01-10-2012, 04:52 PM
Recent Development in Optical Fiber Biosensors
[attachment=34958]
Abstract:
Remarkable developments can be seen in the field of optical fibre biosensors in
the last decade. More sensors for specific analytes have been reported, novel sensing
chemistries or transduction principles have been introduced, and applications in various
analytical fields have been realised. This review consists of papers mainly reported in the
last decade and presents about applications of optical fiber biosensors. Discussions on the
trends in optical fiber biosensor applications in real samples are enumerated.
Introduction
Biosensor development is driven by the continuous need for simple, rapid, and continuous in-situ
monitoring techniques in a broad range of areas, e.g. medical, pharmaceutical, environmental, defense,
bioprocessing, or food technology.
Biosensors make use of biological components in order to sense a species of interest (which by itself
need not be a “biospecies”). On the other side, chemical sensors not using a biological component but
placed in a biological matrix are not biosensors by definition. Biological systems (such as tissues, micro-organisms, enzymes, antibodies, nucleic acids, etc.) when combined with a physico-chemical
transducer (optical, electrochemical, thermometric, piezoelectric) form a biosensor.
On the other hand, the development of optical-fiber sensors during recent years is related to two of
the most important scientific advances: the laser and modern low-cost optical fibers. Recently, optical
fibers have become an important part of sensor technology. Their use as a probe or as a sensing
element is increasing in clinical, pharmaceutical, industrial and military applications. Excellent light
delivery, long interaction length, low cost and ability not only to excite the target molecules but also to
capture the emitted light from the targets are the main points in favour of the use of optical fibers in
biosensors.
Absorbance measurements
The simplest optical biosensors use absorbance measurements to determine any changes in the
concentration of analytes that absorb a given wavelength of light. The system works by transmitting
light through an optical fiber to the sample; the amount of light absorbed by the analyte is detected
through the same fiber or a second fiber. The biological material is immobilized at the distal end of the
optical fibers and either produces or extracts the analyte that absorbs the light.
A fiber optic pH sensor [1] and a fiber optic oxygen sensor [2] have been developed by Wolthuis et
al., for use in medical applications. In the first case, the sensor uses an absorptive indicator compound
with a long wavelength absorption peak near 625 nm; change in absorption over the pH range
6.8 to 7.8 is reasonably linear. The sensor is interrogated by a pulsed, red LED. Return light signal is
split into short and long wavelength components with a dichroic mirror; the respective signals are
detected by photodiodes, and their photocurrents are used to form a ratiometric output signal. In
laboratory tests, the sensor system provided resolution of 0.01 pH and response time of 30-40 s.
Following gamma sterilization, laboratory sensor testing with heparinised human blood yielded
excellent agreement with a clinical blood gas analyzer. Excellent sensor performance and low cost,
solid-state instrumentation are hallmarks of this sensor-system design.
Absorbance measurements
The simplest optical biosensors use absorbance measurements to determine any changes in the
concentration of analytes that absorb a given wavelength of light. The system works by transmitting
light through an optical fiber to the sample; the amount of light absorbed by the analyte is detected
through the same fiber or a second fiber. The biological material is immobilized at the distal end of the
optical fibers and either produces or extracts the analyte that absorbs the light.
A fiber optic pH sensor [1] and a fiber optic oxygen sensor [2] have been developed by Wolthuis et
al., for use in medical applications. In the first case, the sensor uses an absorptive indicator compound
with a long wavelength absorption peak near 625 nm; change in absorption over the pH range
6.8 to 7.8 is reasonably linear. The sensor is interrogated by a pulsed, red LED. Return light signal is
split into short and long wavelength components with a dichroic mirror; the respective signals are
detected by photodiodes, and their photocurrents are used to form a ratiometric output signal. In
laboratory tests, the sensor system provided resolution of 0.01 pH and response time of 30-40 s.
Following gamma sterilization, laboratory sensor testing with heparinised human blood yielded
excellent agreement with a clinical blood gas analyzer. Excellent sensor performance and low cost,
solid-state instrumentation are hallmarks of this sensor-system design.
Fluorescence measurements
Fluorescence techniques provide sensitive detection of biomolecules. Furthermore, since
fluorescence intensity is proportional to the excitation intensity, even weak signals can be observed. In
last decade reagentless fiber-based biosensors have been developed. These biosensors are capable of
detecting changes in cell behaviour, metabolism and cell death when exposed to toxic agents.
Fluorescence measurements are not used as often as absorbance and reflectance with enzyme optical
fiber-based biosensors, as it is not common for enzyme reactions to produce fluorescent products or
intermediates. Most fluorescence techniques employ a fluorescent dye to indirectly monitor formation
or consumption of a transducer.
[attachment=34958]
Abstract:
Remarkable developments can be seen in the field of optical fibre biosensors in
the last decade. More sensors for specific analytes have been reported, novel sensing
chemistries or transduction principles have been introduced, and applications in various
analytical fields have been realised. This review consists of papers mainly reported in the
last decade and presents about applications of optical fiber biosensors. Discussions on the
trends in optical fiber biosensor applications in real samples are enumerated.
Introduction
Biosensor development is driven by the continuous need for simple, rapid, and continuous in-situ
monitoring techniques in a broad range of areas, e.g. medical, pharmaceutical, environmental, defense,
bioprocessing, or food technology.
Biosensors make use of biological components in order to sense a species of interest (which by itself
need not be a “biospecies”). On the other side, chemical sensors not using a biological component but
placed in a biological matrix are not biosensors by definition. Biological systems (such as tissues, micro-organisms, enzymes, antibodies, nucleic acids, etc.) when combined with a physico-chemical
transducer (optical, electrochemical, thermometric, piezoelectric) form a biosensor.
On the other hand, the development of optical-fiber sensors during recent years is related to two of
the most important scientific advances: the laser and modern low-cost optical fibers. Recently, optical
fibers have become an important part of sensor technology. Their use as a probe or as a sensing
element is increasing in clinical, pharmaceutical, industrial and military applications. Excellent light
delivery, long interaction length, low cost and ability not only to excite the target molecules but also to
capture the emitted light from the targets are the main points in favour of the use of optical fibers in
biosensors.
Absorbance measurements
The simplest optical biosensors use absorbance measurements to determine any changes in the
concentration of analytes that absorb a given wavelength of light. The system works by transmitting
light through an optical fiber to the sample; the amount of light absorbed by the analyte is detected
through the same fiber or a second fiber. The biological material is immobilized at the distal end of the
optical fibers and either produces or extracts the analyte that absorbs the light.
A fiber optic pH sensor [1] and a fiber optic oxygen sensor [2] have been developed by Wolthuis et
al., for use in medical applications. In the first case, the sensor uses an absorptive indicator compound
with a long wavelength absorption peak near 625 nm; change in absorption over the pH range
6.8 to 7.8 is reasonably linear. The sensor is interrogated by a pulsed, red LED. Return light signal is
split into short and long wavelength components with a dichroic mirror; the respective signals are
detected by photodiodes, and their photocurrents are used to form a ratiometric output signal. In
laboratory tests, the sensor system provided resolution of 0.01 pH and response time of 30-40 s.
Following gamma sterilization, laboratory sensor testing with heparinised human blood yielded
excellent agreement with a clinical blood gas analyzer. Excellent sensor performance and low cost,
solid-state instrumentation are hallmarks of this sensor-system design.
Absorbance measurements
The simplest optical biosensors use absorbance measurements to determine any changes in the
concentration of analytes that absorb a given wavelength of light. The system works by transmitting
light through an optical fiber to the sample; the amount of light absorbed by the analyte is detected
through the same fiber or a second fiber. The biological material is immobilized at the distal end of the
optical fibers and either produces or extracts the analyte that absorbs the light.
A fiber optic pH sensor [1] and a fiber optic oxygen sensor [2] have been developed by Wolthuis et
al., for use in medical applications. In the first case, the sensor uses an absorptive indicator compound
with a long wavelength absorption peak near 625 nm; change in absorption over the pH range
6.8 to 7.8 is reasonably linear. The sensor is interrogated by a pulsed, red LED. Return light signal is
split into short and long wavelength components with a dichroic mirror; the respective signals are
detected by photodiodes, and their photocurrents are used to form a ratiometric output signal. In
laboratory tests, the sensor system provided resolution of 0.01 pH and response time of 30-40 s.
Following gamma sterilization, laboratory sensor testing with heparinised human blood yielded
excellent agreement with a clinical blood gas analyzer. Excellent sensor performance and low cost,
solid-state instrumentation are hallmarks of this sensor-system design.
Fluorescence measurements
Fluorescence techniques provide sensitive detection of biomolecules. Furthermore, since
fluorescence intensity is proportional to the excitation intensity, even weak signals can be observed. In
last decade reagentless fiber-based biosensors have been developed. These biosensors are capable of
detecting changes in cell behaviour, metabolism and cell death when exposed to toxic agents.
Fluorescence measurements are not used as often as absorbance and reflectance with enzyme optical
fiber-based biosensors, as it is not common for enzyme reactions to produce fluorescent products or
intermediates. Most fluorescence techniques employ a fluorescent dye to indirectly monitor formation
or consumption of a transducer.