Measurement of volatile organic compounds (VOCs) released from a human body holds great potential for non-invasive and convenient assessment of metabolisms or disease screening. Here, we introduce a biochemical monitoring system for external ear-derived ethanol vapor. The monitoring system consisted of an over-ear gas collection cell and a biochemical gas sensor (bio-sniffer) for ethanol. The bio-sniffer for ethanol was composed of a bifurcated optical fiber, which was connected to a UV-LED (λ = 340 nm), a photomultiplier tube, and an alcohol dehydrogenase (ADH) immobilized membrane. Gaseous ethanol was oxidized through an ADH-catalyzed reaction with the reduction of co-enzyme, β- nicotinamide adenine dinucleotide (NAD). Ethanol was finally measured by detecting the autofluorescence of a product of this reaction, a reduced form of NAD (NADH), at the wavelength of 490 nm. Characterization of the monitoring system demonstrated the high sensitivity with a broad dynamic range (26 ppb – 554 ppm), high selectivity to ethanol, and capability of continuous measurement, which allowed us to monitor external ear-derived ethanol vapor after drinking alcohol. The experiment revealed that there was little interference from sweat in sensor signals at the external ear and a similar temporal change of ethanol concentration to that of breath. These features indicate the suitability of external ears for non-invasive blood VOCs monitoring and the high degree of usefulness of the developed monitoring system.
Volatile organic compounds in exhaled breath and transdermal gas reflect biochemical information such as conditions of diseases and activities metabolisms. In the laboratories, such volatile markers were measured by large analytical systems like gas chromatography-mass spectrometry. If a sensor for volatile markers could be developed that could be used as easily as a wearable device, it could provide early screening for signs of disease and metabolic abnormalities. We have been developing optical biosensors for volatile markers based on nicotinamide adenine dinucleotide (NADH)-dependent enzymes. The NADH has a fluorescence (excitation 340 nm, emission 490 nm) and can be utilized to monitor enzyme reactions. Various kinds of volatile markers including ethanol, acetaldehyde, acetone, 2-propanol and etc could be measured by this technique. Gas imaging was also possible by employing fluorescence imaging optics. Here we introduce gas sensors and imaging systems using a bio-fluorometric technique for human volatile marker sensing.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.