The bio-interfaces are widening the notions of complexity, affectiveness, and naturalness to an organic scale, in which the physiological information of the users acts as data to configure an interaction that responds to their emotional state in order to match the state of their body at that particular moment. In this context, the chapter discusses the role of the bio-interfaces in building a differentiated condition of interaction governed by the biology of the users. For this, the chapter presents applications of bio-interfaces in the areas of design, art, and games, considering their use as wearable devices that provide an organic interaction between man and machine, which could, in turn, lead these systems to a co-evolutionary relationship.
TopBio-Interfaces Background
For several years, electrophysiological and electroencephalographic activities, and other measures of brain functions, have been considered means to new non-muscular channels of communication for sending messages and commands to the external world. This possibility becomes reality with the development and application of functional biometric interfaces and brain-computer interfaces (BCI) responsible for actually enabling this communication process between human-machine or human-machine-human, through the acquisition and encryption of the user's biological information. In this section, we will address the main aspects related to this context, to provide an ample understanding of the operation spectrum for both interfaces.
Functional biometric interfaces, based on checking ANS (autonomous nervous system) variability, provide information about the physical state or the behavior of those who use them, continuously gathering physiological data, that is, without interrupting user activity. For such, biosensors are used as input channels for a functional biometry system, such as: galvanic skin response sensor (GSR); blood volume pulse sensor (BVPS); breathing sensor (BS); and electromyogram sensor (EMG).
Galvanic Skin Response Sensor (GSR)
The GSR enables the possibility of measuring the parameters of electrical conductance from skin tissue through the application of two electrodes. This conductance is considered a function of the sweat gland activity, which is a part controlled by the sympathetic nervous system. Thus, when an individual suffers from anxiety or is frightened, a quick increase in skin conductance occurs due to the increase in sweat gland activity. This increase actually reflects the changes that are occurring at the stimulation level of the user’s sympathetic nervous system as the result of an internal or external stimulus. The GSR then interprets these alterations and later they may be encrypted as actions in the environment external to the user’s body, for example, the light of an environment that turns on after an increase in skin conductivity has been detected as a result of the person’s apprehension in entering a dark room. It is important to underscore that an individual's skin conductance baseline is unique and it varies as a result of many parameters, such as: gender, food diet, skin type, social context, among others.