J. Biomedical Science and Engineering, 2011, 4, 769-773
doi:10.4236/jbise.2011.412095 Published Online December 2011 (http://www.SciRP.org/journal/jbise/ JBiSE
Published Online December 2011 in SciRes. http://www.scirp.org/journal/JBiSE
Ovulation detection mechanism—a microcomputer based
Olugbenga K. Ogidan1*, Ayodeji J. Bamisaye2, Olawumi Adetan3
1Information Communications Unit, Ondo State University of Science and Technology (OSUSTECH), Okitipupa, Nigeria;
2Department of Electrical and Electronics Engineering, Federal University of Technology , Akure, Nigeria;
3Department of Electrical and Electronics Engineering, University of Ado Ekiti, Ado Ekiti, Nigeria.
E-mail: *gbengaogidan@yahoo.com, ayobamisaye@ieee.org, wumtay@yahoo.com
Received 8 June 2011; revised 2 August 2011; accepted 9 November 2011.
This paper presents a real-time microcomputer-based
logger for measuring basal body temperature (BBT).
BBT is the normal resting body temperature of a
healthy person immediately upon waking in the
morning. The temperature for women normally rises
after ovulation due to hormonal changes. The tem-
perature is logged real-time into the computer over a
period and the BBT chart produced is used to predict
ovulation. There is high correlation between the ap-
proach developed by this study and other standard
measuring equipments—correlation of 0.9945with
standard thermistor, and correlation of 0.9977 with
standard thermocouple. This development enables
privacy of use, allowing women to predict their ovu-
lation status at a personal level.
Keywords: Basal Body Temperature (BBT); Microcom-
puter-Based Logger, Ovulation, Thermistor, Thermocou-
ple and Correlation
Infertility is the inability of a couple to obtain a clinical
recognizable pregnancy after 12 months of unprotected
intercourse. The alarming rate of infertility among cou-
ples calls for serious efforts and attention from any
woman who is serious about getting pregnant. Most
women, and sometimes their partners, would want to
learn when ovulation and implantation occurs and what
is the best time for intercourse to achieve pregnancy.
Timing the ovulation period is a very important step
towards getting pregnant. With the latest scientific im-
provements, several methods and tests are available for
determining, with a high degree of certainty, when your
ovulation occurs. These include [1,2]:
Calendar Charting/Ovulatio n Calculator: Using this
method, a woman uses her past menstrual cycle as a
guide. This is done by calculating the average number of
days in her cycle, to estimate the future fertile times.
Cervical Mucus Monitoring: In this method, the
cervical fluid is monitored each day.At the beginning of
ovulation, the cervical fluid will go fro m dry or stick y to
creamy like a lotion, and finally will become like egg
white. Many women compare mucus at this stage to raw
egg whites. A woman is most fertile during the egg
white phase.
Cervical Observation: The position of a woman’s
cervix is used to determine ovulation. During and in the
first few days after menstruation, the cervix is fairly low
and firm like the tip of a nose. When the wet cervical
fluid begins to show, the cervix begins to move up, be-
comes more soft, wet and open. During ovulation, the
cervix is at its highest and most open. After ovulation,
the cervix returns to its low, firm and closed position.
Lower Abdominal Discomfort: About one-fifth of
women actually feel ovulatory activity, which can range
from mild achiness to twinges of pain. The condition,
called mittelschmerz, may last a few minutes to a few
hours [3].
Basal Body Temperature (BBT): The basal body
temperature graph is probably the most widely used aid
in the identification of the day of ovulation [4,5] Fol-
lowing ovulation, a woman’s temperature rises by 0.4 to
1.0 degrees and remains up till nex t menstruation p eriod.
This temperature-spike indicates ovulation has o ccurred.
This is because releasing an egg stimulates the produc-
tion of the hormone progesterone, which raises the body
temperature [2, 6]. The body might not feel this shift in
temperature, however with a more sensitive device, it
could be easily detected. This study attempts to develop
a user-friendly, microprocessor-based basal body tem-
perature (BBT) logger capable of detecting and re-
cording the slightest shift in basal body temperature.
This paper is arranged as follows: Section 2 describes
the method, design and theory adopted, Section 3 shows
O. K. Ogidan et al. / J. Biomedical Science and Engineering 4 (2011) 769-773
the performance testing and analysis, while the result
and conclusion drawn are presented in Sections 4 and 5
A simple but sensitive temperature sensory device (called
data-logger) was designed to measure basal body tem-
perature (BBT). The device is portable and battery pow-
ered. This device contains a temperature sensor—ne-
gative temperature coefficient (NTC) thermistor, which
transduces the temperature into electronic analog signal.
The analog signal is then passed into an analog to digital
converter (ADC). The converted signal is then received
and transmitted (using a transceiver) to the microcom-
puter through the parallel port [7]. In the laboratory set-
ting, a personal computer is used. The arrangement is
illustrated in Figure 1. A computer program in Visual
Basic 6.0 was then written to address the parallel port
and to log the data into a user-friendly interface where
the temperature is both interpreted and analyzed. The
circuit diagram is shown in Figure 2, while Figure 3
presents how the device is interfaced with a personal
After, the individual circuit stages and the software
were tested; the assembly was then tested connecting to
a human being (a lady of 21 yr). The temperature was
logged into the computer over a period of time. This was
done also with a mercury thermometer and the readings
were found to be almost the same with a difference of
Temperature sensor
NTC thermistor
Micro Co mputer Interface
Figure 1. Block diagram of a Basal Body Temperature (BBT)
Microcomputer Logger. Let Figure 2 be labelled as Circuit
diagram showing NTC thermistor with a PC parallel port.
igure 2. Circuit diagram.
opyright © 2011 SciRes. JBiSE
O. K. Ogidan et al. / J. Biomedical Science and Engineering 4 (2011) 769-773 771
Figure 3. Diagram of a basal body temperature (BBT) logger
interfaced with a personal computer.
The software was tested and found to be able to:
Measure and log human temperature into the com-
puter real-time;
Start and stop logging automatically and raise an au-
dible alarm or give a visual message when the reading
is beyond a pre-set ( threshold) value.
Give the temperature reading as well as details of the
date, time (minute, second)
It must be noted however that the temperature sensor
would have to be attached to the body under examina-
tion in order to take the reading for a period of time.
In this paper, the temperature measurement device
was calibrated against two known standard digital ther-
mometers using thermistor and thermocouple as sensors.
The correlation with thermistor and thermocouple was
0.9945 and 0.9977 respectively. Therefore, calibration
can be defined as the process of determining the charac-
teristic relationship between the values of the physical
quantity applied to an instrument and the corresponding
positions of the display [6].
Table 1 shows the table of data recorded every 120
The basal body temperature (BBT) measured was logged
into a user-friendly interface that facilitates the viewing,
digital recording and graphical representation of the
measured temperature was presented in Figure 4, any
change (rise or low) in temperature for a specific period
of time can easily be detected and analyzed. The devel-
oped logger was used (at room temperature) to measure
atmospheric temperature alongside standard temperature
sensors (thermistor and thermocouple) for about one
hour(between 8 am and 9 am). The correlation with
thermistor was 0.9945 and 0.9977 with thermocouple.
The results tend to unity thus showing a high degree of
measurement reliability. Figure 5 shows the graph of the
igure 4. User-friendly interface showing graphical representation of temperature measured by the logger.
opyright © 2011 SciRes. JBiSE
O. K. Ogidan et al. / J. Biomedical Science and Engineering 4 (2011) 769-773
Table 1. Data recorded every 120 seconds from 8 am to 9 am
using standard thermistor, standard thermocouple and Devel-
oped data logger.
Time (secs)
8 am - 9 am Develop Standar d TH Standar d TH C
120 25.62 25.69 25.67
240 27.54 27.58 27.55
360 27.60 27.64 27.55
480 27.68 27.58 27.68
600 27.72 27.60 27.55
720 27.72 27.60 27.55
840 28.71 28.60 28.67
960 28.50 28.55 28.50
1080 28.44 28.55 28.50
1200 28.50 28.55 28.50
1320 28.52 28.55 28.50
1440 28.66 28.63 28.67
1560 28.88 28.71 28.84
1680 28.60 28.63 28.66
1800 28.82 28.71 28.84
1920 28.66 28.63 28.67
2040 28.66 28.63 28.67
2160 28.60 28.63 28.66
2280 28.84 28.71 28.84
2400 28.66 28.63 28.67
2520 28.62 28.63 28.66
2640 28.86 28.71 28.84
2760 28.44 28.55 28.50
2880 28.64 28.62 28.65
3000 28.46 28.55 28.50
3120 28.66 28.63 28.67
3240 28.64 28.62 28.65
3360 28.66 28.63 28.66
3480 28.64 28.62 28.65
3600 28.66 28.63 28.67
Correlation with develop
thermometer 0.9945748 0.997785
Figure 5. Graph of developed BBT logger compared with
standard thermistor and thermocouple when used to measure
atmospheric t e mperature.
This study has developed a Basal Body Temperature
(BBT) logging system, which makes fertility charting
very easy. The system has been calibrated and is being
put to clinical use. The developed logger compares fa-
vourably with standard thermistor with a correlation of
0.9945, and with standard thermocouple with a correla-
tion of 0.9977. This device has many advantages in-
cluding enabling privacy, provides non-intrusive method
of ovulation detection; provides data easily to physicians
which could be interpreted for diagnosis and treatment
of their patients; and has a good potential for telemedi-
The researchers acknowledge Prof. M.O Kolawole and Dr V.S.A
Adeloye for their immense assistance and contribution and also The
Federal University of Technology, Akure, Nigeria.
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