Page 366 - Sensors and Control Systems in Manufacturing

Advanced Sensors in Pr ecision Manufacturing
testing is needed, researchers now feel confident that the technique 321
and the detection sensor can detect precancerous conditions three to
four years before onset of the disease.
Working in collaboration with industry, researchers expect to
develop an instrument in several years for rapid automated comput-
erized screening of larger populations of smokers, miners, and other
people at risk of developing lung cancer. Because lung cancer is the
leading cancer killer in both men and women, a successful screening
procedure would dramatically lower the nation’s mortality rate from
the disease. A similar procedure has potential for the analysis of Pap
smears, now done by technicians who screen slides one at a time and
can misread them.
In addition to a successful screening program, LANL hopes to
develop an effective treatment for early lung cancer. The National
Cancer Institute will help investigate and implement both diagnostic
and therapeutic programs. Researchers are performing basic cell
studies on animals to investigate the effect of porphyrin on lung can-
cer cells. They are also exploring the use of the LANL-designed por-
phyrin attached to radioactive copper to kill early cancer cells in the
lung in a single search-and-destroy mission. The porphyrin not only
seeks out cancer cells but also has a molecular structure, similar to a
hollow golf ball, that can take certain metals into its center. A small
amount of radioactive copper 67 placed inside the porphyrin should
destroy tumors the size of pinhead, as well as function as a tracer.

6.29.3 Ultrasensitive Sensors for Single-Molecule Detection
Enhancing the sensitivity of research instruments has long been a
goal of physicists, biologists, and chemists. With the single-molecule
detector, researchers have achieved the ultimate in this pursuit: detec-
tion of a single fluorescent molecule in a liquid. The new instrument—
a thousand times more sensitive than existing commercial detectors—
brings new capabilities to areas of science and technology that affect
lives in many ways, from DNA sequencing, biochemical analysis,
and virus studies to identifying environmental pollutants.
For some time, scientists have observed individual molecules
trapped in a vacuum, where they are isolated and relatively easy to
find. However, many important biological and chemical processes
occur in a liquid environment, where many billions of other molecules
surround the molecules of interest. Developing a single-molecule
detector that operates in such an environment presented a difficult
challenge.
The observation technique involves attaching fluorescent dye
molecules to the molecules of interest and then exciting the dye mol-
ecule by passing them in solution to a rapidly pulsed laser beam and
detecting the subsequent faint light, or photons, they emit. The fluo-
rescent lifetimes of the molecules are much shorter than the time the