Biomedical application of an electronic nose

Causes and Management of Halitosis: A Narrative Review

Halitosis is defined as the presence of an unpleasant odor in exhaled air, regardless of its cause. In most patients with halitosis, the condition causes embarrassment and interferes with social interactions and daily life. Furthermore, bad breath can be a sign of an underlying disease. Understanding the factors and causes that lead to halitosis and its manifestations could facilitate proper management of this condition. To properly diagnose and treat patients, healthcare professionals, including primary care physicians and dental professionals, must be familiar with the etiology and appropriate management of the disease. Consequently, this review aims to provide practitioners with up-to-date information on the etiological factors of halitosis to facilitate the establishment of preventive measures and provide accurate diagnosis and management.

Assessment of the Indoor Odour Impact in a Naturally Ventilated Room

Indoor air quality influences people’s lives, potentially affecting their health and comfort. Nowadays, ventilation is the only technique commonly used for regulating indoor air quality. CO₂ is the reference species considered in order to calculate the air exchange rates of indoor environments. Indeed, regarding air quality, the presence of pleasant or unpleasant odours can strongly influence the environmental comfort. In this paper, a case study of indoor air quality monitoring is reported. The indoor field tests were conducted measuring both CO₂ concentration, using a photoacoustic multi-gas analyzer, and odour trends, using an electronic nose, in order to analyze and compare the information acquired. The indoor air monitoring campaign was run for a period of 20 working days into a university room. The work was focused on the determination of both CO₂ and odour emission factors (OEF) emitted by the human activity and on the evaluation of the odour impact in a naturally ventilated room. The results highlighted that an air monitoring and recycling system based only on CO₂ concentration and temperature measurements might be insufficient to ensure a good indoor air quality, whereas its performances could be improved by integrating the existing systems with an electronic nose for odour detection.

Halitosis: a review of the etiologic factors and association with systemic conditions and its management

Halitosis is a general term defined as an unpleasant or offensive odor emanating from the breath, arising from either oral or nonoral sources. Extraoral factors, such as ear-nose-throat conditions or gastrointestinal, respiratory, and systemic diseases, may also contribute to oral malodor. Although, halitosis has a multifactorial etiology, local factors play an important role in the majority of cases. Halitosis may lead to significant personal discomfort and social embarrassment. Assessment of halitosis can be performed using organoleptic measurements, sulfide monitoring, gas chromatography, microbial testing and chemical test strips. Management approaches are based on masking oral malodor, reducing the levels of volatile organic compounds (VOCs) and volatile sulfur compounds (VSCs), and mechanical and/or chemical treatment. This review aims to identify the etiology of oral halitosis, describe the methods available for assessment and differential diagnosis and introduce a variety of management strategies. The importance of a multidisciplinary approach for the improvement of overall health and for the management and prevention of halitosis is highlighted.

Sniffing out cancer using the JPL electronic nose: a pilot study of a novel approach to detection and differentiation of brain cancer

A proof-of-concept study was done to determine whether an electronic nose developed for air quality monitoring at the Jet Propulsion Laboratory (JPL) could be used to distinguish between the odors of organ and tumor tissues, with an eye to using such a device as one of several modes in multi-modal imaging and tumor differentiation during surgery.

HYPOTHESIS

We hypothesized that the JPL electronic nose (ENose) would be able to distinguish between the odors of various organ and tumor tissues.

MATERIALS AND METHODS

The odor signatures, or array response, of two organs, chicken heart and chicken liver, and cultured glioblastoma and melanoma tumor cell lines were recorded using the JPL Electronic Nose. The overall array responses were compared to determine whether they were sufficiently different to allow the organs and cell lines to be identified by their array responses.

RESULTS

The ENose was able to distinguish between the two types of organ tissue and between the two types of tumor cell lines. The variation in array response for the organ tissues was 19% and between the two types of cultured cell lines was 22%.

CONCLUSION

This study shows that it is possible to use an electronic nose to distinguish between two types of tumor cells and between two types of organ tissue. As we conducted the experiment with a sensor array built for air quality monitoring rather than for medical purposes, it may be possible to select an array that is optimized to distinguish between different types of cells and organ tissues. Further focused studies are needed to investigate the odor signatures of different cells as well as cellular proliferation, growth, differentiation and infiltration.

Body Odor Similarity in Noncohabiting Twins

There is currently considerable interest in biometric approaches using human odor as a marker of disease or genetic individuality. Body odor is also thought to be used during mate choice to select genetically compatible mates. The idea that body odor reveals information about both genetic identity and genetic similarity is most readily tested by examining odor in twin pairs. However, although this idea can be traced back 130 years to Francis Galton in 1875, most studies using dogs fail to control for shared environmental effects associated with cohabitation. Here we show that odors of identical twins (but not dizygotic twins) can be matched by human sniffers at rates better than chance, even when the twins are living apart. In addition, matching frequencies for identical twin odors were not significantly different from those for duplicate odors from the same individual. These results indicate an important genetic influence on body odor and the potential for developing technologies for human odor printing in relation to underlying genotype.

Smelling renal dysfunction via electronic nose

The human body odor plays an important role in social communication in various situations, like the olfactory identification of partners and relatives as well as in parents-child interactions. In patients with renal dysfunction the compound of sweat and volatile gases is changed because of the limited ability for removing metabolic products from the blood. The regulation of electrolyte composition and acid-base balance are also altered so that the body odor of these patients may be significantly influenced by these disorders. We show the ability of an electronic nose to detect changes in the human body odor in consequence of renal dysfunction by reducing multivariate sensor signals with principal component analysis to its first and second principal odor component (POC). All healthy subjects could clearly be distinguished from patients with renal failure using quadratic discriminant analysis, whereas a correct classification of 95.2% (98.4% using 1st-3rd POC) of patients between end stage renal failure and chronic renal failure was found. This methodology of analyzing human body odor may also provide new approaches for investigating symptoms of renal failure and for diagnosing other diseases of internal or cutaneous origin.

Clinical assessment of oral malodor by the electronic nose system

A recently developed electronic nose has not yet been clinically applied to evaluations of oral malodor. This investigation sought to determine whether an electronic nose could clinically assess oral malodor. Twenty-nine healthy adults and 49 patients were assessed by results of an actual organoleptic test, a score representing malodor strength with an electronic nose in "top-note" mode (top-note score), and measurements of volatile sulfur compound (VSC) concentrations. The correlation coefficient between top-note and actual organoleptic scores (r = 0.71) was comparable with the log VSC and actual organoleptic scores (r = 0.63). However, the area under the receiver-operating characteristic plots for top-note score was significantly larger than that for log VSC. In logistic regression analyses with top-note score as a dependent variable, probing depth, tongue coating, and plaque control record each had independent associations. Our findings suggest that the top-note score from an electronic nose examination may be useful for the clinical evaluation of oral malodor.