions on an electronic chip for detection or analysis.
Critical to the technology are electrodes made of indium tin oxide, a transparent and electrically conductive material commonly used in consumer electronics for touch-screen displays. Liquid drops are positioned on the electrodes, and the infrared laser heats up both the electrodes and the droplets. Then electric fields in the electrodes cause the heated liquid to produce a "microfluidic vortex" of circulating liquid. This vortex enables researchers to position the particles in the circulating liquid by moving the infrared laser. The particles accumulate only where the laser is shined.
More MEDTECH news