| Biology electric impedance is a kind of physics quantum reflecting the electrics character of biology tissue. The biology electric impedance technology, which is a kind of detection technique without trauma, is to distill biomedicine information related to physiology or pathology according to the electricity characteristic or the change of biology tissue. Its application in medicine domain is very general. Since 1981, that Lanner researched the brain impedance and ICP about patients who were sufferring cerebrovascular decompensation, and proved that ICP and brain impedance are relative, the application of biology electric impedance to monitor intracranial pressure without trauma has been given much attention.This paper design a non-invasive system to monitor ICP based on the biology electric impedance technology. The theory and method in the realization of non-invasive ICP measuring system is researched in this paper. On the theory aspect, the possibility of monitoring intracranial pressure by meas of biomedical impedance is discussed. On the realization aspect, this paper analyzed the design process of the whole hardware and software system. The hardware system design includes the collectivity structure design and the interior structure design of the modules.At the source part, the constant-current source module of the hardware system is designed through the direct digital synthesis technique, with the direct digital synthesis integration CMOS chip AD9850. The module can generate high accurate and steady sinusiod signal with error less than 0.6%, and its output resistence is about 941K?. The measuring part is composed of high-powerd differencial amplifier, high pass filter and notch filter. Then the amplitude of impedance signal is obtained through an switch demodulator. The voltage signal then is sampled by a data aquisation card, and is displayed, analysised and saved by the software designed with VC++.
|
PDF Full Text Request