The Development of a New Three-channel Self-pressurized

Wrist Pulse Acquisition System

Zhou Kan-Heng

, Qian Peng

, Xia Chun-Ming

and Wang Yi-Qin

School of Mechanical and Power Engineering, East China University of Science and Technology,

No.130 MeiLong Road., Shanghai, China

School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China

Keywords: Three-Channel, Piezoresistive Pressure Sensors, Best Pulse Taking Force, Three Regions and Nine Pulse-

Takings, Automatic Self-Pressurized Control.

Abstract: A new three-channel self-pressurized pulse acquisition system based on the principle of wrist pulse

diagnosis in Traditional Chinese Medicine (TCM) was introduced in this paper, including the hardware and

the software design of this acquisition system. This acquisition system can not only get three-channel wrist

pulse waveforms under the best pulse taking force through the automatic pressure control module composed

of stepper motors and ball screw pairs, but also simulate the process of the three regions and nine pulse-

takings wrist pulse diagnosis in TCM. Besides, this acquisition system also can real-timely display and store

three-channel wrist pulse waveforms. It can been seen that this wrist pulse acquisition system solved the

problem that only the pulse waveforms in Guan region of the wrist can be detected, which does most of the

existent pulse acquisition systems have. The system provided a user-friendly flexible sample collection

platform, laid the foundation for analyzing the multi-channel wrist pulse waveforms and pushed forward the

development of the standardization of wrist pulse waveforms and the objectification of wrist pulse diagnosis

in TCM.

1 INTRODUCTION

In TCM theory, the diagnosis and the treatment of

diseases are mainly based on wrist pulse diagnosis,

which is pretty hard to learn. Therefore, modern

people long for a kind of objective pulse detection

and description method to systematically explain the

principle of wrist pulse diagnosis in TCM (Li Jing-

tang, 2001).

Recently, with the development of sensor

technolygy, domestic and foreign researchers have

already invented a series of pulse detectors to

acquire and analyze wrist pulse waveforms, such as

MX-811 pulse detector made by Nanchang Radio

Instrument Factory, BSY-14 pulse detector made by

Beijing Medical Factory, MX-3 pulse detector made

by Shanghai Medical Research Institute, MTY-A

pulse detector made by Tianjing Medical Research

Institute, ZM-III pulse detector made by Shanghai

University of Traditional Chinese Medicine and

CMB-3000/2000 pulse detector made by Japan

Colin company. Although these pulse detectors have

described and analyzed wrist pulse waveforms from

various aspects, most of these pulse detectors only

have a single-probe sensor, which can only detect

the pulse in one region of Cun, Guan and Chi of the

wrist, as shown in the figure 1 below, and mainly

detect the pulse of Guan region. These pulse

detectors simplified the precisely multi-dimensional

sensor of doctor’s finger with a single-probe sensor.

Therefore, the wrist pulse waveform sampled by

these detectors does not carry complete information

of wrist pulse (Fei Zhao-fu, 2003). In addition, the

pulse sampling way of these pulse detectors differs

form the pulse feeling of “three regions and nine

pulse-takings” in TCM clinical science. The pulse

feeling of “three regions and nine pulse-takings” is a

triditional way of pulse feeling, in which the wrist

pulses in the region of Cun, Guan, Chi are felt

respectively and the wrist pulse in each region is felt

under the floating, medium and sinking pulse taking

pressures. Therefore, there are totally nine pulse-

takings.

In order to conform to the pulse feeling of “three

regions and nine pulse-takings” in TCM clinical

science, our research group developed a new three-

channel self-pressurized pulse acquisition system.

Kan-Heng Z., Peng Q., Chun-Ming X. and Yi-Qin W..

The Development of a New Three-channel Self-pressurized Wrist Pulse Acquisition System.

DOI: 10.5220/0005199400230028

In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2015), pages 23-28

ISBN: 978-989-758-071-0

 2015 SCITEPRESS (Science and Technology Publications, Lda.)

1－Chi region 2－Cun region 3－Guan region

Figure 1: The region of Cun, Guan and Chi.

This acquisition system can not only acquire three-

channel wrist pulse waveforms under the best pulse

taking force through the automatic pressure control

module composed of stepper motors and ball screw

pairs, but also simulate the process of the three

regions and nine pulse-takings wrist pulse diagnosis

in TCM. Besides, this acquisition system can real-

timely display and store three-channel wrist pulse

waveforms.

2 DESIGN OF HARDWARE

The three-channel self-pressurized pulse acquisition

system consists of three-probe pulse sensor, signal

pre-processing circuit, automatic pressure

controlling module and data acquisition and

processing system. The diagram below shows the

realization of the hardware.

Figure 2: The block diagram of the hardware of three-

channel self-pressurized pulse acquisition system.

2.1 Design of Three-Probe Pulse Sensor

The three-probe pulse sensor which is composed of

three independent piezoresistive pressure sensors in

the region of Cun, Guan and Chi, as shown in the

figure 4 below, can not only realize automatic

pressure increasing but also simulate the process of

the three regions and nine pulse-takings wrist pulse

diagnosis in TCM.

2.1.1 Principle of Pulse Detection

Among many kinds of pulse detection methods,

ergography, which is more in line with the pulse

feeling in TCM, is one of the most widely used

method in the field of pulse detection. Therefore,

three-probe pulse sensor applied the basic principle

of ergography. The diagram below shows the

physical model of each piezoresistive pressure

sensor with the same design parameters.

1 － aluminium alloy case 2 － piezoresistive pressure

sensor chip 3－liquid 4－aluminium alloy film 5－skin

6－blood vessel

Figure 3: Physical model of piezoresistive pressure sensor.

When aluminum alloy film 4 applies pressure

onto “skin 5 and blood vessel 6” system round the

radial artery (equal to the floating, medium and

sinking pulse taking pressure with fingers), the

aluminum alloy film 4 detects the reaction force of

pulse taking force  and pulse force ∆ (Tang Wei-

chang, 2005). Because of the incompressibility of

liquid, the resultant force of these two forces is

transferred to piezoresistive sensor chip 2 and makes

the resistivity of the sensor chip 2 made by

semiconductor material changes. The signal pre-

processing circuit, attached by the sensor chip 2,

outputs signals in different levels with the changes

of resistivity caused by the changes of ∆, so

different pulse taking forces and different pulses are

able to be distinguished according to different

signals, so as to realize qualified detection of pulse.

2.1.2 Parameters of the Pulse Sensor

All pulse sensors applied in three-probe pulse sensor

are piezoresistive pressure sensors (NPI-12-101GH)

manufactured by GE. Each sensor applies silicon

elastic thin film as pressure sensitive element and

measures pressure through the pressure electricity

BIODEVICES2015-InternationalConferenceonBiomedicalElectronicsandDevices

conversion circuit, the Wheatstone bridge circuit,

which is composed of 4 same resistance resistors

fabricated by MEMS technology. Compared with

the pressure sensor applied traditional metal strain

foil, the sensitivity of this sensor is 50~80 timers

higher. In addition, there is no mechanical linkage,

therefore, the measurement accuracy of this sensor is

relatively higher and the repeatability error and

pressure hysteresis effect of this sensor are much

lower. After testing, the main static capability

indexes are as follows:

Sensitivity: 10mV/gram-force;

Linear range: 0~1000 gram-force;

Accuracy: 0.1%;

Working temperature: 10 ~ 40;

Composite error of linearity, pressure hysteresis

effect, repeatability and temperature error: <4%

FSO.

2.1.3 Structure of Three-Probe Pulse Sensor

In order to simulate the process of the three regions

and nine pulse-takings wrist pulse diagnosis in

TCM, the structure of three-probe pulse sensor can

not only realize acquire wrist pulse waveforms

simultaneously in the region of Cun, Guan and Chi

under various pulse taking forces, but also realize

the adjustment of the axial relative distance and the

radial relative distance of these three separate pulse

sensors. Figure 4 shows the structure of three-probe

pulse sensor and figure 5 shows the structure of

three-channel self-pressurized pulse acquisition

system.

1－sensor of Chi region 2－sensor of Guan region 3－

sensor of Cun region 4－x-axis position adjustment knob

5－x-axis threaded shaft 6－pressure controlling module

of Cun 7－pressure controlling module of Guan region 8

－ pressure controlling module of Chi region 9－ fixed

bracket 10 － y-axis fixed knob 11 － y-axis position

adjustment knob

Figure 4: The structure of three-probe pulse sensor.

1－base 2－wirst bracket 3－sliding guide table

4 － connecting plate 5 － x-y axes precise manual

adjustment platform 6－three-probe pulse sensor

Figure 5: The structure of three-channel self-pressurized

pulse acquisition system.

As can be seen form figure 4, three separate

pulse sensors are attached to their own pressure

controlling modules and these modules attached to

the fixed bracket by various directions adjustment

mechanisms which are all screw transmission

mechanisms. The sensor of Guan used as location

basis can only adjust the position along z-axis, while

the sensor of Cun and Chi can not only adjust the

position along z-axis via automatic pressure

controlling module, but also adjust the distance

relative to the sensor of Guan along x-axis via the

knobs on both sides so as to adapt to the different

patients with different relative distance among the

region of Cun, Guan and Chi. In addition, the sensor

of Cun and Chi can also adjust the distance relative

to the sensor of Guan along y-axis via the knobs on

the front panel so as to adapt to the inconsistency of

the axial physiological curve of radial artery. The

feature of the three-probe pulse sensor, which can

adjust the position of three separate sensors flexibly

along the axes of x, y and z, makes it can simulate

the process of pulse feeling in TCM.

As can be seen from figure 5, compared with

most pulse sensors that fixed with wristlet, three-

probe pulse sensor is fixed on a precise manual

adjustment platform. The wrist is laid on the wrist

bracket under the three-probe pulse sensor when

acquiring wrist pulse waveforms, which can not only

avoid the measurement error caused by the excessive

deformation of soft tissue because of fixed with

wristlet, but also be more in line with the form of

pulse feeling in TCM clinical science.

TheDevelopmentofaNewThree-channelSelf-pressurizedWristPulseAcquisitionSystem

2.2 Signal Pre-Processing Circuit

The signal pre-processing circuit consists of mixed

amplifier, pulse signal amplifier, pulse taking

pressure signal amplifier and output circuit.

Each mixed amplifier amplifies the pulse taking

pressure and the pulse signal that detected by the

pulse sensor. In order to keep the amplified signal

stable and low-noise, instrumentation operational

amplifier, which has advantages of low noise, low

drift, low power consumption, high consistency and

strong anti-interference ability, is applied.

Each pulse signal amplifier consists of band-pass

filter and general operational amplifier. Because

there is DC component in the original signal

amplified by the mixed amplifier, which will cause

the output signal saturation and distortion if this

signal is put into the main amplifier directly, so as to

amplify the pulse signal (AC component of the

original signal), band-pass filter is applied to remove

this DC component in the signal. At the same time,

appropriate time constant should be calculate

according to the frequency characteristics of pulse

signal.

Each pulse taking pressure signal amplifier

consists of low-pass filter and general operational

amplifier. Low-pass filter is used to get the low-

frequency component of the original signal and

general operational amplifier is used to amplify the

low-frequency component of the original signal. The

amplification factor should not be too large to cause

the output signal saturation.

Each output circuit is an adder circuit that

consists of general operational amplifier. And the

function of the output circuit is to synthesize the

complete wrist pulse waveform involving the pulse

taking pressure and the pulse signal. Then, this wrist

pulse waveform is transmitted to the data acquisition

and processing system to real-timely display and

store.

2.3 Automatic Pressure Controlling

Module

The automatic pressure controlling module, which is

applied to realize automatic compression in the

region of Cun, Guan and Chi, but also can simulate

the process of the three regions and nine pulse-

takings wrist pulse diagnosis in TCM, is composed

of three independent screw mechanisms and

stepping motors. Data acquisition and processing

system calculates the pulse taking pressure of each

channel and analyzes the peak-to-peak value of wrist

pulse waveforms to find the best pulse taking force.

And at the same time, it sends commands to

automatic pressure controlling module to adjust the

position of each sensor along z-axis to ensure these

sensors acquire wrist pulse waveforms under the

best pulse taking force. Some researchers have

studied on the range of the pulse taking pressure that

human body can endure and find the upper limit is

261.19 gram-force (Wang Jing-jing, 2010).

Therefore, the maximum setting of the pressure

range of the automatic pressure controlling module

limited by the software and hardware is 0 ~ 250

gram-force.

2.4 Data Acquisition and Processing

System

After A/D conversion, three-channel pulse data,

which acquired under the best pulse taking force, is

uploaded to the host computer through serial

communication. Data acquisition and processing

system mainly realize real-timely display of the

wrist pulse waveforms, real-timely calculation of the

pulse taking pressure and dynamic pulse data

storage, which lays the foundation for analysis of

multichannel wrist pulse waveforms.

3 DESIGN OF SOFTWARE

The software of three-channel self-pressurized pulse

acquisition system is composed of Micro Control

Unit (MCU) data acquisition program and PC data

processing software.

3.1 MCU Data Acquisition Program

The MCU, applied in three-channel self-pressurized

pulse acquisition system to acquire three-channel

pulse data, is a STM32 series chip, whose kernel

architecture is ARM Cortex-M3. MCU data

acquisition program, which simulates the process of

the three regions and nine pulse-takings wrist pulse

diagnosis in TCM, uploads the three-channel wrist

pulse waveform samples acquired under various

pulse taking pressures to the host computer. At the

same time, the host computer calculates the pulse

taking pressures and the peak-to-peak value of wrist

pulse waveform samples to search for the best pulse

taking force. After finding the best pulse taking

force, the host computer sends it back to MCU to set

the pulse taking pressure to the best one via

automatic pressure controlling module. And then,

MCU filters the signals with sliding filter, samples

BIODEVICES2015-InternationalConferenceonBiomedicalElectronicsandDevices

the wrist pulse waveforms under the best pulse

taking force and uploads the best wrist pulse

waveforms to the host computer through serial port.

3.2 PC Data Processing Software

Three-channel self-pressurized pulse acquisition

system applies personal computer as the host

computer to receive the three-channel pulse data sent

from MCU and do corresponding processing. This

computer data processing software, which is written

by C#, is based on the Microsoft .NET Framework 4.

The interface of the software is shown in figure 8.

This data processing software can not only real-

timely display three-channel wrist pulse waveforms

and their corresponding spectrums, but also real-

timely display current pulse taking pressure in the

pressure display area on the left side. Besides, this

data processing software can also search for the best

pulse taking force through comparing the peak-to-

peak value of two adjacent cycles of the wrist pulse

waveforms and the specific process as shown in

figure 6. Also, this data processing software can

regulate the pulse taking pressure manually through

pressure regulating button. All three-channel pulse

data acquired can be stored into the database

automatically according to the patient’s name,

sampling date and time and other information and

can be loaded form the database for viewing and

analysis at any time.

Figure 6: Searching process of the best pulse taking force.

4 RESULTS

4.1 Result of Pulse Sensor Test

Our research group has carried out the static test of

the pulse sensor between 0 ~ 250 gram-force. Figure

7 shows the result of the linear regression, whose y-

axis represents output voltage (mV) and x-axis

represents input pressure (gram-force). The R-square

of the linear regression is 0.9983, which indicates

the linearity of the pulse sensor is excellent in the

range of normal pulse taking pressure and can detect

the pulse taking pressure accurately.

Figure 7: The result of the linear regression of the pulse

sensor.

4.2 Result of Pulse Acquisition

Figure 8 shows the three-channel wrist pulse

waveforms acquired by the three-channel self-

pressurized pulse acquisition system, which

indicates the acquisition system can get clear three-

channel pulse data and accurate pulse taking

pressure.

5 DISCUSSIONS AND

CONCLUSIONS

All pulse sensors applied in three-probe pulse sensor

are piezoresistive pressure sensors with silicon

elastic thin film, which are fabricated by MEMS

technology. Compared with the pressure sensor

applied traditional metal strain foil, the sensitivity of

this sensor is much higher. At the same time,

because of no mechanical linkage conversion, the

measurement accuracy of this sensor is relatively

higher and the repeatability error and pressure

hysteresis effect of this sensor are much lower.

The three-probe pulse sensor avoids being fixed

with wristlet, while applies wrist bracket to fix the

wrist, which can not only avoid the measurement

TheDevelopmentofaNewThree-channelSelf-pressurizedWristPulseAcquisitionSystem

error caused by the excessive deformation of soft

tissue because of fixed with wristlet, but also be

more in line with the form of pulse feeling in TCM

clinical science.

The PC data processing software of the three-

channel self-pressurized pulse acquisition system

acquires wrist pulse waveform samples under

various pulse taking pressures through slowly

continually compressing and then search for the

pulse taking pressure of the largest peak-to-peak

value of the wrist pulse waveforms as the best pulse

taking force, which is more accurate than that

searching for the best pulse taking force form

several setting pressures and can acquire better wrist

pulse waveforms.

The three-channel self-pressurized pulse

acquisition system can not only simulate the process

of the three regions and nine pulse-takings wrist

pulse diagnosis in TCM and acquire the wrist pulse

waveforms in the region of Cun, Guan and Chi

under the best pulse taking force automatically, but

also real-timely display the pulse taking pressure and

the pulse waveforms of the wrist, which lays the

foundation for analysis of multichannel wrist pulse

waveforms and improving the development of the

standardization of wrist pulse waveforms and the

objectification of wrist pulse diagnosis in TCM.

REFERENCES

Li Jing-tang, 2001. The Objective Detection and

Description of the Types of Pulse Based on the

Chinese Traditional Medical Science. In Chinese

Journal of Medical Instrumentation.

Fei Zhao-fu, 2003. Contemporary Sphygmology in

Traditional Chinese Medicine. People’s Medical

Publishing House Co., Ltd. Beijing.

Tang Wei-chang, Li Rui, 2005. Research on the Cun-

Guan-Chi Pulse Detecting System. In Chinese Journal

of Medical Instrumentation.

Wang Jing-jing, Liu Cong-ying, Jia Xin-hong, etc., 2010.

Research for the Largest and Safe Pressure in the

Pulse Testing. In Liaoning Journal of Traditional

Chinese Medicine.



Qian Peng contributed with Zhou Kan-heng, and they are

both the first author. These authors contributed equally to

this work.

Figure 8: The interface of the software with three-channel wrist pulse waveforms.

BIODEVICES2015-InternationalConferenceonBiomedicalElectronicsandDevices