Due to the application of wireless miniature sensing systems (biosensors), the production of wearable biosensors is rapidly increasing. These wearable biosensor have been designed by exploiting the current knowledge of biotechnology and biological systems. They allow the fine monitoring of the physiological signals sent by the human body. They also utilize the knowledge of applied electronics. They are extensively being used for the diagnosis of disease in the patients. The patient's current medical conditions are recorded within the biosensor for further treatment of the disease or a particular symptom.

The main wearable biosensors are the ring biosensor and smart shirt. Both are wearable in nature and can be worn out in situations they aren't required. The first one being, the ring sensor is used to monitor oxygen concentration and heart rate in a particular person. It is basically consisting of low power power transceiver and has the ability to accomplish bi-directional communication with a base station. It also serves as a pulse oximetry sensor. Its working is based mainly on the principle of optical biosensors which are based on the phenomenon of surface plasmon resonance (SPR). In the phenomenon of SPR, a thin layer of gold on a high refractive index glass surface happens to absorb laser light leading to production of electron waves on the gold surface which occurs only at a specific angle and wavelength of incident light. These electron waves are also known as surface plasmons. This occurrence of emission of surface plasmons is extremely dependent on the surface of the gold. The surface of the gold should be in a way that the binding of a target analyte to a receptor on the gold surface leads to production of a measurable signal. The optical biosensors are of two types: Colorimetric for color change detection that measure change in light adsorption and Photometric for light intensity change detection in which photomultiplier tubes or photo-diode systems are utilized for detection of photon output for a fluorescent process or a luminescent process.

The ring biosensor uses a CR2032 and a Atmel ATmega 128L omega processor. It is easy to wear and use and does a continuous monitoring thus canceling out the complexities that are commonly experienced while using such equipment. On the other hand, its disadvantages are also there that include its high initial cost and limited number of parameters that could be detected by it.

Its working, as stated before, is based on principle of photometric optical biosensors. Since the blood volume changes with the contractions and expansion of heart muscles, it detects these changes in blood volume by photoelectric methods. LED component generates a light then which is passed to the photoresistor which then generates a voltage. Since the optical density of blood is directly proportional to the volume of blood, an increase in blood volume causes an increase in optical density, which leads to a decrease in the light emission through finger and ultimately in the increased resistance of the photo resistor.

In smart-shirts, integrated sensors and conductive fiber grid are attached to a shirt that has a shirt band connector. The shirt band connector when detects any parameters sends signals to either a PDA with Bluetooth assistance or a personal controller wireless system that carries out the further process of treatment.

These wearable biosensors have wide usages as during the times of catastrophic detection for instance monitoring of patients during risky operations, under chronic medical conditions e.g., monitoring the hypertension in cardiovascular disease and chronic surveillance of abnormal heart failure. Although they provide continuous monitoring of the body systems, their cost is very high and battery life is also usually low. It is expected that in a few years, improved biosensors with more battery life and less expensive nature that are affordable would be designed so that everyone can have an easy access to these mobile healthcare systems leading to a better healthcare facilitation and better life.

As a conclusive remark, the wearable biosensors like the ring sensor and smart shirt are significantly effective, comfortable and miniature mobile infrasture that provides information by the application of telemedicine and information technology. The use of these wearable biosensors brings a quote to my line, 'Mobile healthcare: Affordable, Anywhere, Anyone & Anytime'.

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A Budding biotechnologist + writer from India.. Visit http://in.linkedin.com/pub/shivani-sharma/4b/91b/384 or refer cv.napping@gmail.com for more details.
Researcher ID- J-4200-2012