Stephen Arnold
Polytechnic Institute of New York University

From the Death of an Icon to the Birth of a Physical Principle
for ultra-sensitive label-free Bio-sensing

The announcement (in 2002) that the death of my favorite teacher and arguably the world’s most prolific science fact and fiction writer (Asimov, >500 books) had been from an HIV infection (contracted during open heart surgery) redirected my laboratory’s efforts to inventing a means for immediate detection of individual virions in blood. Although trials in serum may not have begun, the physical principle that evolved is likely the most ubiquitous approach for research in ultra-sensitive label-free sensing of bio-monolayers and individual bio-particles.
I will trace the evolution of the so-called Reactive Sensing Principle (RSP) in Micro-cavity frequency shift detection from its inception in 2003, and discuss its intimate connection to Opto-mechanics.
Finally, by marrying Micro-photonics with Nano-optics, specifically a Whispering Gallery Mode Resonator and a Nano-Plasmonic Enhancing Epitope we have recently managed to detect cancer marker protein molecules one at a time, and pushed the label-free limit of detection to the unprecedented level of 10 zepto-grams (5 kDa) in solution. This is less than one-hundredth the mass of all known virus, and lower than the mass of existing cancer markers.