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T C Pearce

Publications and source records attributed to T C Pearce.

5 recordsLinked to original sources
PubMed2001

Optical multibead arrays for simple and complex odor discrimination.

A fiber optic bead-based sensor array platform has been employed to discriminate between six different odors and air carrier gas. Six different bead sensor types, with over 250 replicates of each, were monitored before, during, and after odor exposure to produce time-dependent fluorescence response patterns that were unique for each sensor-analyte combination. A total of 2,683 sensors were analyzed with respect to changes in their fluorescence, and signals from identical sensor beads were averaged to improve signal-to-noise ratios. Analyte classification rates of 100% were achieved for three complex (coffee bean) odors and three pure (simple) odors (toluene, acetone, 1,3-dinitrotoluene) measured at their highest relative concentrations. When lower odor concentrations were employed, the system exhibited better than 85% classification rates for analyte discrimination. Sensor response repeatability to these odor stimuli has also been quantified statistically, which is vital in defining the detection limit of the overall system. These results demonstrate, for the first time, the utility of our bead array technology for discriminating between different odor types at various dilution levels.

Journal Article↗
PubMed1999

Characterizing complex chemosensors: information-theoretic analysis of olfactory systems.

The mechanisms that underlie a wine lover's ability to identify a favorite vintage and a dog's ability to track the scent of a lost child are still deep mysteries. Our understanding of these olfactory phenomena is confounded by the difficulty encountered when attempting to identify the parameters that define odor stimuli, by the broad tuning and variability of neurons in the olfactory pathway,and by the distributed nature of olfactory encoding. These issues pertain to both biological systems and to newly developed 'artificial noses' that seek to mimic these natural processes. Information theory, which quantifies explicitly the extent to which the state of one system (for example, the universe of all odors) relates to the state of another (for example, the responses of an odor-sensing device),can serve as a basis for analysing both natural and engineered odor sensors. This analytical approach can be used to explore the problems of defining stimulus dimensions, assessing strategies of neuronal processing, and examining the properties of biological systems that emerge from interactions among their complex components. It can also serve to optimize the design of artificial olfactory devices for a variety of applications, which include process control, medical diagnostics and the detection of explosives.

Animals↗
PubMed1997

Computational parallels between the biological olfactory pathway and its analogue 'the electronic nose': Part II. Sensor-based machine olfaction.

Over the last fifteen years, we have witnessed a rapid expansion in the development of artificial odour sensing systems, or so called 'electronic nose' systems. Whilst the power of this approach to flavour has undoubtedly been demonstrated by its recent application to various complex odours, it will be argued that the original research programme, aimed at developing a comparative model of the biological olfactory pathway, has degenerated into an attempt to obtain an ad hoc workable system, based around readily available sensor and pattern recognition (PARC) technologies. At the time, the first 'model' nose system reflected the limited understanding of sensory information processing carried out within the biological olfactory pathway. We are now presented with an opportunity to evaluate and re-assess the architecture for an electronic nose, in view of the recent advances in understanding the key processing principals exploited by the olfactory bulb and cortex in the identification and characterisation of molecular stimuli. In Part II of this paper, we examine the parallels that exist between the biological olfactory system and the electronic nose. It is shown that the two systems share many similarities in their architectures and other properties, such as odour delivery, nonspecific sensor/receptor response, sensor/receptor preprocessing and content addressable memory (CAM) function. Of particular importance, both systems need to overcome similar operating problems, such as sensor/receptor drift, degeneration and poisoning, limited sensor/receptor sensitivity, discrimination of odour quality invariant of intensity and also the identification of particular odour components within a mixture of background odours. Finally, a number of opportunities for improving the biological plausibility of electronic nose systems are suggested that may yield an improvement in performance.

Animals↗
PubMed1997

Computational parallels between the biological olfactory pathway and its analogue 'the electronic nose': Part I. Biological olfaction.

Over the last fifteen years, we have witnessed a rapid expansion in the development of artificial odour sensing systems, or so called 'electronic nose' systems. Whilst the power of this approach to flavour analysis has undoubtedly been demonstrated by its recent application to various complex odours, it will be argued that the original research programme, aimed at developing a comparative model of the biological olfactory pathway, has degenerated into an attempt to obtain an ad hoc workable system, based around readily available sensor and pattern recognition (PARC) technologies. At the time, the first 'model' nose system reflected the limited understanding of sensory information processing carried out within the biological olfactory pathway. We are now presented with an opportunity to evaluate and re-assess the architecture for an electronic nose, in view of the recent advances in understanding the key processing principals exploited by the olfactory bulb and cortex in the identification and characterisation of molecular stimuli. In Part I of this paper, the rapid developments in the understanding of the information processing performed by the biological olfactory system are critically reviewed, and its relevance to current research in artificial olfaction is considered. Not only have the initial biochemical pathways involved in the transduction of odour stimuli been uncovered, but also computational models of the key synaptic circuits have advanced to the point where network simulations are clearly capable of odour discrimination. The key processing principles exploited in the olfactory pathway for overcoming operating constraints such as sensor drift/degeneration, limited sensitivity, and xenobiotic response are highlighted, so that their integration into the electronic analogue may be explored in Part II.

Computer Simulation↗