Active sensing electrical methods

Electric field transducers can also be used. They generate a capacitive field in a hazard area. Any grounded object in the field can he detected. Operators working in that area are grounded and can he sensed by this method to stop the machine before its activation. These are different guards and safety devices that are normally used to avoid mechanical hazards. 

The equivalent conductivity at finite dilutions is less than Aoo, not on account of incomplete dissociation but because the motion of each ion in the electric field is interfered with by the others. An approximate correspondence between AyjA and the apparent degree of dissociation determined by thermodynamic methods is fortuitous in the sense that the mechanisms underlying the reduction in activity coefficient on the one hand and the lowering of the equivalent conductivity on the other are different. Conductivity of electrolytes has lost some of the fundamental significance which it appeared to possess in the days of Arrhenius, but it remains an interesting property of one of the most important classes of solutions. 

The simplest component of an electrical circuit is a wire, and the design of molecular wires has received a great deal of attention. In a broad sense, this term can be used to designate any molecular" structme able to mediate the transfer of electrons between appropriate electron donor and acceptor sites (electrodes, photoactive, and redox-active molecular components). In practice, different "conduction mechanisms may apply, depending on the molecular structure of the wire and on the type of experimental setup used (see below). Molecular wires were studied in a variety of experimental conditions, depending on the nature of the donor and acceptor terminals the wire is connected to. and on the method used to detect the electron flow. Available methods can be broadly divided into the following (Fig. 1) photoinduced eiectron transfer in donor-wire-acceptor systems (dyads), fast electrochemistry of adsorbed wire-electroactive group assemblies, and conductance [/(V)] measurements on metal-wire-metal junctions. 

The most Important electrical phenomena in chemical sensing are electrical conductivity. Interfacial potentials (l.e., potentiometry), and electrochemical reaction currents (l.e, faradalc or amperometric methods). All depend on charge exchange and transport processes in some manner, and all have been active research areas in recent years. 

The EEG signal can be time averaged based upon synchronization pulses from the stimulator. Electrical activity and the brain s electric response can by this method be extracted from noise. In this way, hearing sense of small children and babies can be examined. 

---