8 ~ 14 October 2012 (Week 11)

Title of Activity

-Project research - the PPG waveform .

-Make it as literature review.

Objective

-To know about the PPG waveform .

Content / Procedure

Surf the internet for some information about PPG waveform .

Measurement system 

 

           A schematic diagram of the equipment used is shown in Figure 1. For photoplethysmographic (PPG) measurements the finger clip sensor (Nellcor Durasensor analog) was used (Fig. 1, block 1). The special laboratory instrument for PPG signal amplifying was designed (block 2). The scheme contains two Light Emitting Diodes (LED): red and infrared. The current in LEDs is limited by consistently connected resistor 150 ohm. Both LEDs are multiplexed on two contacts of the sensor. 

By changing polarity of a current it is possible to switch LED s  but  it is impossible to run both simultaneously. A special National Instruments data acquisition board (DAQ) PCI-MIO-16E-1 (block 3) to digitize the signals locally and transmit the digital data to the personal computer with sampling rate 500Signals from finger sensor are amplified by the PPG signal amplifier and then the signal is directed to the DAQ board where acquisition and analog-to-digital conversion take place. Once data is acquired and received it is possible to process and manipulate it. The LabVIEW software packet (block 4) consists of the following programs: main program for data acquisition; program for signal analysis; program for calculations.  

 

     

The waveform analysis was performed to assess the PPG characteristics. The waveforms were analyzed offline using LabVIEW programs. The computer program displayed the incoming waveform  on the screen of the computer. The minimum and maximum threshold (further P1 and P2) and valley (V) values were used as marks for signal analysis and comparison.  To locate necessary points of signal five markers were used.  Marker 1 characterizes the location of the first foot of the pulse. Marker 2 characterizes the location of the first peak. Marker 3 characterizes thelocation of the second peak. Marker 4 characterizes the location of the valley.  Marker 5 characterizes the location of the 

second foot (Figure 2).  

Result & Analysis

-Get the knowledge of PPG waveform .

-To know the PPG pulse recognition.