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Low Cost Neonatal Incubator with Smart Control System

Conference Paper · December 2014

DOI: 10.13140/2.1.4591.5201

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 Low Cost Neonatal Incubator with Smart Control
System
Zinat Ara Nisha A.H.M Fazle Elahi
Department of Applied Physics Electronics & Department of Mechanical Engineering
Communication Engineering Khulna University of Engineering & Technology (KUET)
University of Dhaka Khulna-9203, Bangladesh
Dhaka-1000, Bangladesh fazle.elahi.ashek@gmail.com
zinat.ara.nisha@gmail.com

Abstract— A neonatal incubator has been designed, modeled hypothermia, breathing problems, hypoglycemia and even
and developed which is incorporated with embedded death [3-4]. To get to a normal growth premature newborns
temperature and humidity control system. The chamber has two need a warm, clean and salient environment. The newborns
compartments; larger and smaller. Smaller compartment with complications must be put into a Neonatal Intensive Care
consists of temperature and humidity control unit and larger Unit (NICU). NICUs were developed in the 1950s by
compartment consists of a mattress where the baby is kept. The pediatricians to provide better temperature support, isolation
control system components include relative sensors, fans, bulbs, from infection risk and also specialized feeding to newborns.
heater and Arduino Uno microcontroller. For implementation, a [5] The incubators are designed as an isolated area having an
software program has been developed in C which comprises a
infant friendly environment without any dust or parasite and
code editor. A flowchart is provided to illustrate the logical
expression of the program. The salient features of the model are –
has the ability to control environmental factors like temperature
it is entirely microcontroller based, can be locally developed at a and humidity to remain them in acceptable levels such as
low cost and is a sophisticated version of conventional incubator (36°C-37°C) for temperature, (70%-75%) for relative humidity
systems. The system can control the temperature at the set level [6]. Incubator can also be used for full term babies to give
of 36oC to 37oC and relative humidity at the set level of 70% to special medical treatment. Albeit developing countries need the
75%. At the same time the incubator is free of health hazard. It incubator most, many people living there are not capable of
can be used commercially in the hospitals as too at home. affording one. So this project provides a luminous solution for
them. The current recommended method of providing infant
Keywords— Neonatal incubator, Neonatal Intensive Care Unit temperature regulation in resource constrained settings; the
(NICU), Low cost incubator , Smart temperature control, practice of placing newborns directly onto the mother's chest at
Premature Baby, Kangaroo Mother Care (KMC) very low cost.

I. INTRODUCTION II. PHYSIOLOGY

One of the most sensitive concern of biomedical field is the Babies can be categorized according to their gestation
premature infant care. Bangladesh is a developing country and period; Pre term (less than 35 week gestation), Full term (35 to
most of the people here lives around the immediate vicinity of 42 weeks gestation) and Post term (born after 42 weeks
the poverty line. So highly expensive newborn care is not gestation) [7]. Premature babies are those who are born before
affordable for them. But the babies who born 2 or more weeks the pre-term. If an infant born before 31 weeks gestation
before the 38 week gestation badly requires intensive care. evaporative water loss is the main reason to heat loss. It’s
Those infants generally have a net body area greater than because loss of moisture from skin which causes higher
normal babies from same age. [1] That means their body heat permeability. [8]
loss is higher than normal babies. Also these neonates possess
a net weight less than the normal babies which makes them
unable to keep their body temperature to the required level. In
case of premature babies, it is not possible to control their body
temperature without an external aid. In these circumstances
Kangaroo Mother Care (KMC) is certainly effective which
means to hold a preterm baby skin-to-skin with an adult
especially mother. [2] But sometimes KMC could not be
possible for unavoidable reasons. Firstly, if the mother is too ill
after delivery, she won’t be able to provide Kangaroo Mother
Care (KMC). Some of the mothers are helpless because they
may have reasons such as other children or a job or any
ineluctable cause. If providing KMC is not feasible and the Fig. 1. Neutral thermal environment of premature baby
baby is sent home therefore suffer the complications of

978-1-4799-6399-7/14/$31.00 ©2014 IEEE

Having difficulties with heat regulation within the body a two compartments. Larger compartment keeps the baby in and
newborn child can experience an organ failure. [9] Heat may smaller compartment comprises of control units. The control
loss from the body by four ways; Conduction, Evaporation, unit section has three portions. The lower portion is the
Convection and Radiation. Fig.1 illustrates the ways of heat heating unit. Heating unit consists of an incandescent bulb and
loss from an infant body. a 12V dc fan. There are slits on the joining wall of the unit.
The fan exert air flow which becomes heated by the bulb heat
A. Thermoregulation in premature infants and passes through the slit to the baby room. The dc fan and
The temperature inside the mother’s womb is 38oC bulb starts running when the baby room temperature reduces
(100.4oF). [10] After birth, the wet baby finds itself in a much from 37oC and stops when the sensor gives the signal that the
colder environment. So it immediately starts losing heat thus baby room temperature is above 37 oC. The upper portion has
the thermal protection of the newborn is very much important. two subsection. One is cooling unit and the other is humidity
Fig. 2 illustrates the metabolic rate with body temperature of a control unit. Some ice are kept in the cooling unit to reduce
preterm baby and normal range of infant body temperature at the temperature when it goes beyond 37 oC. A 12V dc fan is
which thermo neutrality is achieved. This temperature range is attached outside the cooling chamber to flow the air stream to
very narrow and lies between 36.5oC-37.5°C. Thus, the the baby room in order to confine the temperature within
environmental temperature at which the infant regulates its 37oC. The humidity control unit has the capacity to collect the
body temperature can be considered as the neutral (operative) molten water from the ice of cooling chamber. It contains a
temperature [11].
heater and a 12V dc fan. When humidity sensor sense the
humidity level below 70% this unit automatically starts. It
runs no later than the humidity level reaches at 75%. There is
an exhaust fan on the outside of the baby chamber which
ensures the continuous flow of air. The whole system is
controlled by an Arduino microcontroller program. The supply
current is provided by using transformers, rectifiers, bridge
and relays with 220V AC current.

IV. DESIGN AND CONSTRUCTION

One of the most important elements in a newborn's
survival is the infant’s temperature regulation. The newborn
baby is readily a mature homoeothermic, but the range of
environmental temperature over which an infant can operate
Fig. 2. Heat losses from premature baby successfully is severely restricted. The infant’s body
temperature should be maintained at 36oC-37oC. Another
Thus there is no accurate ambient temperature that is suitable important element is humidity regulation. The dehydration of
for new born babies without considering all factors such as infant with 31 or less weeks of gestation, treaties in ambient
gestation period, body mass, size etc. [12] The new born baby with relative humidity in 20 %, exceed 200 ml/kg/day. To
cannot regulate its temperature like an adult. It therefore cools provide a baby friendly environment the relative humidity
down or heats up much faster and is able to tolerate only a must be maintained within 70% to 75% RH. [16] Keeping in
limited range of temperature. The smaller the new born the mind about the above problems related to the infant we need
greater the risk. Thermal stability improves gradually as baby to design such an incubator system that controls the
increases in weight. [13] As the difference between warm temperature and humidity of the environment where the
womb temperature and the ambient is very high, most of the newborn baby is rested. Fig. 3 shows the block diagram of
heat loss occurs just after the birth of newborn. [14] Incubator total control system unit through which the incubator would
can offer shorter hospitals stay to millions of premature babies run to get optimum temperature and humidity.
and can enable infants who might have faced a lifetime of
severe disability.

III. METHODOLOGY
This project emphasizes on developing an infant incubator
especially for premature babies. Entire chamber of the
incubator is constructed using Acrylic sheet as it is more
advantageous over glass and plastic. This material is less
dense – its density can range from 1100-1200 kg/m3. It is very
much less than the density of glass which ranges 2420 to 2790
kg/m3. [15] Transportation and assembling of acrylic materials Fig. 3. Block diagram of temperature & humidity control system
are consequently easier and cheaper. Main chamber consists of
The Design Requirements of infant incubator are to provide and fans. When the temperature in the chamber falls down
the infant with the bare necessities, these are: (i) An ambient below 36oC the bulb glows and fan associated with the bulb is
temperature of 36⁰C-37⁰C (ii) Humidity greater than 70%RH turned ON so that that the hot air is blown to the compartment
and (iii) sterile air supply. The proposed system of a neonatal B through the slider. The cooling unit consists of an Aluminum
incubator contains following portions:- vessel containing ice and a 12 v dc fan. This fan is connected
with the digital output pin 7 of the Arduino board through a
(a) Structure development of incubator relay. Whenever the temperature in the chamber goes beyond
(b) Temperature control system 37oC the bulb automatically switches off and the fan in the
cooling unit turns ON. Cool air is blown to the compartment B
(c) Humidity control system
until the desired temperature is achieved. Fig. 7 shows the
(d) Control Unit
constructed view of incubator’s temperature controlling unit.
(e) Cost Analysis Fig. 5(a) and 5(b) are heating and cooling portions
A. Structure development of incubator respectively.
It is better that the incubator is light in weight so that it can
be portable at the same time provides strong support for the
components used and can bear the weight of the infant.
Isolation of the compartment where the baby is kept from the
controlling unit is a necessary requirement. The incubator
design can be divided into four subsystems: structural support,
enclosure, shell, and bed. The structural support is the device
that accommodate the other subsystems and the preterm infant.
Design Parameters: Length 80 cm, Height 30 cm, Width 30 cm
thickness of material 5mm. Control unit inside the box has a
dimension of 10 cm x 30 cm x 30 cm. The control unit is 5(a) 5(b)
responsible for holding the heat exchanger and the electrical
components needed for the incubator to work. The shell is Fig. 5. 5(a) Heating unit with incandescent bulb, 5(b) Cooling unit with ice
responsible for retaining the heated air, preventing airborne
infections from reaching the preterm infant, and venting the
C. Humidity Control System
stagnant air. The bed is intended to keep the preterm infant in
place. Fig. 4 depicts the rendered image of the 3D model of At one side of the cooling unit a small compartment is
incubator structure designed by Computer Aided Design. built to serve the purpose of controlling humidity. In this
compartment there is a 100 watt heater and a 12 V dc fan
connected with the digital output pin 6 and 13 respectively.
When the relative humidity falls below 70% the bulb glows.
As a result water is turned into vapor. The fan placed behind
the heater helps to blow the vapors to the small compartment.
If relative humidity exceeds over 75% an exhaust fan placed
outside of the compartment exhausts the air outside of the
incubator. Here the humidity is sensed by the same sensor
DHT11. Fig. 6 depicts the real constructed image of the
incubator humidity control unit. This sensor is so beneficial
because it can render signals for both temperature and
humidity.

Fig. 4. 3D model of the incubator

B. Temperature Control System

The temperature is sensed by DHT11 sensor. It is
connected to the Arduino Uno. In the circuit arrangement of
the control system. Signal pin of the sensor is connected to the
analog input pin A0 of the microcontroller. These are Fig. 6. Constructed view of the incubator with humidity control unit
connected through relays with the digital output pin 10 and 9 of
Arduino board. Each Relays are of 5 volts and are interfaced
D. Control Unit.
with the Arduino Uno through relay drivers. Here NPN
transistors are used as relay drivers. Arduino Uno is the The Arduino Uno is a cross platform application written
controller used here. The program is written to control the bulb in Java, and is derived from the Uno for the Processing
programming language and the Wiring project. For The amounts are in Bangladeshi taka and given according to
implementation, a software program has been developed in C. the particulars used. Cost of the prototype construction is so
It includes a code editor with features such as syntax high less than the commercially available incubator. Thus the
lighting, brace matching, and automatic indentation and is also designed incubator would be available for all at a low cost.
capable of compiling and uploading programs to the board
with a single click. [17] The logical expression for the V. RESULT AND DISCUSSION
program is provided at Fig. 7.
A. Temperature Control Unit
The major concern of this incubator is to control the
temperature of the baby room and maintain it within the
desired range 36oC to 37oC. Fig. 11 exemplifies the process
control by Arduino UNO microcontroller. Here a whole day
(24 hour) data of controlled temperature is inset with the
ambient temperature of the same day.

Fig. 8. Temperature variation in the incubator for control system

At 00:00 am the temperature of atmosphere was low and

almost constant up to morning 6:00 am. Then it rises with the
day time and again lowered at and after 5:00 pm. But the
system for keeping preterm baby safe and sound the
temperature is needed to be constant within the range. The
Fig. 7. Logical expression for Arduino program
incubator constructed has been efficient at doing this and the
graph shows that it kept the temperature of the baby
E. Cost Analysis compartment at 36oC to 37oC irrespective of ambient
The project aims to a cost effective neonatal incubator with temperature.
consistent performance. Total cost of the prototype
B. Humidity Control Unit
construction is enumerated below.
Humidity is another critical factor for preterm infants. Fig.
TABLE I. COST OF CONSTRUCTION FOR INCUBATOR 12 depicts the humidity control by Arduino microcontroller
system and its variation with the ambient humidity.
Product Cost (BDT)
Acrylic sheet 1000
Arduino Uno 1400
Temperature and 750
humidity sensor
LCD display(16×4) 252
Relay(4) 120
12 V dc fans(4) 240
100 W incandescent 60
bulb
Heater 100
Connections and 300
accessories
Total Cost 4222 Fig. 9. Humidity variation of the neonatal incubator and it’s ambient
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