Wearable ElectroCardiogram (ECG) sensors are also
used for short-time assessment of cardiovascular diseases,
especially for people with chronic heart problems. The
ECG signal provides very useful information about the rate
and regularity of the heart beats, which are used in diagnosis
of cardiac diseases. A low power high resolution Thoracic
Impedance Variance and ECG monitoring has been developed
and incorporated in a compact plaster sensor form for wearable
low cost cardiac healthcare [33]. An asynchronous analogto-
information conversion system has been introduced for
measuring the RR intervals of the ECG signals [34]. The
system contains a modified level-crossing analog-to-digital
converter and a novel algorithm for detecting the R-peaks
from the level-crossing sampled data in a compressed volume
of data [34].
The above sensors are the most commonly used sensors
for activity monitoring of humans. There may be many other
sensors employed depending on special requirement or critical
needs. A flexible, textile capacitive sensor fabricated from
conductive textile patches to measure capacitance of the
human body has been reported [35] which could reveal
information of human activities such as including heart rate
and breathing rate monitoring, hand gesture recognition,
swallowing monitoring, and gait analysis. An amperometric
sensor composed of a multiwall carbon nanotube (MWNT)
functionalized nylon-6 mat to quantify the amount of sodium ions in sweat in real-time has been designed and
developed [36]. Wearable micromachined sensors can be very
powerful in providing accurate biomechanical analysis under
ambulatory conditions [37]. The possibility of development
of wearable skins that can monitor, sense, and interact with
the world around us in a perpetual way, thus significantly
enhancing ambient intelligence and quality of life has been
discussed [38]. It is expected that the potential applications
of wearable technologies will include the early diagnosis of
diseases such as congestive heart failure, the prevention of
chronic conditions such as diabetes, improved clinical management
of neurodegenerative conditions such as Parkinson’s
disease, and the ability to promptly respond to emergency
situations such as seizures in patients with epilepsy and cardiac
arrest in subjects undergoing cardiovascular monitoring