基于单片机的人体脉搏检测系统设计外文翻译资料

外文文献：

Piezoelectric sensor determination of arterial pulse wave velocity

Arterial pulse wave velocity (APWV) is a measure of the elasticity (or stiffness) of peripheral arterial blood vessels. The pulse referred to here will be the pressure pulse as opposed to the flow pulse measured by ultrasound Doppler.

The pressure pulse velocity varies over the range from about 12 m sminus;1 to

15 m sminus;1 in stiff peripheral arteries, whereas in normal arteries it has a velocity in the range of 7 to 9 m sminus;1.

The aim of this project was the development of a fast and easy to use system for the determination of peripheral arterial pulse wave velocity. The principle of the PWV measurement is based on simultaneous measurement of two pulse waves at two different positions, such as the radial artery at the wrist and the brachial artery just above the elbow. By determining the pulse transit time between these points and the distance measured between the two locations, pulse wave velocity may then be calculated. The pressure pulse detection is done by using two piezoelectric sensors which generate a measurable voltage at the output contacts if they are mechanically deformed. The deformation produced voltage is first amplified and filtered and then digitalized with a data acquisition card. The analysis of the data obtained from the sensors includes a filtering process, the calculation of the PWV with three different methods— foot-to-foot, cross-correlation and peak-to-peak—and the determination of the arterial pulse rate.

The sensor technique used in this work involves the piezoelectric effect in polyvinylidene fluoride (PVDF), which produces an output voltage in response to mechanical pressure on the material.

Three methods of APWV determination are used: foot-to-foot APWV; peak-to-peak APWV and cross-correlation APWV. The FFAPWV and CCAPWV methods are less sensitive to pressure wave reflections at bifurcations, etc in the arterial tree, than the PPAPWV method. Mean values and standard deviations were computed for all three methods and compared.

lsquo;Foot-to-footrsquo; APWV (FFAPWV). This is based on the velocity of the lsquo;footrsquo;, or leading edge, of the pressure pulse wave. The arrival times of the foot of the pulse wave at two positions along the artery are recorded. If Delta;t is the difference in arrival times and Delta;s the distance between the two recording positions (proximal and distal), the FFAPWV is simply

FFAPWV = Delta;s/Delta;t.

lsquo;Peak-to-peakrsquo; APWV (PPAPWV). This is completely analogous to the FFAPWV except that the points of observation are the two (proximal and distal) peaks of the pulse wave and

PPAPWV = Delta;s/Delta;t.

Apparent pulse wave velocity (AAPWV). The pressure wave may be represented as a

Fourier series,

P(t) = P0 Pn sin(nomega;t theta;n)

Where P0 is the mean fluid pressure, n is the harmonic number, Pn is the amplitude of the nth harmonic and theta;n is the phase angle of the nth harmonic.

The spatial rate of change of the phase for one harmonic based on two simultaneous pressure measurements separated by a distance _s along an artery, is related to the apparent arterial pulse wave velocity (AAPWV) by the following equation,

AAPWVn = (Delta;s)n(f )(360^o)/(theta;x1minus; theta;x2)

Where AAPWVn is the apparent pulse wave velocity for the nth harmonic, f is the heart rate,theta;x1 is the phase angle for the proximal harmonic n and theta;x2 is the phase angle for the distal harmonic n.

Cross-correlation PWV. If the arterial pulse at the proximal measurement position is represented by the pressure time series P(x1, t) and that at the distal position by P(x2, t) and

the cross-correlation coefficient is Phi;x1,x2(tau; ), then Phi;will have a maximum value at some time lag.

The correlation function can be expressed as

Phi;x1,x2(tau; ) = (1/T )P(x1, t)P(x2, t) dt.

The value of tau; at which maximum correlation occurs represents the transit time (_t) of the pressure wave from position x1 to position x2 along the arterial segment. From the separation distance and transit time data the correlation arterial pulse wave velocity is

CCAPWV = (x2 minus; x1)/ Delta;t.

In this work normal, young test subjects were used, and it has the primary objectives of optimizing the measurement procedures and establishing the statistical spread and mean values of the observed PWVs for a specific peripheral arterial segment. Based on this, it is planned to use the system in clinical trials involving patients with peripheral arterial disease (due to diabetes, hypertension, etc), pre-, during and post treatment (pharmaceutical or surgical).

Analogue and digital circuitry

Analogue charge amplifier. Piezoelectricmaterials convert mechanical stress or strain into proportionate electrical energy, by producing a charge when subjected to mechanical stress. The charge is converted to a voltage by an operational amplifier connected as a current integrator, called a charge amplifier. The signal output of the amplifier is approximately minus;30 mV. It is augmented by signal amplification.

Analogue signal amplification . This is done by use of an inverting amplifier. Because a dc signal appears at the output of the charge amplifier, dc offset removal is essential and is implemented in the inverting summing

The next phase of the analogue circuitry is a low pass filter to remove the 50 Hz noise interference.

Digital controlled data acquisition and analysis. A data acquisition board (DAQ) is required when the transducer signals need interfacing with a PC. The board contains 12 bit plus sign and a successive approximation and self-calibrating analogue-to-digital (ADC) conver

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中文翻译

压电传感器测定动脉脉搏波速度

动脉脉搏波速度(APWV)是一个测量的弹性(或刚度)的外周动脉血管。这里提到的脉冲将压力脉冲,而不是流脉冲多普勒超声测量。压力脉冲速度变化范围从12msminus;1到15msminus;1,而在正常动脉有速度范围,在7到9 msminus;1。

本项目的目的是开发一个快速且易于使用的外周动脉脉搏波速度测定系统。PWV测量仪的原理是基于同时测量两个脉冲波在两个不同的位置,比如桡动脉在手腕和上臂肱动脉略高于肘部。通过确定这些点之间的脉冲传输时间和两个位置之间测量的距离，可以计算出脉冲波速。压力脉冲检测是通过使用两个压电传感器来完成的，如果输出触点发生机械变形，压电传感器会在输出触点上产生可测量的电压。变形产生电压是第一放大和过滤,然后用数据采集卡数字化。从传感器获取的数据分析包括滤波过程、用三种不同方法计算PWV（英尺到英尺）、互相关和峰到峰以及确定动脉脉搏率。。

本工作中使用的传感器技术涉及聚偏氟乙烯（PVDF）中的压电效应，它根据材料上的机械压力产生输出电压。

三种测定动脉脉搏波速度的方法是: foot-to-foot APWV; peak-to-peak APWV and cross-correlation APWV。FFAPWV和CCAPWV方法不敏感,压力波反射在分支等在动脉树,比如PPAPWV方法。平均值和标准偏差是这三种方法分别要计算并比较的。

lsquo;Foot-to-footrsquo;APWV (FFAPWV)。 这是基于压力脉冲波速度的“脚”,或前缘。脚的到达时间的脉冲波在两个位置沿动脉被记录。Delta;t是到达时间之差和Delta;s是两个记录位置(近端和远端)之间的距离,FFAPWV是

FFAPWV =Delta;s /Delta;t。

lsquo;Peak-to-peakrsquo;APWV (PPAPWV)。 这是完全类似于FFAPWV，只是观察点是脉搏波的两个(近端和远端)的峰值

PPAPWV =Delta;s /Delta;t。

Apparent pulse wave velocity (AAPWV)。压力波可以表示为一个傅里叶级数,

P (t) = P0 Pn (nomega;t theta;n)

P0是流体压力,n是谐波数,Pn是第n次谐波的振幅和相位角的theta;n是第n次谐波。

空间变化速度的阶段的一个谐波是沿着动脉基于两个同时压力测量距离Delta;s,与明显的动脉脉搏波速度(AAPWV)由以下方程表示,

AAPWVn = (Delta;s) n(f)(360 ^o)/(theta;x1—theta;x2)

在AAPWVn是明显的脉搏波速度的第n次谐波,f是心率、theta;x1是近端谐波n的相位角，theta;x2是远端谐波n的相位角。

Cross-correlation PWV.。如果动脉脉冲在近端测量位置代表的压力时间序列P(x1,t)、远端位置P(x2,t)和互关联系数的Phi;x1,x2(tau;),然后有一个最大值Phi;将在某个时间滞后。

相关函数可以表示为

Phi;x1,x2(tau;)=(1 / T) P(x1, tau;)P(x2, tau;)dt。

tau;的价值的最大相关性发生代表时间差(Delta;t)的压力波从位置x1,x2位置沿动脉段。从分离距离和时间数据相关动脉脉搏波速度

CCAPWV =(x2minus;x1)/Delta;t。

在这项工作中，使用了正常的年轻受试者，其主要目标是优化测量程序，建立特定外周动脉段观察到的PWV的统计分布和平均值。在此基础上，计划将该系统用于外周动脉疾病（糖尿病、高血压等）、治疗前、治疗中和治疗后（药物或手术）患者的临床试验。

模拟和数字电路

模拟电荷放大器。压电材料机械应力或应变转换成适当的电能,通过产生一个电荷当受到机械应力。电荷转换成电压通过一个运算放大器连接作为当前积分器,称为电荷放大器。信号输出的放大器是大约30 mV。它增强了信号放大。

模拟信号放大。 这是通过使用一个反相放大器。因为一个直流信号出现在输出的电荷放大器、直流偏移切除是必要的,是实现反相求和下一阶段的模拟电路是一个低通滤波器来去除噪声干扰的50赫兹。

数字控制的数据采集和分析。一个数据采集板(DAQ)时需要传感器信号需要用电脑连接。该板包含12位加号和逐次逼近和自校准模拟到数字转换器(ADC)。ADC招致一个系统误差称为量化误差。这是由于有限的决议和模拟输入上限设定在minus;5 5 V,量化误差的A / D转换器在这里使用费用为0.122 mV。

数据采集和分析是通过使用虚拟仪器一个强大的仪器和分析编程语言对个人电脑。

数字数据采集程序。 数据采集电路执行所有的必要的操作与虚拟仪器的数据采集。电路的功能初始化数据采集和读取的数据采集卡。这些数据是存储供以后使用的数据分析程序的一部分。

虚拟仪器程序被称为虚拟仪器(VIs),因为他们的外表和操作类似于测量仪器。一个虚拟仪器,被称为在另一个虚拟仪器是称为子虚拟仪器和类似于在基于文本的语言子程序。

数据采集、分析和表示包含三个主要过程:

(1)数据采集卡的接口硬件到PC。

(2)数据采集程序获取和存储数据在一个电子表格文件。

(3)数据分析进行数字信号处理,计算和现在的结果

脉搏波速计算

1.脉搏波速计算使用峰值检测。计算脉搏波速使用峰值，峰值的位置首先必须确定,以便运输时间的波形峰值之间可以确定。最好的方法就是微分峰值检测的曲线求积法。 如果曲线的一阶导数为零,那么一个极端值可以存在要么一个峰值或一个转折点。有必要进行二阶导数在这一点如果这也是零,那么一个极端的价值存在。第二个脉搏波速测量仪是用来确定PWVcalc,使用时间是被测波峰间时间差。

2.与压力波仪脚检测。VI命名仪确定了。脚前缘(脚)的压力波在上游和下游位置。虚拟仪器命名PWVcalc 再次用于计算测量仪两个前缘从时间之间的分离 (“foot-to-foot” APWV或FFAPWV)。

3.脉搏波速与互相关。脉搏波速的测定与互相关完成与VI CalcPWV命名。 VI是两个部分:一个部分是初始化函数和一个部分为计算CCAPWV。

在所有情况下脉搏波速值聚集在一个数组和均值、标准偏差和方差计算。

传感器定位

传感器的安置对于保持一致性至关重要。一个螺丝机制是第一次使用的传感器应用到皮肤。但是读物的变量很大,所以这种技术取而代之的是由从传感器固定在皮肤弹性带。这是最好的结果。

臂位是另一个关键特性的测量。两个位置,正常的和依赖,都进行了详细分析,使用一个测试主题。在正常位置,这个主题坐着手臂枕在一个表。所有测试主题数据均在这个位置。在相关位置,主体位于手臂垂直悬的。脉搏波速的价值观在这个位置上,小的差异是大得多,所以这技术被丢弃。

一个校正模块,删除不正确的,是用来删除脉搏波速测量仪产生的值异常的信号,通常由臂运动引起的在测量。这些不现实的价值观被删除之前的值被传递给该脉搏波速分析虚拟仪器。

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