Design Of A Portable Physiological Signal Acquisition System

In recent years, the accuracy of physiological signal acquisition system isgradually improved, and the volume&power of the system are also reduced. All thisdiversification makes the system portable. For the problem of single device can onlycapture a specific physiological signal, but can not be multi-purpose usage, wedesigned a portable multi-functional physiological signal acquisition system. Thissystem has high precision, portability, and can collect a variety of physiologicalsignals, such as EEG, ECG.This paper briefly summarized the amplitude-frequency characteristic ofcommon physiological signals, elaborated on the process of the overall system designand key components selection. The system consists of master and slave machinewhich communicate by USB interface.The key components of the slave machine as follows: the analog front-end chip(The ADS1298), the controller chip (the STM32) and USB isolation chip (TheADuM4160). ADS1298is an8-channel24bit analog to digital converter chip,integrated internal preamplifier, the right leg drive circuit, and the data converted bythe chip transfer to STM32through the SPI bus. The STM32controls the whole slavemachine, and then obtains the data from the ADS1298; it sends data to the hostcomputer by USB interface. The ADuM4160chip electrically isolates between themaster and slave machine, the slave machine uses a battery-powered. The mastercomputer receive data by using the NI-VISA USB driver, and use the Labviewgraphical programming to achieve functions, such as digital filtering, signalamplification, physiological signal waveform display and storage.Referring to the "V model" test， integration testing, system testing andacceptance testing have been taken. The test results show that, the system prototypemeets the design requirements, and the system could measure EEG and ECGmeasurements through certain configuration,4.3μV for EEG noise level and8.7μVfor ECG noise level. The system prototype continued to work for longer than48hours,the hardware circuit size of only102×76×30(mm×mm×mm), easy to portableuse.