Differentiation of Agaricus species and other homobasidiomycetes based on volatile production patterns using an electronic nose system

Comparisons of the qualitative volatile production patterns between seven species of Agaricus, and between two of Volvariella and Pleurotus and one Coprinus species when grown at 25°C on agar media for 14d were made. There was good reproducibility between the volatile production patterns of the same species using an electronic nose unit with a 14 conducting sensor polymer array. Principle Component Analysis (PCA) showed that it was possible to discriminate between five of the seven Agaricus species, but that some overlap occurred between the others. Cluster analysis showed that there was also overlap between some species with the tropical collection of A. bitorquis separating out from the others. The volatile production profile of the commercial A. bisporus was close to that of a wild species, A. campestris. A. bisporus could be readily differentiated from other non-Agaricus species. This study demonstrates the potential for using electronic nose systems to rapidly differentiate mycelial cultures of homobasidiomycete mushrooms

Textile-based wearable sensors for assisting sports performance

There is a need for wearable sensors to assess physiological signals and body kinematics during exercise. Such sensors need to be straightforward to use, and ideally the complete system integrated fully within a garment. This would allow wearers to monitor their progress as they undergo an exercise training programme without the need to attach external devices. This takes physiological monitoring into a more natural setting. By developing textile sensors the intelligence is integrated into a sports garment in an innocuous manner. A number of textile based sensors are presented here that have been integrated into garments for various sports applications

Discrimination of Allium headspace volatiles affected by variations in genotype growing environment and storage using an electronic noses

Alliums are valued mainly for their unique organosulphur-derived flavours and aromas. Traditional sensory and analytical determinations of Allium quality are constrained by high cost, technical difficulties and, time and human limitations. This thesis investigates the potential for use of relatively novel electronic nose (E-nose) technology for Allium discrimination. Chapters 3, 4 (Sections 4.1 to 4.3), 5 (Sections 5.1 and 5.2) and Appendices II and III inclusive have been published or submitted for publication. Consequently, Chapters in this thesis are presented in the form of papers. The E-nose AromaScan LabStation A32/8S (Osmetech Pic., UK) consists of 32 conducting polymer miniature sensors. Adsorbed odour molecules alter the electric conduction mechanism of the sensor polymer. The response is measured as proportional (%) change in sensor resistance ratio (%dR/R). The E-nose discriminated Allium types (Chapter 3), varieties of spring onion grown with or without sulphur addition and a single variety of spring onion grown under different levels of sulphur, nitrogen, water-deficit stress and soil type (Chapter 4). Bulb onion affected by nitrogen, sulphur and soil type and diced onion sealed in polyethylene bags stored at 4°C for 9 days were also discriminated by the E-nose (Chapter 5). A descriptive model for the direction of E-nose sensor polymer response to Allium headspace volatiles affected by genotypic differences and edaphic variables was outlined in Section 6.2. Principal Component Analyses (PCA) of E-nose data sets output accounted for >75% to nearly 100% of variations in the Alliums. The variations in Allium genotype differentially affected the E-nose sensor conductivity following headspace volatiles interaction with sensor polymer element. Classification of data sets output showed greater (Mahalanobis distance statistic, D² >3.0) sensitivity of spring onion cvs Guardsman and Fragrance to S fertilisation while the headspace volatiles characteristics of cvs Winter Over and Paris Silverskin were not significantly (D²3.0) and thus, increased %dR/R. Overall, N-fertilised onion cv. Sprinters reduced E-nose sensor conductivity leading to an increase in %dR/R. Increases in water-deficit stress i.e. > -0. 80 MPa soil water potential, SWP generally reduced separation between E-nose data set clusters for clay versus sandy loam soils from D² = 43.2 for -0.01 MPa SWP to D² = 6.2 for -1.19 MPa. Headspace volatiles of onions grown in the glasshouse clay increased %dR/R compared to reduced %dR/R values for both glasshouse and field sandy loam soils. The E-nose detected gradual changes in headspace volatiles of diced onion wrapped in polyethylene bags stored at 4°C for 9 days. The changes in headspace volatiles reduced %dR/R values while data set cluster separations with reference to day 0 for each sampling time increased from D² = 3.6, 5.8 and 7.0 on days 3, 6 and 9, respectively. The results suggested that Allium quality can be assessed with ease along production, postharvest and marketing chains compared to traditional destructive methods. Linear correlations for E-nose data sets versus Allium pungency determinants (pyruvic acid and lachrymatory potency), total soluble solids and dry-matter were poor. The thesis discusses the commercial significance of the result and its implication for the development of E-nose sensor tailored for Alliums. This would promote application and use of E-nose technology in the Allium industry, germplasm evaluation, and discrimination of agronomic variables and possibly, monitoring spoilage pathogens during storage. The effects of nitrogen, sulphur, water-deficit stress and soil type and their interactions have given new insight into agronomic inputs on growth and microbial load (Chapters 4.3, 5.1 and Appendix III)

Application and uses of electronic noses for clinical diagnosis on urine samples: A review

The electronic nose is able to provide useful information through the analysis of the volatile organic compounds in body fluids, such as exhaled breath, urine and blood. This paper focuses on the review of electronic nose studies and applications in the specific field of medical diagnostics based on the analysis of the gaseous headspace of human urine, in order to provide a broad overview of the state of the art and thus enhance future developments in this field. The research in this field is rather recent and still in progress, and there are several aspects that need to be investigated more into depth, not only to develop and improve specific electronic noses for different diseases, but also with the aim to discover and analyse the connections between specific diseases and the body fluids odour. Further research is needed to improve the results obtained up to now; the development of new sensors and data processing methods should lead to greater diagnostic accuracy thus making the electronic nose an effective tool for early detection of different kinds of diseases, ranging from infections to tumours or exposure to toxic agents

Design and Analysis of High-Frequency Quartz Crystal Microbalance Sensor Array with Concentric Electrodes and Dual Inverted Mesa Structure for Multiple Gas Detection

Lung Cancer is one of the most deadly diseases which claim millions of lives all around the world every year. One of the major reasons that make the treatment process of lung cancer hard is that the patients are diagnosed only during the later stages. Lung cancer patients exhales volatile organic compounds in their breath in low concentration even during the early stages of the disease. There are many gas sensors available to detect these volatiles. However, there are certain disadvantages which make most of the conventional gas sensors unsuitable for early detection. Quartz crystal microbalance (QCM) is one of the promising candidates for volatile organic compounds detection. This thesis describes the design and analysis of the high-frequency quartz crystal microbalance sensor array with a novel concentric electrode and dual inverted mesa structure. Conventional QCM sensors are limited with circular electrodes and single channel design which limits the sensing ability. The proposed QCM sensor array has advantages of a uniform displacement profile with the concentric electrodes and multiple channels on a high frequency monolithic quartz substrate without interference with the dual inverted mesa design. This high frequency multiple channels make the multiple gas detection feasible. Therefore, in this thesis the critical design parameters of this proposed design are analyzed and optimized through a comprehensive finite element analysis in COMSOL Multiphysics and analytical modelling. In addition, the interference between multiple QCM channels has been further eliminated. Furthermore, the fabrication procedure for the proposed high frequency QCM gas sensor array has been proposed and analyzed

Ammonia Gas Detection by Tannic Acid Functionalized and Reduced Graphene Oxide at Room Temperature

Reduced graphene oxide (rGO) based chemiresistor gas sensor has received much attention in gas sensing for high sensitivity, room temperature operation, and reversible. Here, for the first time, we present a promising chemiresistor for ammonia gas detection based on tannic acid (TA) functionalized and reduced graphene oxide (rGOTA functionalized). Green reductant of TA plays a major role in both reducing process and enhancing the gas sensing properties of rGOTA functionalized. Our results show rGOTA functionalized only selective to ammonia with excellent respond, recovery, respond time, and recovery times. rGOTA functionalized electrical resistance decreases upon exposure to NH3 where we postulated that it is due to n-doping by TA and charge transfer between rGOTA functionalized and NH3 through hydrogen bonding. Furthermore, rGOTA functionalized hinders the needs for stimulus for both recovery and respond. The combination of greener sensing material and simplicity in overall sensor design provides a new sight for green reductant approach of rGO based chemiresistor gas sensor

Parameter identification and simulation of conducting polymer micro-sensors using global spectral projection methods

Chemical micro-sensors have the potential of a wide range ofapplications that include odor sensing in food industry, environmentalmonitoring, improvedprocess control, detection of hazardous chemicals, medicaldiagnosis, and control of automobile emissions. In this thesis,a model is developed describing the electrical response of a thin-film, conducting polymer sensor to an air mixture containing different target gas species. Numerical methods for discretizing the initial-boundary value problem defining the film conductance model are presented. Nonlinear parameter identification methods are used to identify a subset of the model parameters.Two models of sensor operation are studied. In the first case, the isothermal response of the sensor to time varying gas phase concentration is considered. The effectiveness of sensor cleaning is studied in the second case in which the sensor substrate temperature is periodically increased to drive out adsorbed gas species. Good agreement is found when model predictions are compared with published experimental results

Airborne chemical sensing with mobile robots

Airborne chemical sensing with mobile robots has been an active research areasince the beginning of the 1990s. This article presents a review of research work in this field,including gas distribution mapping, trail guidance, and the different subtasks of gas sourcelocalisation. Due to the difficulty of modelling gas distribution in a real world environmentwith currently available simulation techniques, we focus largely on experimental work and donot consider publications that are purely based on simulations

Dynamic Temperature Modulation Sensing Technique of Electronic Nose: A Review

Electronic nose (E-nose) is a simulation of human nose, which consists of a gas sensor array and an artificial intelligent algorithm. The gas sensing properties of semiconductor sensors are affected by the heating temperature. For most gases, there exists the optimum oxidation temperature. If sensor response is recorded, we can obtain the data with abundant information at different working temperatures. The selectivity and sensitivity of a gas sensor array are the bottleneck of its development. Dynamic temperature modulation sensing technique is a use of semiconductor sensor temperature modulation characteristics by modulating its heating voltage to realize the heating temperature in a range of changes, people can record the corresponding response. The temperature modulation sensing technique can effectively improve the sensitivity of E-nose and realize the detection of low concentration gas, so it is of great practical significance to development technique of E-nose, which is based on temperature modulated sensing system for promoting the detection speed. But so far, the technique is only used for the detection of several common gases (such as methanol, ethanol, carbon monoxide, et al). The aim of this review is to supply a summary of the development and significant achievements of dynamic temperature modulation sensing technique used in E-nose in recent years. We are also looking forward to seeing dynamic temperature modulation sensing technique to accomplish more breakthroughs and get more achievements