Measurement System Of Local Bioimpedance Analysis For The Evaluation Of Neuromuscular Disease

Neuromuscular disease has become one of harming human health and life's significant disease and there is no radical treatment for it at present. So, prompt detection and diagnosis has great meaning in prevention, therapy, drugs research and rescuing patients'life. For now, a variety of treatments for neuromuscular disease diagnosis assessment, but they may have certain limiting factors in the process of operation. However, Local Bioimpedance Analysis (LBA) provides a completely new, invulnerable method for the evaluation of neuromuscular disease.Studies have shown that neuromuscular disease patients'structure of muscle fibers and physiological properties have changes comparing with normal group, and localized bioimpedance parameters have definitive link with these kinds of changes. The paper introduces measurement system of LBA for evaluation of neuromuscular disease depending research situation at home and abroad and actual functional demand. The system uses powerful and generally applicable PIC microcontroller to main control chip, through control direct digital frequency synthesizer DDS to create automatic changing sine signals at frequencies from 2K to 300 KHz as excitation sources, and then, measuring voltage signal which involves local impedance data on the basis of LBA, to finally obtain the amplitude and phase of localized impedance. The measurement system can be used in the measuring localized impedance directly, which effectively overcomes existing equipments disadvantage and meet the portable tide. It has a significant and practical worth.Depending on the functional requirements of neuromuscular disease assessment based on LBA, this paper takes PIC18F4585 Microcontroller and C Language as the system control units, with other functions including Sine Signal Producing Module, VCCS, electrode system, preamplifier, phase measurement, A/D converter and serial communications. This paper introduces in detail the design principle, process of single circuit and the driver structure processes. The applied results show that the system is of good performance by debugging the whole circuit and experimental tests. Within the normal range of the human localized bioimpedance level, relative errors of average amplitude of frequencies by the present method are less 2% and absolute errors of average phase roughly holds 1%.