Artificial Nose Research Articles

Sensing applications of synthetic transport systems

This feature article offers a comprehensive account of a decade of research devoted to the combination of the grand sensing principles with synthetic transport systems that act in lipid bilayers. Differential sensing, that is pattern generation and pattern recognition, is exemplified with an artificial nose. The aptamer version of immunosensing is realized with sticky-end polymers of DNA double helices for both signal generation and signal transduction. Biosensing, that is the use of enzymes for signal generation, is exemplified first with an artificial tongue and then expanded to analytes such as cholesterol, phytate or polyphenols. Enjoyable also for the general reader, we hope that this account will inspire supramolecular organic as well as analytical, physical and biological chemists.

Colorimetric Artificial Nose for Monitoring Traditional Solid State Fermentation Process of Vinegar Pei

Colorimetric Artificial Nose for Monitoring Traditional Solid State Fermentation Process of Vinegar Pei

Application of artificial nose in CCU patients with tracheal intubation

Objective To explore the application efficacy of artificial nose in CCU patients with tracheal intubation.Methods Totals of 62 patients with tracheal intubation were randomly divided into the group of artificial nose and group of electrothermal and constant temperature moist,then the sputum viscosity,irritating cough,airway administration hours,average intubation time,consumables costs,and the incidence of ventilator-associated pneumonia in two groups were observed and compared.Results In artificial nose group,the incidence of irritating cough was28.1％,the incidence of ventilator-associated pneumonia was 15.6％,airway administration hours was( 2.3 ± 0.5 ) h,average intubation time was ( 112 ± 6.5 ) h,consumables costs was (44.2±6.7)yuan all better than that of electrothermal and constant temperature moist group,which was 71.9％,37.5％,( 3.5 ± 0.6 ) h,( 133 ± 7.8 ) h,and ( 56.3 ± 1.5 ) yuan,respectively,differences were statistically significant ( x2 =12.25,3.925 0; t =8.660 5,11.699 8,8.212 9,respectively; P ＜ 0.01 or P ＜0.05).Sputum viscosity status of artificial nose group was that Ⅰ grade 12.5％,Ⅱ grade 62.5％,Ⅲ grade 25.0％,whilethat of electrothermal and constant temperature moist group was 46.9％,25.0％,28.1％,respectively,and the differences was statistically significant ( x2 =11.559 0,P ＜ 0.01 ).Conclusions Artificial nose using in patients with endotracheal intubation can achieve the desired efficacy of airway humidification,improve the efficacy of airway administration,save energy and time and significantly reduce the incidence of ventilator-associated pneumonia,which likely to be generally used in clinical. Key words: Artificial nose; Airway humidifying; Nursing management; CCU

Colorimetric artificial nose for baijiu identification

ABSTRACTBased on a colorimetric sensor array, five commercial baijiu were analysed by a simple colorimetric artificial nose. Utilizing porphyrin, porphyrin derivatives and chemically responsive dyes as sensitive materials, the sensor array of the artificial nose showed a unique pattern of colorific changes upon its exposure to baijiu. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to investigate the presence of classes inside the sample and linear discriminant analysis (LDA) was employed to identify baijiu of different fragrances. The results of PCA and HCA analyses suggested that the colorimetric artificial nose might characterize the types of baijiu according to their trace components, rather than the raw materials, fermentation method, manufacturing process and other conditions. The accuracy in terms of the classification of each baijiu flavours using LDA was 100% and confirmed the great potential of colorimetric artificial nose in the detection of baijiu flavour styles. Copyright © 2012 John Wiley & Sons, Ltd.

Colorimetric Artificial Nose and Pattern Recognition Methods for the Concentration Analysis of NH3

An investigation was made to evaluate the capacity of a colorimetric artificial nose to detect toxic gas at low concentration. A low-cost and simple colorimetric sensor array for identification and quantification of NH3 with different concentrations (30, 90, 150, and 210 ppb) were reported. Using porphyrin, porphyrin derivatives (mainly metalloporphyrins), and chemically responsive dyes as the sensing elements, the developed sensor array of artificial nose showed a unique pattern of colorific change upon its exposure to NH3 with different concentrations. The dynamic responses of colorimetric sensor array to NH3 and colorimetric sensor array to various NH3 concentrations at the same time point showed that there was a positive relationship between the color change values of spots and contractions of NH3. NH3 with four concentrations were measured, and the response values at six different collection times were conducted by linear discrimination analysis (LDA) and artificial neural network (ANN). The four concentrations were discriminated completely by LDA. The response value of the colorimetric artificial nose at 0.4 min was optimum for discrimination. The method of ANN was performed and less than 5% of error by using T-S fuzzy neural network.

Characterization of a clinical olfactory test with an artificial nose

Clinical olfactory tests are used to address hyposmia/anosmia levels in patients with different types of olfactory impairments. Typically, a given test is employed clinically and then replaced by a new one after a certain period of use which can range from days to several months. There is a need to assess control quality of these tests and also for a procedure to quantify their degradation over time. In this paper we propose a protocol to employ low-cost artificial noses for the quantitative characterization of olfactory tests used in clinical studies. In particular, we discuss a preliminary study on the Connecticut Chemosensorial Clinical Research Center Test kit which shows that some odorants, as sensed by an artificial nose, seem to degrade while others are potentiated as the test ages. We also discuss the need to establish a map of correspondence between human and machine olfaction when artificial noses are used to characterize or compare human smell performance in research and clinical studies.

Direct measurement of extracellular electrical signals from mammalian olfactory sensory neurons in planar triode devices

An artificial nose was developed to mimic aspects of sensory transduction of the peripheral mammalian olfactory system. We directly cultured and differentiated rat olfactory sensory neurons (OSNs) on indium-tin oxide electrodes of planar triode substrates without a coupling agent. Direct voltage (~50 μV) and current (~250 nA) signals were measured simultaneously when OSNs on the planar triode substrates were exposed to odorant mixtures. The response signals were sensitive to the concentration of the odorant mixture, with a typical lifetime, shape, and adaptation profile as seen in responses upon repeated stimulation in vivo. We found that the rising time to the peak current was ~161 ms, while the signal back to baseline was in 1.8 s, which are in agreement with the natural intracellular electrophysiological responses. These results provide the first evidence that mature OSNs grown in a planar triode device are able to detect direct electrophysiological responses to odorants.

Mimicking the human smell sensing mechanism with an artificial nose platform

Sensing smell is a highly complex biological process, and characterizing and mimicking the interaction between the olfactory receptor (OR) protein and its ligands is extremely challenging. Herein, we report a highly sensitive and selective human nose-like nanobioelectronic nose (nbe-nose), which responds to gaseous odorants sensitively and selectively, has a signal specificity pattern similar to that in the cellular signal transduction pathway, and maintains an antagonistic behavior similar to the human nose. The human olfaction mechanism was mimicked by using carboxylated polypyrrole nanotubes (CPNTs) functionalized with human OR protein. The nbe-nose was able to detect gaseous odorants at a concentration as low as 0.02 parts-per-trillion (ppt), which was comparable to a highly trained, human expert’s nose. The nbe-nose can be used scientifically for smell mechanism studies. It can be also applied to various fields that rely on smell monitoring for industrial and public purposes.

An Artificial Nose Based on M-Porphyrin (M = Mg, Zn) Thin Film and Optical Spectroscopy

Artificial nose has recently become an emerging instrument for quality assurance in the food industry. These paper present the optical gas sensors based on Magnesium-5, 10, 15, 20-tetra phenyl-porphyrin (MgTPP) and Zinc-5, 10, 15, 20-tetra phenyl-porphyrin (ZnTPP) thin films and their application as an artificial nose. Based on the measurement of optical absorbance response using a general UV-Vis spectroscopy, this artificial nose was tested to discriminate various volatile organic compounds (VOCs) and Thai beverages. Atomic force microscopy (AFM) and X-rays diffraction (XRD) were used to confirm the polycrystalline structure of the sensing materials. Density functional theory (DFT) calculations reveal that MgTPP interacts more strongly with the VOCs than ZnTPP, especially with methanol. The classification results of VOCs and Thai beverage vapors using the principal component analysis indicate that both MgTPP and ZnTPP-based artificial noses can be an efficient tool for quality assurance of alcoholic beverages.

Invited Review Article: An odor-sensing system—powerful technique for foodstuff studies

This work examines gas sensor array technology combined with multivariate data processing methods and demonstrates a promising potential for rapid, non-destructive analysis of food. Main attention is focused on detailed description of sensor used in e-nose instruments, construction, and principle of operation of these systems. Moreover, this paper briefly reviews the progress in the field of artificial olfaction and future trends in electronic nose technology, namely, e-nose based on mass spectrometry. Further discussion concerns a comparison of artificial nose with gas chromatography-olfactometry and the application of e-nose instruments in different areas of food industry.

Colorimetric artificial nose for identification of Chinese liquor with different geographic origins

Colorimetric artificial nose was used to characterize and identify Chinese liquors from six different geographic origins. Using chemical dyes as the sensing elements, the developed colorimetric artificial nose showed a unique pattern of color changes upon its exposure to Chinese liquors. Data analysis was performed by chemometric techniques: Hierarchical cluster analysis (HCA), principal component analysis (PCA) and linear discriminant analysis (LDA). Each category of Chinese liquor could cluster together in PCA score plot. No errors in classification by HCA were observed in 45 trials. LDA model showed a 100% of prediction ability for Chinese liquor. The results demonstrated that colorimetric artificial nose was able to classify Chinese liquors from different geographic origins.

Peptide receptor-based selective dinitrotoluene detection using a microcantilever sensor

We reported that peptide could be utilized as receptor molecule in the gas phase for application in micro/nano sensors by using a specific peptide that recognizes 2,4-dinitrotoluene at room temperature and in an atmospheric environment and measuring changes in the resonant frequency of the peptide immobilized microcantilevers. By using these peptides as receptors on a microcantilever sensor, we were able to experimentally detect 2,4-dinitrotoluene (DNT) vapor at concentrations as low as parts per billion (ppb) in the gas phase. While resonant frequency changes after binding between 2,4-DNT and the specific peptide receptor that was immobilized on microcantilevers were observed, the resonant frequency of DNT nonspecific peptide immobilized microcantilever did not change when exposed to 2,4-DNT vapor. The limit of detection (LOD) was calculated to be 431 ppt of limit of detection is numerically expected by experimental based on an equation that describes the relationship between the noise-equivalent analyte concentration. These results indicate that the peptide receptors hold great promise for use in the development of an artificial olfactory system and electronic nose based on micro/nanotechnology for monitoring various chemical vapors in the gas phase such as explosive mixtures of chemicals and/or volatile organic compounds.

Plasmophore sensitized imaging of ammonia release from biological tissues using optodes

A plasmophore sensitized optode was developed for imaging ammonia (NH 3) concentrations in muscle tissues. The developed ammonia sensor and an equivalent non plasmophore version of the sensor were tested side by side to compare their limit of detection, dynamic range, reversibility and overall imaging quality. Bio-degradation patterns of ammonia release from lean porcine skeletal muscle were studied over a period of 11 days. We demonstrate that ammonia concentrations ranging from 10 nM can be quantified reversibly with an optical resolution of 127 μm in a sample area of 25 mm × 35 mm. The plasmophore ammonia optode showed improved reversibility, less false pixels and a 2 nM ammonia detection limit compared to 200 nM for the non-plasmophore sensor. Main principles of the sensing mechanism include ammonia transfer over a gas permeable film, ammonia protonation, nonactin facilitated merocyanine-ammonium coextraction and plasmophore enhancement. The vast signal improvement is suggested to rely on solvatochroism, nanoparticle scattering and plasmonic interactions that are utilized constructively in a fluorescence ratio. In addition to fundamental medicinal and biological research applications in tissue physiology, reversible ammonia quantification will be possible for a majority of demanding imaging and non imaging applications such as monitoring of low ammonia background concentrations in air and non-invasive medicinal diagnosis through medical breath or saliva analysis. The nanoparticle doped sensor constitutes a highly competitive technique for ammonia sensing in complex matrixes and the general sensing scheme offers new possibilities for the development of artificial optical noses and tongues.

Artificial Noses

The mammalian olfactory system is able to detect many more odorants than the number of receptors it has by utilizing cross-reactive odorant receptors that generate unique response patterns for each odorant. Mimicking the mammalian system, artificial noses combine cross-reactive sensor arrays with pattern recognition algorithms to create robust odor-discrimination systems. The first artificial nose reported in 1982 utilized a tin-oxide sensor array. Since then, however, a wide range of sensor technologies have been developed and commercialized. This review highlights the most commonly employed sensor types in artificial noses: electrical, gravimetric, and optical sensors. The applications of nose systems are also reviewed, covering areas such as food and beverage quality control, chemical warfare agent detection, and medical diagnostics. A brief discussion of future trends for the technology is also provided.

Identification and Quantification of Organic Vapors by Time-Resolved Diffusion in Stacked Mesoporous Photonic Crystals

Microsensors for gas-phase analytes are fundamentally limited by their inability to discriminate between analytes. While cross-reactive arrays consisting of multiple different sensor elements provide one means to identify individual analytes, these "artificial nose" devices rely on complicated data processing algorithms and they generally suffer from significant zero-point drift. Herein, we present a single component optical sensor that is capable of identifying chemical compounds at parts-per-million concentrations. The device consists of a stack of three mesoporous silicon-based photonic crystals; a porous "drift tube" is sandwiched between two optically responsive layers. The drift layer temporally separates the optical responses of the other layers, and this difference is shown to be characteristic of the analyte.

Diagnosis of head-and-neck cancer from exhaled breath

Background:Head-and-neck cancer (HNC) is the eighth most common malignancy worldwide. It is often diagnosed late due to a lack of screening methods and overall cure is achieved in <50% of patients. Head-and-neck cancer sufferers often develop a second primary tumour that can affect the entire aero-digestive tract, mostly HNC or lung cancer (LC), making lifelong follow-up necessary.Methods:Alveolar breath was collected from 87 volunteers (HNC and LC patients and healthy controls) in a cross-sectional clinical trial. The discriminative power of a tailor-made Nanoscale Artificial Nose (NA-NOSE) based on an array of five gold nanoparticle sensors was tested, using 62 breath samples. The NA-NOSE signals were analysed to detect statistically significant differences between the sub-populations using (i) principal component analysis with ANOVA and Student's t-test and (ii) support vector machines and cross-validation. The identification of NA-NOSE patterns was supported by comparative analysis of the chemical composition of the breath through gas chromatography in conjunction with mass spectrometry (GC–MS), using 40 breath samples.Results:The NA-NOSE could clearly distinguish between (i) HNC patients and healthy controls, (ii) LC patients and healthy controls, and (iii) HNC and LC patients. The GC–MS analysis showed statistically significant differences in the chemical composition of the breath of the three groups.Conclusion:The presented results could lead to the development of a cost-effective, fast, and reliable method for the differential diagnosis of HNC that is based on breath testing with an NA-NOSE, with a future potential as screening tool.

Humidificación del aire inspirado y oxigenoterapia crónica domiciliaria

The use of humidifiers in the home is a common practice in patients receiving domiciliary oxygen therapy, probably due to its extensive use in the hospital setting. However, the available evidence and clinical guidelines recommend that the use of a humidifier is not necessary in the hospital or at home when nasal prong oxygen therapy is used with a flow of oxygen of less than 4 l/min. Its generalized use, besides meaning an added cost, may entail health risks (bacterial contamination) and favor O2 escapes. On the contrary, in patients with artificial airway (tracheostomy) or when higher O2 flows are used, a humidifier device should be used (simple, thermal or artificial nose).

Effect of continuous heated humidification on artificial airway

Objective To investigate the effect of continuous heated humidification on critical patients with artificial airway. Methods 60 patients with artificial airway were randomly divided into experimental group and control group, 30 cases each group. Experimental group received continuous heated humidification and control group used artificial nose to humidify airway. To compare sputum viscidity, sputum scab, amyctic cough, respiration mucosa bleeding of two groups. Results There were significant differences between the two groups in sputum viscidity, sputum scab, amyctic cough, respiration mucosa bleeding (P ＜ 0. 05). Conclusions Continuous heated humidification can bring much better effects to patients than hygroscopic condenser humidifier. Key words: Artificial airway; Continuous heated humidification; Hygroscopic condenser humidifier

Comparison between classical and innovative class-modelling techniques for the characterisation of a PDO olive oil

An authentication study of the Italian PDO (protected designation of origin) olive oil Chianti Classico, based on near-infrared and UV-Visible spectroscopy, an artificial nose and an artificial tongue, with a set of samples representative of the whole Chianti Classico production and a considerable number of samples from a close production area (Maremma) was performed. The non-specific signals provided by the four fingerprinting analytical techniques, after a proper pre-processing, were used for building class models for Chianti Classico oils. The outcomes of classical class-modelling techniques like soft independent modelling of class analogy and quadratic discriminant analysis-unequal dispersed classes were compared with those of two techniques recently introduced into Chemometrics: multivariate range modelling and CAIMAN analogues modelling methods.

Towards an omnipotent “Artificial Nose”: detection and identification of alkylating agents using an optical sensor array

AbstractAlkylating agents are reactive, often simple, molecules that are frequently used in diverse fields such as medicine, agriculture, and organic synthesis. For over a century, some highly reactive alkylating agents are also being used as blister chemical warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and often simple structure. Here we report on a new approach for the detection and identification of such alkylating agents using a simple luminescence based array sensor that mimics the olfactory system. In order to demonstrate the potential of the approach, seven π‐conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1‐7, were adsorbed onto a solid support and exposed to vapors of alkylators 8‐15. Applying principal component analysis to the alkylation induced color shift patterns of the seven‐spot array results with a clear discrimination of the different alkylators. The comparison of the data obtained from the sensor array with known response patterns allows the clear identification of the specific alkylator. The spots are sensitive to minute concentrations of alkylators and since the detection is based on the formation of new covalent bonds these spots saturate, within seconds even at about 50 ppb. Copyright © 2010 John Wiley &amp; Sons, Ltd.