Directional Ejection of DNA Base Droplets (IMAGE) University of Southern California Caption Each reservoir contains a different base or 'letter' in the DNA alphabet. When activated, an acoustic membrane located underneath the membrane aims a tiny droplet of the desired letter to a point above the center of the array, to the surface of a slide (not shown) successive activations build up a DNA sample on the slide. Credit USC Ming Hsieh, department of electrical engineering Usage Restrictions must credit USC Ming Hsieh department of electrical engineering License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.