1. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
– 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 2, February (2014), pp. 83-92 © IAEME
83
MEASUREMENT OF HUMAN BLOOD CLOTTING TIME USING LabVIEW
Bharati. S R1
, Parvathi. C S2
and P. Bhaskar2
1
Department of Electroncs, Nutan Vidalaya Degree College, Gulbarga-585103, KA, INDIA
2
Department of Instrumentation Technology, Gulbarga University, P.G. Centre, RAICHUR-584133,
KA INDIA
ABSTRACT
This paper focuses on development of a system where the human blood clotting time of is
determined by measuring the blood conductivity during coagulation. The minimum amount of blood
sample (1ml) is taken and conductivity cell is immersed into it. The signal produced by conductivity
cell will be in terms of millivolts which is further signal conditioned and acquired by the onchip
ADC of ATMEGA 328 microcontroller. This voltage is converted into corresponding conductivity
by curve fitting methodin microcntroller. The conductivity thus measured is transmitted to PC
through USB. Graphical user interface (GUI) is developed using LabVIEW software. Further
LabVIEW plots the graph of variation of conductivity with respect to time. From the graph, the
clotting time is determined when conductivity becomes almost constant and the same is displayed on
the front panel of the PC. The proposed device has advantages of portability, easy operation and real
time results for monitoring in the healthcare units. The results thus obtained from proposed device is
correlated against clinical test and found efficient and accurate.
Keywords: Blood Coagulation, ATMEGA328, Clotting Time, LabVIEW.
1. INTRODUCTION
The human blood is composed of cells distributed in an aqueous solution. Many charged or
polar molecules are present at both inside and outside the blood cells. Numerous inorganic ions are
distributed through the blood volume. Hence it is a good conductor. And we can measure the
conductivity by feeding small sinusoid amplitude [1].
Blood coagulation is one of the haemostatic processes of humans, which consists of a
complex, physiological cascade. When the blood vessel is damaged, the substances released from the
destroyed endothelium into blood induce formation of a platelet aggregation at first[2,3]. After
activation, platelets tend to adhere to the damaged vessel wall and finally, an aggregated platelet plug
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2. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
– 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 2, February (2014), pp. 83-92 © IAEME
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is formed to prevent the loss of blood. During this process, plasma clotting also happens. When the
cells are placed in endothelium are exposed to blood, the plasma clotting, known as blood
coagulation, is activated. Blood coagulation process has more complex cascade, which consists of
enzymatic reactions in blood plasma [4]. As a result of complicated process, polymerized fibrin is
formed from fibrinogen to prevent the loss of blood cells.
It is important to monitor blood coagulation process because disorders in coagulation can
lead to higher risk of bleeding. Also, blood coagulation disorders have possibilities to bring
pathological complications in increasing thrombosis and embolism in the vascular system[5]. These
are life-threatening, which can induce fatal danger in various clinical circumstances, such as cardiac
surgery [6]. Therefore, it is essential to check the blood coagulation process regularly to allow the
detection of clotting problems.
Clinical laboratory examination of blood coagulation analysis allows observation of the
amount of vitamin K in the blood indirectly and diagnosis of liver disorder. The treatment of drugs
used in some hereditary and hemorrhagic diseases depends on the process of blood coagulation by
measuring the clotting time or prothrombin time [7]. The coagulation of blood is a complex process
during which solid clots are formed in the blood. The conversion of fibrinogen into fibrin and the
subsequent covalent cross-linking of fibrin play important roles in this process, and can be induced
by an imbalance between coagulant and anticoagulant factors. Although coagulating blood is vital to
the preservation of life, blood clots can impede blood flow in the vessels. Thrombus formation is
responsible for most heart attacks and strokes and complicates other pathological conditions such as
coronary thrombosis, peripheral deep venous thrombosis, and pulmonary embolus, and can
eventually cause death unless brought under control [8]. In addition, paralytic patients confined to
bed usually suffer from intravascular clots due to coagulation that tends to occur when the flowing
blood is obstructed for a few hours in any vessel of the body. Therefore, a clear understanding of
blood coagulation properties is crucial for clinical diagnosis, and techniques for detecting blood
coagulation need to be developed. A common method to assess the process of blood coagulation
involves adding blood to three or four test tubes and then tilting the tubes at 30-s intervals until the
blood can no longer flow. Clotting time is used as a screening test to measure all stages in the
intrinsic coagulation system and to monitor heparin therapy [9].
LabVIEW is visual programming software developed by National Instruments. LabVIEW is
an acronym for Laboratory Virtual Instrumentation Engineering Workbench. It is used in testing,
automation, instrument control, and monitoring and data acquisition. Programming is done by
connecting icons together to form a visual flow chart of processes. There is no code or syntax to
memorize or acronyms to learn. Programming is like drawing a flowchart [10].
LabVIEW is growing in popularity. LabVIEW is completely graphical in its programming
and visualization of the data and controls [11]. The program that we create is called VI the Virtual
Instrument. Within this VI there are two screens. The front panel is the GUI (Graphical User
Interface) where the human interacts and monitors the program while it is running. The front panel
contains the voltage readings and the measurements etc. The block diagram contains the
programming working behind the front panel. Just like wires, switches and circuits would work
behind an instrument panel. The block diagram is icons wired visually together to create a flowchart
of the program. Icons represent the functions of what is being controlled and wires contain the data
that connects the icons together [12]. The present work utilizes LabVIEW 12.0 version.
Literature survey on measurement of human blood clotting time reveals that many
researchers re have done measurement using different techniques. George S Sutton has done
measurement using Lee & White method [13]. Hyunjung Lim et al have done measurement using
Light Transmission method where co-agulation of blood is measured by intensity of the light
transmitted [14]. Robert A Schneider et al have done measurement by observing viscosity of blood

3. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
– 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 2, February (2014), pp. 83-92 © IAEME
85
during Coagulation [15]. Chih-Chung Huang et al, have studied the coagulation by Ultrasound
Elastography Method [16].
The measurement methods as mentioned above authors are found to be time consuming and
complex. This motivated us to design an instrument to measure human blood clotting time by
measuring electrical conductivity which is found to be fast and easy compared with conventional
analysis techniques. This work is valuable for the development of clinical equipment for routine
coagulation tests.
2. HARDWARE DETAILS
In this manuscript, we present a new blood coagulation monitoring method using LabVIEW.
Fig. 1 shows the block diagram of the microcontroller based human blood conductivity measurement
system.
Fig 1. Block diagram of human blood clotting time measurement system
It consists of
• Conductivity cell
• Signal conditioning circuit
• Microcontroller
• PC
The complete schematic diagram of Atmel microcontroller based human blood conductivity
measurement system is shown in figure 2.
Microcontroller
ADC
SerialPort
Sine wave
Generator
(1Khz)
R
R
R
C
Instrumentati
on
Technology
AmplifierRectifier
and filter
PersonalComputer
LabView
Monitor
Keyboard

4. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
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Fig 2. Schematic diagram of human blood clotting time measurement system
i. Conductivity Cell
The conductivity cell consists of a pair of electrodes that are firmly located in a constant
geometry. The cell used in the present study consists of two platinum electrodes of 1 cm2
cross
sectional area that are separated by a distance of 1 cm. the cell constant of the cell used in the present
study is 1.01. [Elico manual]
ii. Signal Conditioning Circuit
The proposed signal conditioning circuit is designed for this particular application which
utilizes AC conductivity measurement. This circuit consists of a stable sine wave oscillator
constructed by using an operational-amplifier {WEIN-BRIDGE OSCILLATOR}. This oscillator is
designed to generate a sine wave frequency equal to 1 KHz at amplitude equal to nearly 10 VPP. The
generated AC sine wave is used as an excitation source for the impedance bridge containing a sample
in one of the bridge arm. The AC excitation source is capacitively coupled or coupled through the
capacitor to the bridge. The differential voltage is amplified using differential amplifier designed by
using an operational amplifier. The differential gain can be varied from 1 to 10. The amplified
differential output is further amplified by another with maximum gain of 10, thus amplified AC
voltage is rectified and filtered to get the average DC voltage, corresponding to the conductivity of
the blood sample. This analog output is converted to 10 bit digital data by using an ADC which is
inbuilt in the microcontroller which is being used.
iii. Microcontroller
In present system ATMEG 328 microcontroller is used. This microcontroller is a high-
performance Atmel 8-bit AVR RISC-based microcontroller combines 32KB ISP flash memory with
read-while-write capabilities, 1KB EEPROM, 2KB SRAM, 23 general purpose I/O lines, 32 general
purpose working registers, three flexible timer/counters with compare modes, internal and external
interrupts, serial programmable USART, a byte-oriented 2-wire serial interface, SPI serial port, 6-
channel 10-bit A/D converter (8-channels in TQFP and QFN/MLF packages), programmable

5. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
– 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 2, February (2014), pp. 83-92 © IAEME
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watchdog timer with internal oscillator, and five software selectable power saving modes. The device
operates between 1.8-5.5 volts.
3. SOFTWARE DETAILS
The program to acquire the data and to process is written in embedded C languagefor
microcontroller.. The detailed flow chart is shown in figure 3. The conductivity measurement of the
blood can be impacted by various criterions. One among them would be the curve fitting method.
Finally the data is processed using the relation y= mX+C to get the result of the conductivity where
y is voltage acquired by the ADC, X is conductivity of blood , m is slope and C is intercept. The
equivalent conductivity is calculated for each voltage variation.
The result thus obtained is transmitted to PC through USB where the LabVIEW is used for
determining clotting time. A GUI has been designed in LabVIEW for the user sake i.e. for the
display of the result such as clotting time. Figure 4 shows the designed GUI where the information
about results can be viewed. A GUI program is a graphical based approach to execute the program in
a more user friendly way. It contains components with proper labels for easy understanding to a less
experienced user. These components help the user to easily understand how to execute or what to do
to execute the program. When an user responds to a GUI’s components by pressing a pushbutton or
clicking a check box or radio button or by entering some text using text box, the program reads the
necessary information for that particular event, hence GUI programs are also known as event driven
programs.
Fig:3 Detailed flowchart for measurement of conductivity using microcontroller

6. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
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Fig 4 and Fig 5 show the block diagram of the VI designed to plot the graph of variation of
conductivity with respect to time and display of clotting time on the front panel.
Fig 4. VI Block diagram for measurement of conductivity
Fig 5. VI Block diagram for measurement of clotting time.

7. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
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The LabVIEW program is written to acquire the data, to process, to measure and to display
the clotting time on the front panel. The data analysis file is to be kept in the required format and
placed in the a subdirectory. This file path is to be given to the path reference to read. All the
variables such as convert data array, conductivity versus time, array length, clotting time, min and
max values etc are to be initialized for default values or zero. Infinite while loop is executed with
time delay so that other applications need time from cpu to work in multitasking mode and also to
enable the polling of other functions. As the program has to be fit in the same screen stacked
sequence is used which will also make debugging and any modifications simpler. When the program
is running, inside the while loop the various inputs are continuously polled for the relevant input. The
buttons which are polled are Read Data File and Plot buttons. The file path is to be entered to read
the data file.
During polling, pressing the read button, the raw data is read and converted to the tab
separated string format for further processing. The data are further separated and put into two
dimensional array as conductivity in one column and time in another column. Then string formatted
array is converted to floating decimal number array which is required for plotting.
By pressing the plot button, the 2D array is transposed and graph is plotted as conductivity vs
time in the front panel. It will also find the total size of the array which is required for differentiation.
Differential equation is applied for clot conductivity values versus time to find where the clot
conductivity values remain constant. After finding the duration of the clotting time in seconds, which
in turn is expressed in terms of minute and displayed on the front panel. Again the polling will
continue for the next data set from different file to be input. This process will continue till we
terminate the program. Fig 6 shows the front panel of GUI where we can see the display of clotting
time. The detailed flowchart for measurement of conductivity and display of clotting time is shown
in fig 7.
Fig 6. Front panel of LabView showing clotting time

8. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
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4. RESULTS AND DISCUSSION
Fig 8 shows the graphical representation of variation of actual conductivity with respect to
time. It is clear from the plot that the conductivity decreases as time elapses due to disappearance of
conductive ions. Once the blood is clotted, conductivity reduces to great deal and becomes almost
constant.
Fig 7. Flow chart
Initialization of constants and variables
Input path for data file
Start
Is button
pressed?
Read data and display
Convert data into 2 dimensional array
Is button
pressed?
Convert string array to floating array
Plot graph time Vs conductivity
Fine array size
Find out constant dx/df
Conductivity
Find total duration
Convert to minute and display
Next set of data
No
Yes
No
Yes

9. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
– 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 2, February (2014), pp. 83-92 © IAEME
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Fig 8. Variation of conductivity with respect to time
The designed Instrument is subjected to measure the clotting time of 20 individuals. Fig 9
shows the clotting time of each individual measured by the instrument developed and also compared
with the clinical measurements and found that there is 96% of accuracy. The normal range of time
for the blood clotting is 5 to 15 min.
Fig9. Results of testing Sample
5. CONCLUSION
This work demonstrates the development of a system that allows precise detection of the
coagulation time of whole blood by measuring conductivity during coagulation using LabVIEW. The
method is shown to be useful for determination of the blood disorders like lack of hemoglobin,
hemophilia, and hematocrit etc., Clotting time is used as a screening test to measure all stages in the
intrinsic coagulation system and to monitor heparin therapy during major surgeries. In this work,
analysis of the conductance change of blood sample during coagulation was conducted successfully
and results showed that the clotting time measurement using LabVIEW is a sensitive and promising
technique for monitoring blood coagulation process. This method found to be fast and easy
measurement compared with other conventional analysis techniques. This work is found valuable for
the development of clinical equipment for routine coagulation tests.

10. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976
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