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Effect of Ambient Temperature Variations on Particle Dimesions in Ultrasonic Nebulizers during Cold
Vaporization
Ali Akpek*
Department of Bioengineering, Gebze Technical University, 44100, Turkey
A R T I C L E I N F O
A B S T R A C T
Article history:
Received: 30 April, 2017
Accepted: 11 June, 2017
Online: 30 June, 2017
For human comfort and convenience, appropriate temperature values may not be sufficient
enough for the environment that they live in. The moisture content of the air has an
important place in this regard. 30% to 65% humidity is desireable for a relaxed and
comfortable life. Humidity in the environment is fundamental for the human health,
convenience and comfort. Humidity is also valid for therapeutics. The drugs that are used
in medicine for diagnosis and therapy must be inhaled with cold or hot water vapor in case
drug effectiveness is desired to be increased. For such achievments, cold vaporization
method is being preferred to reach the alveoli of the patients, thus, the drug can be used in
a more efficient manner without damaging the respiratory tract. In this project, effect of
ambient temperaure in ultrasonic nebulizers is investigated. It is proved that as the
temperature increases 5°C, the speed of cold vapor increases 10% which refers a decrease
in particle diameter. The variations in particle dimension may severely effect the efficiency
of therapeutics. Therefore, in this study, it is presented that ultrasonic nebulizers should be
designed considering ambient temperature. A design rationale is proposed in this study.
Keywords:
Ultrasonic nebulizer
Particle dimension
Cold vaporization
1. Introduction
For the human comfort and convenience, only appropriate
temperature values may not be sufficient for the environment that
they live in. The moisture content of the air has an important place
in this regard [2]. For a relaxed and comfortable life relative
humidity is desirable in the range of %30 to %65 in the
environment [3]. Humidity in the environment is fundamental for
the human health, convenience and comfort [4]. The drugs that
used in medicine for diagnosis and therapy must be inhaled with
both cold and hot water vapor steam in the patient's body [5]. Cold
vaporization method is being preferred to reach the alveoli of the
patient, thus, the drug can be used in a more efficient manner
without damaging the respiratory tract [6].
Ultrasonic nebulizers utilize water to carry out drugs to the
alveols. Ultrasonic nebulizers dissociate water into their smallest
particles by sound waves and thus compose cold vapour. Obtained
cold vapour and drugs are mixed intoeach other and blown to
patient through a mask or directly to the environment. Therefore,
respiratory tract is moisturized and the desired drugs are carried
out to the alveols of the patients efficiently [7].
Some environments may contain excessive moisture while
some of them are over dried. This situation is pretty much
common especially among the houses with a radiator during
winters and houses with air conditioning in summers. Ideal
moisture ratio should be between 30% and 65% for human beings.
For humans especially for babies, dry air may cause enfections to
spread faster, dehydrate pharyngonasal area, burning in the eyes
and cracking in the lips. Dust formation becomes rapid and affects
those with allergies. [8]. The spread of cold vapor provides
accurate humidity in the environment and creates beneficial
effects on health. Water droplets have ionizing effect for the air.
Negative ions attack pollutant particles in the air, reducing it to a
minimum, thereby reducing cigarette smoke, pollens and dust [9].
Medical studies have proved that negative ions have a positive
effect on people's physical and psychological health with both
their stress-relief functions and their direct effects on respiratory
devices which makes them much more effective [10].
ASTESJ
ISSN: 2415-6698
*Corresponding Author: Ali Akpek, Department of Bioengineering, Gebze
Technical University, 44100, Turkey | Email: aliakpek@mit.edu
Advances in Science, Technology and Engineering Systems Journal Vol. 2, No. 3, 946-950 (2017)
www.astesj.com
Special Issue on Recent Advances in Engineering Systems
A. Akpek / Advances in Science, Technology and Engineering Systems Journal Vol. 2, No. 3, 946-950 (2017)
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Simply a nebulizer generates vapour. There are various ways
to generate vapour [11]. The most convenient method for this is
by heating the liquid. On the other hand an ultrasonic nebulizer
system evaporates liquids with ultrasonic sound waves. The major
problem here is not evaporating water but obtaining cold vapour.
An ultrasonic nebulizer uses a vibrating piezoelectric crystal
that vibrates with 1.7 MHz or higher frequency in order to
generate vapour [12]. The crystal transducer is made of materials
like quartz-barium titanate and converts electrical signals into
sound waves. The sound beam that focuses on the liquid which is
located just above the transducer creates waves. When the
frequency and amplitude are strong enough, the wave peak
reaches the surface of the fluid as a sprinkler of water particles.
Working principle of an ultrasonic nebulizer is illustrated in
Fig. 1
.
Ultrasonic nebulizers are most frequently used in intensive
care units. In these units, ultrasonic nebulizers are mainly used for
the humidification of the rooms, and also for the evaporation of
liquid medicines to assist them to effectively inhaled by
respiratory organs. In addition, it is also used to humidify the air
for patients who are connected to artificial respiration and oxygen
support systems [13].
By the help of this study, effect of ambient temperature on
ultrasonic nebulizers is investigated. In order to achieve this,
ambient temperature is constantly recorded and particle
dimensions of cold vapour are measured. As a result it is
understood that, ambient temperature has a serious impact on
particle dimension thus affecting the effectiveness of ultrasonic
nebulizers therapeutic capability.
In addition, this study aims to further development of national
fabrication of ultrasonic nebulizers in Turkey and creates
difference in the area of biomedical device fabrication that may
not be evaluated as strong [14-22].
2. Materials and Method
Ultrasonic nebulizers are based on the princible that
disassociating water into its particles with high frequency sound
waves that is generated by a vibrating piezoelectric crystal. This
piezoelectric crystal that is located under the liquid, generate
sound waves with a frequency of 1.7 MHz or more, and
disassociating water into its particles.
It is possible to change the particle diameter of of the
evaporation by changing the frequency of the piezoelectric
crystal. As the frequency of the piezoelectric crystal increases, the
particle diameter decreases. As the frequency decreases, the
particle diameter increases. As the particle diameter increases, it
will be unable for medications or humid air to reach the extreme
edges of the alveoli. Same phenomenon is observed when the
ambient temperature changes. Particle size decreases as the
ambient temperature increases, while particle sizes increase as the
ambient temperature decreases.
The quantity of the liquid is important since the piezoelectric
crystal is operated inside the liquid. It is important because crystal
may deteriorate due to the heat energy that occurs during the
formation of the sound waves. For this reason, the quantity of the
water is constantly measured and a system is designed that
prevents the degradation of the crystal by cutting the energy when
there is not enough water left within the device.
Block diagram of the designed ultrasonic nebülizer is
illustrated in Fig. 2. A picture of the ultrasonic crystal is presented
in Fig. 3. In addition, a level sensor for water measurement is
shown in Fig 5.
Fig. 1: Working principle of an ultrasonic nebülizer
Fig. 2: Block diagram of the designed ultrasonic nebülizer
Fig. 3: Ultrasonic crystal
A. Akpek / Advances in Science, Technology and Engineering Systems Journal Vol. 2, No. 3, 946-950 (2017)
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The design and drawing stages of the nebulizer circuit were
first completed using the Proteus ISIS program. The design is
simulated with the Proteus ISIS program to check the operability
of the system. After being confident that the simulation process of
the design is completed and the design may work flawlessly, the
process of printing circuit board with Proteus ARES program is
started. This process is presented in Fig. 6.
The design of the boxing process has initiated after the
control of the nebulizer circuit and date/clock circuit are
implemented and operability of the design is controled. Therefore
the circuit and system could be used in maximum confort.
A crystal with a special casting design is placed in the lower
part of the water tank. BU 406 power transistor that controls the
ultrasonic crystal generates a lot of heat due to the high voltage
and fast triggering characteristics. Since this heat may damage the
transistor, the special casting that surrounds the crystal is used as
a cooler. The water within the water tank cools down the casting
and casting cools the crystal and the transistor. This is the reason
why water level is critically important for this research. The cold
vapor that is generated by the crystal is delivered to the patient by
the help of a channel just located on the top of the ultrasonic
nebulizer.
Finally, chassis is placed and LCD screen that displays
ambient temperature, date/time and control parameters is located
on it. Therefore the prototype is finalized. LCD screen and the
final design of the ultrasonic nebulizer are shown in
Figs. 7, 8 and 9.
The experiments are done by changing the ambient
temperatures by several radiators that surrounds the ultrasonic
nebulizer. At the beginnig the temperature is recorded as 25ºC
±0.3ºC. The process is initiated and the period until the visually
detection of cold vapor out from the funnel of the nebulizer is
recorded. This period provides the speed of the particles of cold
vapor thus giving us the estimations for particle dimensions.
As second step the temperature is increased 5ºC to 30ºC ±
0.3ºC, the process is initiated and the period of visually detection
of cold vapour is recorded. As third step the temperature is
increased to 35ºC and the entire process is recorded again. As
fourth and fifth step, the temperature is reduced to 20ºC ± 0.3ºC
and 15ºC ± 0.3ºC, respectively. In those steps, period of visually
detection of cold vapor is recorded. All steps are repeated three
times to obtain statistically accurate results.
3. Results and Discussion
During the test phase, the ambient temperature is measured
in different methods and double checked to ensure that the sensor
and system operate properly and consistently. In order to ensure
the system has taken correct measurements or not, the
measurement stability was controlled with a calibrated
thermometer at regular intervals.
Fig.4 presents the relationship between ambient temperature
change and period for visually detection of cold vapor. As it is
shown as the temperature increases the vapor speed decreases
which refers an increase in particle dimensions.
Fig. 4: The relationship between ambient temperature change and period for
visually detection of cold vapor.
Fig. 5: Level sensor for water measurement
Fig. 6: Designing the circuit board of an ultrasonic nebulizer
A. Akpek / Advances in Science, Technology and Engineering Systems Journal Vol. 2, No. 3, 946-950 (2017)
www.astesj.com 949
Fig 7: Temperature measurement results a) 25ºC b)-11.3ºC c) +62.2 ºC
Fig. 8: Inside and back views of the designed ultrasonic nebulizer
Fig. 9: Final prototype of ultrasonic nebulizer b) During work
4. Conclusion
The purpose of this project is to prove that it is quite simple
to fabricate home made low cost specially designed ultrasonic
nebulizers that is mainly imported to Turkey with high prices.
In addition, it is proved that ambient temperature has serious
impact on particle dimensions. It is presented that as the ambient
temperature increases five celcius, the speed of cold vapour
increases around 10% which refers a decrease in particle
dimensions. As the temperature decreases five celcius, the speed
of cold vapor also decreases 10% which refers an increase in
particle dimensions.
As future researches, Particle Image Velocimetry (PIV)
might be used to understand the particle dimensions in detail. A
PIV may assist us to truly analysis the particle speed and
dimensions of the cold vapor as the temperature increases or
decreases. Also, in future the sensitivity of the research might be
increased, therefore change in particle dimensions and particle
speed per one celcius temperature variation might be detected.
This may help us to optimize the period for therapeutics.
The most important innovation in this study is to merge a
temperature sensor just outside the cover of the ultrasonic
nebulizer. This assists users to estimate the particle dimensions
and predict the optimum time for therapeutic.
In future, an ultrasonic nebulizer that adjusts the vibration
frequency of the ultrasonic crystal based on the change in ambient
temperature might be designed. This design may optimize the
dimensions of particles and fix the period for therapeutic. This
version of an ultrasonic nebulizer will prevent the fluctiations
caused by temperature variations of the environment.
This model of an ultrasonic nebulizer is yet haven’t
fabricated. This should be considered as a future direction.
Conflict of Interest
The authors declare no conflict of interest.
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