Page 364 - Sensors and Control Systems in Manufacturing

Advanced Sensors in Pr ecision Manufacturing
6.29 Sensors for Biomedical Technology 319
In recent years, advanced imaging and other computer-related tech-
nology have greatly expanded the horizons of basic biological and
biochemical research. Currently, such drivers as the growing needs
for environmental information and increased understanding of
genetic systems have provided impetus to biotechnology develop-
ment. This is a relatively new specialty in the marketplace; neverthe-
less, the intensity of worldwide competition is escalating. Collabora-
tive research and development projects among the U.S. government,
industry, and academia constitute a major thrust for rapid deploy-
ment of research and development. The results can place the nation
in a position of world leadership in biotechnology.

6.29.1 Sensor for Detecting Minute Quantities of Biological
Materials
A new device based on laser-excited fluorescence provides unparal-
leled detection of biological materials for which only minuscule sam-
ples may be available. This device, invented at the Ames Laborato-
ries, received a 1991 R&D 100 award.
The Ames Microfluor detector was developed to meet a need for
an improved detection technique, driven by important new studies
of the human genome, abuse substances, toxins, DNA adduct forma-
tion, and amino acids, all of which may be available only in minute
amounts. Although powerful and efficient methods have been devel-
oped for separating biological mixtures in small volumes (i.e., capil-
lary electrophoresis), equally powerful techniques for subsequent
detection and identification of these mixtures have been lacking.
The Microfluor detector combines very high sensitivities with the
ability to analyze very small volumes. The instrument design is based
on the principle that many important biomaterials are fluorescent,
while many other biomaterials, such as peptides and oligonucle-
otides, can be made to fluoresce by adding a fluorescent tag.
When a sample-filled capillary tube is inserted into the Micro-
fluor detector and is irradiated by a laser beam, the sample will fluo-
resce. The detector detects, monitors, and quantifies the contents by
sensing the intensity of the fluorescent light emitted. The signal is
proportional to the concentration of the materials. The proportional-
ity constant is characteristic of the material itself.
Analyses can be performed with sample sizes 50 times smaller
than those required by other methods, and concentrations as low as
10 molar (1 part per trillion) can be measured. Often, the critical
–11
components in a sample are present at these minute concentrations.
These two features make the Microfluor detector uniquely compati-
ble with capillary electrophoresis. In addition, the Ames-developed
detector is distinct from other laser-excited detectors in that it is not