All devices of the medical information set are divided into 2 groups: electrodes and automotive sensors (transformers). Electrodes are used for the set of the electrical signal, which is really in the man's organism.
Automotive sensors are devices of set, which react to the impact of the measured amount with its sensitive element and also transform this impact into the handy form for the following processing. The electrodes for the taking off heart biopotential are called electrocardiographic ones (ECF). They performed the role of the contact with a body surface to complete the electrical circuit between the generator of the biopotentials and the meter. Automotive sensors are used in medical applications to analyze oxygen. Automotive sensors analysis of pacemaker's signals in the cardio monitor makes the strict requirements to the taking off device - electrodes (ECF). The reliability of analysis result depends on the quality of electrodes and hence the level of instrument complexity for signal detection against a background of interferences. The low quality of taking off can't compensate practically for technical resolutions.
The requirements applied to ECF electrodes meet the main requirements of any transformers of bioelectrical signals:
- accuracy of signal perception (minimal loses of health-giving signal in the electrodes passage;
- skin and preservation of frequency signal characteristics);
- identity of electrical and structural parameters (interchangeability, possibility of compensation of electrical parameters);
- stability in the time of transformation function (stability of electrical parameters);
- low level of sounds;
- little impact of electrode characteristics on the meter.
Echocardiography is the method of the study of heart structure and movement with the reflected ultrasound.
Phonocardiography represents the method of graphical registration of sound processes, originated as the result of cardiac performance. Phonocardiograph is a device recorded the heart sound processes. Any phonocardiograph consists of microphone, electronic amplifier, frequency filters and recorded device. The microphone converts the sound energy into the electrical signals. It must have a maximal sensitivity and it doesn't cause the distortions in the transmitted signals and it is little sensitive to the external sounds. With the method of sound energy conversion the microphones are divided into piezoelectric and dynamic.
Nowadays, dynamic microphones are often used. Their principal bases on the electromagnetic induction.
The electrical signal moves to the amplifier. Its task is to amplify the poor high-frequency vibrations, appropriated to heart noise and at least low-frequency, appropriated to the heart sounds. So, every spectrum breaks up into the ranges of low, medium and high frequencies. Necessary intensification is provided in each of these ranges. The recorded systems are used for the registration of the provided signals, which have short inertia (optical or antipitch).
Pressure sensors of the company Motorola are used in the medical institutions in many countries. They take pressure using little electrical energy.