Design And Implementation Of Signal Acquisition And Amplifying System In Biological Multi-channel Recorder

As one of the leading products in Henan Huanan Medical and Electric Technology Co. LTD, biological multi-channel recorder adopts comprehensively the latest media computer technology and advanced electronic technology as well as digital signal processing. It is invented as a new biological experiment instrument and the ideal products for experiments.This system consists of the computer, biological signal amplifier, stimulator, DSP processing, A/D converter, and software for displaying and disposing. These elements can realize the collection, record and analysis of multi-channel biological signals. By means of the system, it is able to acquire the electric signals and non-electric signals from living organisms or tissue samples with excitability in vitro. They are displayed after being amplified, collected, transferred and analyzed. This system has been widely used for the teaching and scientific experiments for physiology, pharmacology, clinical medicine and so on.The biological multi-channel recorder is an updated product of traditional system for traditional medical experiments with controlled programs and functions to collect, display, record and analyze eight-channel biological signals. It possesses advantages like high-precision, high-availability and wide scope of application. This instrument is with a new framework used for the collection and analysis of data of biological research and teaching. It applies USB-based general line and the structure with large scale programmable integrated circuit and FPGA technology. Its experimental processing system is composed of three main parts, micro computer, biological multi-channel hardware and software. The WIN2000/WINXP-based system software transmits the data collected by hardware to upper application through USB 2.0 completely and effectively. The data collected can be integrally imported into other applications (Excel, Word) in Windows, which is convenient for data sharing.There are a large amount of factors in human body which can impact biomedical signals. The human biological signals are generally with the features of weak signals, loud noise, low frequency scope and strong randomicity. So it is feasible to design a stable, effective signal amplifier system with low noise to conform to acquirements. Inside the multi-channel recorder, the collected electrical data are amplified and filtered through different types (including HPF, LPF and limit waves in specified frequency). Te amplifier module and other modules are shielded separately to avoid the interruptions of other modules. Then the disposed signals are digitalized by AD conversation module. Afterward it is able to transmit the digital signals into the computer by means of USB 2.0 transmission lines.Signal acquisition circuit is composed of filtering and amplifying circuit by use of chips. It applies MC14051, MC14052 chips to feedback resistance circus by selecting the signal frequency and amplifier. As cell-type gain circuits being composed of chip 74HC57, the hardware magnification is simultaneously controlled by upper computer program input signal.In this essay, it achieves the design of the circuit for the selection and analysis of the signals in the biological multi-channel recorder. The circuit includes HPF circuit, LPF circuit, limit waves in specified frequency and so on. Moreover, it consists of controllable preamp amplifier circuitry and lower amplifier circuitry composed of MC14052 chip and the controlling circuit composed of 74H57. In addition, it records the data of signal testing after completing the circuit.