Part B | 18.5
432 Part B Autonomous Ocean Vehicles, Subsystems and Control
which was developed in the mid 1950s for counting
and sizing red blood cells. In modern flow cytometers,
cells are typically analyzed at rates up to a few thousand per second. Sensors measure cellular features and
the corresponding signals are processed. These instruments have revolutionized automated cell analyses in
that measurements are made at high speed. Miniaturization of the systems is rapidly occurring and shipboard,
flow-through versions are now commercially available.
The analysis of the intrinsic fluorescence profiles of
individual marine algae can be used in general classification of organisms based on cell size and fluorescence
properties.
Commercially available ocean deployable systems
exist, including FlowCAM from Fluid Imaging Technologies. These instruments preform continuous imaging particle analysis, monitoring phytoplankton, zooplankton, and fluid borne particulates. The FlowCam
is available in submersible models which can measure
particles from 1 m to 3 mm in size, which make it
a good candidate for adoption onto AUVs. The FlowCytobot is a separate system that uses diode-pumped
532 nm lasers and can measure scattering and fluorescence of bio-particles. The FlowCytobot is currently
designed for operation in coastal observatories with
a connection to the shore for power. A next generation system has evolved, which is an imaging FlowCytobot version for imaging with a higher sampling
throughput. The work to move these systems into more
portable formats, capable of being carried on vehicles,
is occurring outside the traditional ocean engineering
field. Currently, lab-based engineering developments
of optofluidic flow cytometers are underway primarily
within the medical or clinical diagnostics arena. The
field of optofluidics is comprised of optics and microfluidics working together to create novel functionalities
within a small chip. These chips hold great promise for
lab-on-a-chip flow cytometry and for the further miniaturization of the flow cytometer [18.27]. The Microflow
cytometer has been developed on a chip for the characterization of phytoplankton. The Microflow cytometer
measures distinct side scatter and fluorescence properties of various microorganisms. This device proved sensitive enough to detect and characterize picoplankton
with diameters 1 m and larger phytoplankton up to
80 m in length. The wide range in size discrimination
coupled with the detection of intrinsic fluorescent pigments suggests that this Microflow cytometer should be
able to distinguish different populations of phytoplankton as a miniaturized system on unmanned underwater
vehicles.
It is hoped that highlighting these systems indicates
the emergence of biological sensor technologies on
mobile platforms. A large number of microbial biosensors have been developed for environmental, food, and
biomedical applications, which we can expect to transition over to systems engineered for the ocean. The
fabrication of microbial biosensors based on amperometry, potentiometry, conductometry, voltammetry, microbial fuel cell, fluorescence, bioluminescence, and
colorimetry, is occurring and will be applied in the
field. Sensors that provide reliable quantitative information related to growth rates are coming with the
expansion of low cost, high performance embedded microscopy systems. Detection and data presentation of
kinetic information allows direct and indirect indicators for quantitative predictions for the ecosystem being
monitored. Sensors such as spectral optical instruments
continue to evolve and help detect the initiation and extent of primary production. These spectral instruments
are successful in connecting environmental perturbations and variations with primary production events in
real time. The increased number and quality of underwater mobile imaging systems (beyond acoustics
only) is helping track levels of predation to tease out
changes in population numbers. These predation data
give insight into the ecosystem’s structural dynamics
and helps researchers to better understand the impacts
of environmental changes. For many of the biosensor designs outlined in this section the utilization of
micro electro-mechanical (MEMS)-based underwater
sensor system designs should be a major part of the
future scope for research. MEMs-based sensors will optimize the cost of materials and energy in particular.
One other potential dimension of underwater biosensor development is the bio-inspired system approach,
which uses the existing biological system around us.
The oceans in particular are a rich depository of ideas
and solutions ready for adaptation to our man-made
systems. Bio-inspired sensor systems, like bio-inspired
AUVs, are not just about trying to imitate the living system but to synergize the currently available
technology with nature to optimize any given sensor
design.
18.5 Physical Sensor Systems
Physical sensor technologies for energy, heat, water,
salt, and particulate phases in general are more mature
than either chemical or biological sensor technologies.
A large industrial base exists for the manufacture of
432 Part B Autonomous Ocean Vehicles, Subsystems and Control
which was developed in the mid 1950s for counting
and sizing red blood cells. In modern flow cytometers,
cells are typically analyzed at rates up to a few thousand per second. Sensors measure cellular features and
the corresponding signals are processed. These instruments have revolutionized automated cell analyses in
that measurements are made at high speed. Miniaturization of the systems is rapidly occurring and shipboard,
flow-through versions are now commercially available.
The analysis of the intrinsic fluorescence profiles of
individual marine algae can be used in general classification of organisms based on cell size and fluorescence
properties.
Commercially available ocean deployable systems
exist, including FlowCAM from Fluid Imaging Technologies. These instruments preform continuous imaging particle analysis, monitoring phytoplankton, zooplankton, and fluid borne particulates. The FlowCam
is available in submersible models which can measure
particles from 1 m to 3 mm in size, which make it
a good candidate for adoption onto AUVs. The FlowCytobot is a separate system that uses diode-pumped
532 nm lasers and can measure scattering and fluorescence of bio-particles. The FlowCytobot is currently
designed for operation in coastal observatories with
a connection to the shore for power. A next generation system has evolved, which is an imaging FlowCytobot version for imaging with a higher sampling
throughput. The work to move these systems into more
portable formats, capable of being carried on vehicles,
is occurring outside the traditional ocean engineering
field. Currently, lab-based engineering developments
of optofluidic flow cytometers are underway primarily
within the medical or clinical diagnostics arena. The
field of optofluidics is comprised of optics and microfluidics working together to create novel functionalities
within a small chip. These chips hold great promise for
lab-on-a-chip flow cytometry and for the further miniaturization of the flow cytometer [18.27]. The Microflow
cytometer has been developed on a chip for the characterization of phytoplankton. The Microflow cytometer
measures distinct side scatter and fluorescence properties of various microorganisms. This device proved sensitive enough to detect and characterize picoplankton
with diameters 1 m and larger phytoplankton up to
80 m in length. The wide range in size discrimination
coupled with the detection of intrinsic fluorescent pigments suggests that this Microflow cytometer should be
able to distinguish different populations of phytoplankton as a miniaturized system on unmanned underwater
vehicles.
It is hoped that highlighting these systems indicates
the emergence of biological sensor technologies on
mobile platforms. A large number of microbial biosensors have been developed for environmental, food, and
biomedical applications, which we can expect to transition over to systems engineered for the ocean. The
fabrication of microbial biosensors based on amperometry, potentiometry, conductometry, voltammetry, microbial fuel cell, fluorescence, bioluminescence, and
colorimetry, is occurring and will be applied in the
field. Sensors that provide reliable quantitative information related to growth rates are coming with the
expansion of low cost, high performance embedded microscopy systems. Detection and data presentation of
kinetic information allows direct and indirect indicators for quantitative predictions for the ecosystem being
monitored. Sensors such as spectral optical instruments
continue to evolve and help detect the initiation and extent of primary production. These spectral instruments
are successful in connecting environmental perturbations and variations with primary production events in
real time. The increased number and quality of underwater mobile imaging systems (beyond acoustics
only) is helping track levels of predation to tease out
changes in population numbers. These predation data
give insight into the ecosystem’s structural dynamics
and helps researchers to better understand the impacts
of environmental changes. For many of the biosensor designs outlined in this section the utilization of
micro electro-mechanical (MEMS)-based underwater
sensor system designs should be a major part of the
future scope for research. MEMs-based sensors will optimize the cost of materials and energy in particular.
One other potential dimension of underwater biosensor development is the bio-inspired system approach,
which uses the existing biological system around us.
The oceans in particular are a rich depository of ideas
and solutions ready for adaptation to our man-made
systems. Bio-inspired sensor systems, like bio-inspired
AUVs, are not just about trying to imitate the living system but to synergize the currently available
technology with nature to optimize any given sensor
design.
18.5 Physical Sensor Systems
Physical sensor technologies for energy, heat, water,
salt, and particulate phases in general are more mature
than either chemical or biological sensor technologies.
A large industrial base exists for the manufacture of