Biomedical Engineering Reference
In-Depth Information
related area in the design and development of porous silicon (PSi) interfaces that can carry
out size-selective detection of analytes is how to better exploit the “bulk filtration” prop-
erties of the PSi matrix. However, developing viable biological interfaces requires addi-
tional fundamental studies in determining the stability of the system response.
The types and classes of materials used as the primary building blocks of biological-
based sensors are also being expanded. A number of biosensor designs exploit neuronal
tissue networks as the basic sensing element. These broadband biosensors provide elec-
trophysiological and morphological data, and have been investigated for monitoring tox-
ins. The networks can be applied in early warning systems for environmental threat
detection. In addition, specialized materials such as bacteriorhodopsin (bR) are finding
applications in many types of sensing platforms using light or voltage modulation. These
include light-sensitive detectors, photocells, motion sensors, artificial retinas, and bioelec-
tronic devices. Site-directed and semirandom mutagenesis can provide novel properties
for custom building bR devices.
Biosensor technology is quickly filling an important niche in health and medicine by
enabling rapid monitoring of pathogens and viruses. Advanced developments in biosen-
sor arrays for toxicity monitoring and screening will provide the enhanced ability of rec-
ognizing and classifying specific chemical or biological toxins.
A window into future research directions and anticipated advances in biosensor devel-
opment are presented in the final sections of this chapter. Through personal communica-
tion several contributors to the volume have offered their perspectives and insight to this
dynamic discipline. The perspectives and comments are provided by leading researchers
such as Ashok Mulchandani, Anthony P.F. Turner, Ulrich J. Krull, Claudio Nicolini, Won-
Yong Lee, and Brian Cullum. The identified areas of key importance in the future are
innovative technologies to enhance sensitivity and selectivity, achieve biomimetic sensor
designs, develop optical nucleic acid sensors, utilize nanostructured organic biological
matrices, exploit the functional capabilities of carbon nanotubes (CNTs), and rapidly
advance medical research. Finally, Felix T. Hong's comments on reverse engineering
biology challenges us to question our views on smart technology and whether embedded
human-like intelligence is really possible in artificial devices and products. It is hoped
that the following more speculative presentations will spur vigorous discussions and
provide young researchers with valuable insight into future research directions. This
presentation may also be of interest to individuals who wish to see a snap shot of views
expressed by experts and leading-edge researchers in the early part of the twenty-first
century.
23.2
New Directions of Research
23.2.1
Enhancing Sensitivity and Selectivity
Ashok Mulchandani (personal communication, 2005) and his colleagues associated with
the University of California at Riverside remind us of the continual need to increase
biosensor sensitivity and selectivity. Consider the area of clinical chemistry analysis that
has received a great deal of attention over the past 30 years. Biosensors for the measure-
ments of blood metabolites such as glucose, lactate, and urea, using both electrochemical
and optical modes of transduction, are available commercially for point-of-care settings
and in the case of glucose, for self-testing. However, the application of biosensors in other
industrial sectors is still limited. In fact commercialization of biosensor technology has
