Electronic Noses for Healthcare Applications

Breath analysis allows for monitoring the metabolic processes that occur in human
body in a non-invasive way. Comparing with other traditional methods
such as blood test, breath analysis is harmless to not only the subjects but also
the personnel who collect the samples.
However, despite its great potential, only few breath tests are commonly used in clinical
practice nowadays. Breath analysis has not gained a wider use yet. One of the main
reasons is related to standard instrumentation for gas analysis. Standard instrumentation,
such as gas chromatography, is expensive and time consuming. Its use, as well as
the interpretation of the results, often requires specialized personnel. E-nose systems,
based on gas sensor array, are easier to use and able to analyze gases in real time, but,
although cheaper than a gas chromatograph, their cost remains high.
During our research activity, we designed and developed the so called Wize Sniffer (WS), a device able
to accurately analyze human breath composition and, at the same time, to overcome the
limitations of existing instrumentation for gas analysis.
The idea of the Wize Sniffer was born in the framework of SEMEiotic Oriented Technology
for Individual’s CardiOmetabolic risk self-assessmeNt and Self-monitoring (SEMEOTICONS,
www.semeoticons.eu) European Project, and it was designed for detecting,
in human breath, those molecules related to the noxious habits for cardio-metabolic
risk. The clinical assumption behind the Wize Sniffer lied in the fact that harmful habits
such as alcohol consumption, smoking, unhealthy diet cause a variation in the concentration
of a set of molecules (among which carbon monoxide, ethanol, hydrogen,
hydrogen sulfide) in the exhaled breath. Therefore, the goal was to realize a portable
and easy-to-use device, based on cheap electronics, to be used by anybody at their
home.
The main contributions of the work were the following:
design and development of a portable, low cost, customizable, easy to use device,
able to be used in whichever context of use: we succeeded in this with using cheap
commercial discrete gas sensors and an Arduino board; 
development of a method to analyze breath composition and understand individual’s
cardio-metabolic risk; we also validated it with success on real people.
Given such good outcomes, we wanted the Wize Sniffer took a further step forward,
towards the diagnosis in particular. The application field regarded the chronic liver
impairment, as the studies which involve e-nose systems in the identification of liver
disease are still few. In addition, the diagnosis of liver impairment often requires very
invasive clinical test (biopsy, for instance).
In this proof-of-concept study, the Wize Sniffer showed good diagnosis-oriented properties
in discriminating the severity of liver disease (absence of disease, chronic liver
disease, cirrhosis, hepatic encephalopathy) on the base of the detected ammonia.