Bio-neural electrode amplifier system design and implementation (1)

0 introduction

Biological signal diversity of forms, such as: Physics of sound, light, electricity, power, and other types of change; and the concentration of chemical, gas pressure, pH, etc.

Its characteristics are a weak signal, nonlinear, high internal resistance, interference factors more and more, to reflect the status of living organisms, so life activities, biological signal acquisition and processing is a biological sciences research one of the important means.

And biological neural electrode amplifier system (hereinafter referred to as electrical detection system) applications for surgery for patients to monitor brain neural regions, while the inside has a similar instrument system, but the domestic design most confined to one part of the preamplifier, and lack of systemic; while abroad is already shaping the system, but is expensive, and subsequent processing of signals using digital yet.

In contrast, the EMG signal detection system highlights the systemic, constitute a complete instrument, using a digital solution, for system improvement for future digital provides space.

At the same time, the system costs around $ 2000 probably, foreign products, such as Germany's Neurosign100, price is about $ 10 million, the cost is significantly reduced. In addition, due to be developed, owns intellectual property rights.

1 Introduction to neural/EMG

Application of EMG measurement system is the direction of the operation for patients brain neural regions to monitor the approach shown in Figure 1.

First to produce a continuous role of neural signals from one end of the nerve, and then to the other end of the nerve is connected to the muscles on the extraction of EMG zoom, filtering, processing, and finally to LED display and sound, for real-time detection of the nerve is in operation is encountered in the process.

Therefore, for the design of the amplifier system, you need to generate a type of neural signals as an incentive for the signal, and the required biological signals amplified for EMG.

Neural signals and other human biological signals have the same features, but also has its unique features. According to research in neurobiology, nerve signals is a kind of takes the pulse of electrical signals, about General be 1 kHz frequency, the higher up to 10kHz; and should provide the pulse width, pulse peak 0.2ms as 0.05mA ~ 1mA, frequency 30Hz 3Hz and have two choices.

2 circuit design

Electromyography test system including stimulation circuit, amplifier and filter circuit and display processing circuit, but also carried out for electrode design including the probe, the expected results as shown in Figure 2.