Sensors for Environmental Control
A particularly productive source of spinoff products and processes
is the Small Business Innovation Research (SBIR) program, which
was established by Congress with two objectives: to increase
participation of small businesses in federal high technology
R&D activities, and to stimulate conversion of government-funded
research into commercial applications.
NASA's SBIR program has been eminently successful. It provides
NASA an additional source-beyond traditional aerospace companies-of
R&D talent and innovative thought. Hundreds of new systems
and components that advance NASA's capabilities have emerged
from the SBIR program. On the other side of the coin, NASA SBIR
contracts give small businesses opportunities to hone their R&D
skills and expand their technological capabilities, and in many
cases an SBIR assignment leads to a contractor's development,
with private capital, of a commercially useful product or process.
A plant technician monitors an industrial process stream to
assure that the effluent water's pH level is in compliance with
environmental regulations. Recently introduced to the commercial
market by GEO-CENTERS, Inc. the pH sensing system exemplifies
the broad range of spinoff products emerging from the NASA Small
Business Innovation Research program.
An example of environment-related research that led to commercialization
of new types of sensors is the SBIR collaboration of Kennedy
Space Center (KSC) with GEO-CENTERS, Inc., Newton Centre, Massachusetts.
GEO-CENTERS is a company dedicated to basic and application-oriented
R&D over a broad spectrum of technological disciplines. The
company has special capabilities in designing fiber optic sensors
for such applications as measurement and characterization of
industrial processes, remote sensing of chemical/biological hazards,
and environmental monitoring.
KSC's initial SBIR contract with GEO-CENTERS (1990) sought
development of an instrument for use in space life support research
(investigation of the air/water recycling potential of certain
plants). An important element of such research is accurate measurement
of the hydroponic culture's pH factor, an indication of the acidity
or alkalinity level of a solution. NASA was interested in an
advanced type of sensor known as an "optrode," the
optical-based equivalent of the glass pH electrode. A series
of optrodes would provide information about maintaining the proper
conditions for the plants' survival in a "space greenhouse."
Over a two-year span, GEO-CENTERS successfully developed an
optrode for NASA use and, since the instrument clearly had strong
commercial potential, embarked on development of a PC Based pH
Monitoring System for industrial use.
Now commercially available, the system employs a proprietary
fiber optic sensor (the optrode) to enable long term continuous
monitoring of the pH level of fluids in both standing and flowing
conditions. In addition to the optrode, the system includes an
opto-electronic (printed circuit) board, equipped with light
sensors and detectors, that fits into a standard desktop computer;
and a fiber optic cable connecting the circuit board and optrode
through which communications (light signals) are relayed. The
optoelectronics board supplies energy to the optrode and converts
the optrode's optical signals to electrical signals. System software
provides pH display, data logging, calibration and diagnostic
functions.
A typical application is monitoring the pH of an industrial
process stream to assure that the pH values of the effluent discharged
from the plant are within the acceptable range specified by the
Environmental Protection Agency. Normally, groundwater has a
pH of 5.5 to 7.5; when used in chemical processing, the pH level
can fall outside the normal limits and become harmful to fish
and wildlife. Therefore, the pH level of a process stream must
be continuously monitored to verify acceptability and, if it
is not in compliance, it must be restored to the acceptable range.
GEO-CENTERS literature cites a number of advantages of the
fiber optic pH monitor: low maintenance, long term calibration
stability, high resistance to biological/chemical fouling, and
immunity to electromagnetic interference caused by radio waves,
lightning, motors or generators, because the system is optically
based rather than electrically based. In addition, the optrode
can operate in solutions with very low conductivity, an important
factor in the measurement of very clean-hence low conductivity-boiler
water at power plants.
In 1993, when development of the commercial pH sensor was
in progress, KSC awarded GEO-CENTERS another SBIR contract related
to space recycling research, this one for a sensor capable of
continuously monitoring dissolved ammonia in a bioreactor and
an aquaculture. This development was successfully accomplished
in 1995 and commercialized with the first deliveries late in
that year.
The ammonia sensor employs the same general configuration
as the pH sensor, including a replaceable sensing element and
the computer-compatible opto-electronic board. The application,
however, is different: it is intended for monitoring bioreactors
rather than process streams. Bioreactors are complex systems
containing biological components (bacteria, yeast, mammalian
cells). Used to synthesize compounds, such as pharmaceuticals,
bioreactors must maintain colonies of living organisms whose
density and health determine the ultimate productivity of the
reactor. The ammonia concentration-along with pH-is one of the
important variables that must be controlled to assure proper
conditions for maintaining a colony. There is, says GEO-CENTERS,
no other means available for continuously monitoring ammonia
levels in a bioreactor and the company sees a significant potential
market for its ammonia sensor.
|