Applications of Machine Olfaction - The Electronic Nose Artificial Olfaction Technology - page 230

the sensor type, relative humidity, and gas concentration/temperature conditions.
The sensor signal conditioning test period is long. The main thing is sensitivity of
sensor for NO detection which varies as different types of sensors available in the
market are the same, so as per application definition the sensor type can be
selected and accordingly the price of the sensor varies. Sensor requires a low noise
potentiostat circuit for lowest noise and best resolution (i.e., NOB4).

8.2 Case Study 2: Practical Approach to Detect Alcohol
in Human Breath

8.2.1 The Problem

Most frequently mentioned observation of traffic police officers in alcohol-related
traffic offences is alcohol breath odor. The odor frequency is categorized as slight,
moderate, or strong.
An organic compound containing carbon and hydrogen atoms and a hydroxyl
(-OH) group is identified as alcohol. Alcohols are infinitely soluble in water, weak
acids, and are clear and colorless. Alcohols are of various types and all have their
own properties and toxicities and as such death will result if a sufficient quantity is
consumed or else introduced into the body. Table 8.11 shows the various types of
alcohols and their properties [ 48 ].
Detection of alcohol concentration in the brain is essential for safety on the road
as well as in the workplace. Suitably, blood alcohol concentration (BAC), defined
as the percentage of alcohol in the blood, is used to assess the alcohol level in the
brain tissue as a measure of impairment from alcohol poisoning.
Most people show measurable mental mutilation at about 0.05 % BAC. Above
this level, the capability to operate an automobile deteriorates gradually with
increased blood alcohol level. For the average person, an unconsciousness

Table 8.11 Types of alcohols

Name Formula Boiling

point (C)

Uses Toxicity and

metabolites

Methanol methyl alcohol
wood alcohol

CH 3 OH 64.5 Denaturant solvent

paint remover fuel

*75 ml
Formaldehyde

Ethanol ethyl alcohol grain
alcohol

C 2 H 5 OH 78.3 Beverage solvent *400-500 ml

Acetaldehyde

medicinal Veh. fuel

Isopropanol isopropyl
alcohol rubbing alcohol

C 3 H 7 OH 82.3 Denaturant antiseptic *250 ml

Acetone

Butanol butyl alcohol C 4 H 9 OH 117 Perfume and aftershave

Base

*100 ml