NeoCrib Incubator
-produced by Paul Lee and Fabio Raman
This is the prototype design of our product that can regulate the internal temperature and relative humidity.
Device Need
The Premature Newborn Cabinet is a device meant to regulate the temperature and humidity for infants born prematurely so that they can grow and be nourished in a completely regulated local environment. Premature, or preterm, births are usually associated with infants born before 37 weeks gestational period. Premature babies are more likely than babies born in the normal gestational period (37 to 41 weeks) to suffer long-term complications as well as face early morbidity, or even death (National Vital Statistics Reports, 2010). Within the normal term babies, statistics have shown that early-term infants (37 to 38 weeks) have a higher rate of morbidity than full term infants (39 to 41 weeks). Thus, this device is necessary to help premature and early-term infants survive until their bodies and organs have developed enough to withstand normal external environmental conditions.
Around 12.3% of all babies, or 518,322 infants, were born prematurely in the United States in 2008 according to the latest full report released by the National Center for Health Statistics (NCHS) (National Vital Statistics Reports, 2010). Of this number, 8.77% were born between 34 to 36 weeks (gestational period) and 3.56% under 34 weeks. This total number, 12.3%, is actual a gradual decrease in number of premature newborns from the previous 2 years as 12.68% were born prematurely in 2007 and 12.80% in 2006. However, the relatively large amount of premature infants in 2008 coupled with another 27.85% of babies born in the early-term period in 2008 shows that the target market is still large to current date. Although the usefulness of an incubator for babies born in the early-term period depends on a case-to-case basis, babies born prematurely would need some sort of incubator to greatly increase their chances of survival and minimize the chances of health complications.
Thus, the device should be targeted towards both early-term and pre-term newborns by selling the device to pediatricians in top-tier children’s hospitals in United States. This method would be more effective than targeting the parents of the newborns directly as hospitals need to be equipped with the technology before patients can even use the new device. Additionally, patients usually hear about breakthrough technology through their physicians. Implementation of a medical device in the mainstream market is usually based on a doctor’s acceptance and faith in the new technology. Thus, the premature newborn cabinet should first be targeted to doctors in the top three children’s hospitals, or the Children’s Hospital of Philadelphia (CHOP), the Children’s Hospital of Boston, and Texas Children’s Hospital. These “innovators” in the market are not only full of early adopters and leaders in their field but also the hospitals have beneficial connections to insurance companies, which will help make the product even more affordable to the buyers. Once the main hospitals adopt our Premature Newborn Cabinet, other hospitals will likely follow in adopting the same breakthrough technology.
Competitive Products
Most of the current neonatal incubators are doubled walled close type incubators that administer servo controlled oxygen, humidity, and air temperature to maintain the ambient temperature in the cabinet and to provide the desired humidity and oxygenation. The entire incubator unit utilizes microprocessor-based systems to create and maintain the ideal microclimate for the neonate. Skin senor is affixed to the abdomen part of the baby and sends information regarding skin temperature to the thermostat, which controls the output to the heat fan for cabinet temperature regulation. In addition to the skin sensor, other devices included are an AC-powered heater, a fan to circulate the warm air, a container for water to add humidity, a control valve through which oxygen may be added, and access ports for nursing care. When microclimate conditions are not maintained, built in audio alarm will sound to alert staff members.
One novel device is the Ohmeda Giraffe OmniBed that built by GE Healthcare. This device has the thermal advantages of a double-walled incubator with the access advantages of an open bed radiant warmer. By combing an incubator and a radiator into one, OmniBed reduces the necessity of transferring the patient during extensive procedures and during continual access to the infant. OmniBed operates in either the incubator or the radiant warmer mode, but never as both simultaneously. In incubator mode, it has air temperature and baby skin temperature control and integral humificiation. All control settings are integrated into a microprocessor, which allows users for easy settings control. Heating is uniform in cabinet regardless of baby position and mattress is evenly heated to minimize heat loss due to conduction. Humidity can be controlled between the ranges of 30% to 95% RH in 5% increments. Preset cabinet temperature maintains temperature between 35C to 37.5 C. Its general advantages are the combination of incubator and radiant warmer in one device and a swivel mattress for ease of access. A swivel mattress is designed for easier access and handling of neonates. It allows 360 degree rotation and can also be free tilted to any angle up to 12 degree in either the feet-up or head-up direction when inside the baby compartment. OmniBed’s main disadvantage is that it costs $35,000, and is relatively more expensive than other non-portable hospital incubators, which are around $20,000 per unit. However, even at a price of $20,000 per unit, hospital-grade incubators are too expensive to be purchased by third world country hospitals. Another disadvantage is that water reservoirs used for humidity control in these incubators are susceptible to bacterial growth. Lastly, incubator temperature can fluctuate when infant care is delivered.
Other Competitive Products in the Market
Product: Intensive Care Neonatal Transport Incubator, INC-100
Description of product: These neonatal incubators are designed to provide the safest and most stable environment for the neonate. Offered with a wide range of accessories, the neonatal incubators can be tailored to meet any critical situation arising in providing care.
Company: Phoenix Medical Systems
Summary of company: Company sells a lot of neonatal, maternal, and healthcare equipment. They offer the following products:
Advantages:
· Excellent access
· Safe and reliable operation
· Ease of cleaning
· Sturdy construction
· FDA approved
· Have been accredited with USFDA and CE certifications
Disadvantages
Relatively large device, intended primarily for hospitals
Product: Ohmeda Giraffe OmniBed (Neonatal Incubator/Infant Radiant Warmer)
Description of product: A novel device combining an incubator and a radiant warmer in one unit. The transformation from an incubator to a radiant warmer is activated by the touch of a switch. All the usual features of an incubator and radiant warmer are included. In addition the mattress swivels.
Company: Ohmeda Medical
Company description: sells all types of medical/healthcare equipment. A lot of their products are related to air control and anesthesia. They sell pulse oximiters, CO2 monitors, infant medical furniture, medical air and vacuum pumping systems, etc.
Advantages: Incubator and infant radiant warmer in one device. Relative humidity
option, swivel mattress, all around access, uniform central thermal environment.
Disadvantages: Care needed on raising canopy to avoid collisions with other equipment close by. Expensive. Water reservoir difficult to open.
Product: Neonatal incubators and Transport Incubators
Company: Ducray Lenoir Ltd
Description: They sell products in all of the following categories:
They sell all of this neonatal equipment:
Advantages: Offer a wider array of neonatal products, including both a transportable and non-transportable incubator.
Disadvantages: Incubator lacks some of the special amenities that other incubators have.
Product: Thermocare Vita Neonatal Incubator
Description: Intensive care of pre-term or sick babies should not only secure the survival. Also devotion and comfort must be given to the baby in order to make life possible.
The incubator - Vita, will help you to achieve this purpose.
It conjoins the stability of a closed ambience with the good access and contact possibilities offered by open care systems.
Company: Thermocare (sold by Central Medical Supplies)
Company description: sells products for vetininary purposes as well, such as animal intensive care units.
Advantages:
Ergonomic design
The perspex double-wall assembly has four ports. For quick access all walls can be folded down with one hand, the canopy can be removed easily. For passing tubes and cables sufficient grommets are provided. For taking x-ray it is not necessary to open the wall assembly, the tray for the cassette is inserted from the outside. Of course, for special procedures the bed can be pulled out completely. The incubator is also available with an integrated weighingscale. There is an electromotive bed tilt in both directions with automatic stop in weighing position. The desired working height can be adjusted by foot pedal.
Storage space and choice of accessories
A large shelf and two drawers are provided for storing material necessary for treatment. The accessories from the Thermocare and Variotherm devices are compatible and can be fixed at the rails and the spar assembly.
The control module
Innovative technology controls and monitors the selected values for air and patient temperature as well as for humidity and oxygen concentration. The selected parameters and measured values are indicated clearly structured with a graphic display of the development during the last three hours.
All values can be retraced and evaluated for the period of one week.
Reverse Engineering
The Dual Incubator Temperature Control System was developed by Ohmeda Healthcare in 1998 and was later acquired by G.E Healthcare. The details of this invention are described in patent #6036633. It is an infant incubator that provides a flow of heated air into the infant compartment and which exhausts air from the infant compartment. It consists of two thermometers that are placed in the inflow and outflow of the compartment to carry out the control and monitoring of the heating system that supplies the warm air to the infant compartment. By use of air temperature sensors in the two selected locations, information on air temperature within infant compartment and existence of fault in the fan or heater system can be detected.
Heating of the compartment consists of a conventional heater and a fan that induces the air past heater to heat the air which then enters the remaining part of the heater compartment. A fan is used to provide circulation of the heated air. The heated air then circulates the whole compartment and enters the air outlet. Air that enters the outlet would be slightly cooled than air that enters the inlet. Temperature sensors that measured the temperature difference of heated air in and out provide a sense of heat transferred to infant compartment to warm the infant. A CPU can then calculate and determine the air temperature within the compartment and can then use that derived temperature to regulate heater control or speed of fan to provide the desired amount of heat to the infant compartment. An abnormal condition can be detected as such the temperature in the inlet incases but the temperature in the outlet does not follow that increase in temperature, which can indicate that warm air is escaping outside the infant cabinet. When an abnormal condition such as the scenario previously described is sensed by the two temperature sensors, an alarm would sound and notify the user of such fault condition.
GE Healthcare is a unit of GE technology Infrastructure. It generates around 10% of G.E’s total revenue, which is approximately $17 billion dollars. Its major competitors include Hitachi Medical systems, Philips Healthcare, Siemens Healthcare, and Toshiba Medical Systems. It offers services in medical imaging, information technologies, medical diagnostics, patient monitoring systems, and biopharmaceutical manufacturing. Neonatal incubators are part of the patient monitoring segment. G. E Healthcare is also known to partake in many humanitarian missions in distributing medical equipment to third world country. In December 2010, G. E partnered with Embrace, a nonprofit based group to distribute low cost infant warming sleeping bag in an effort to promote awareness of infant mortality. The infant warming sleeping bag costs around $200 and are 100 times cheaper than hospital-grade incubators, are reusable and can maintain a consistence 98.6 degrees Fahrenheit for 4 hours without electricity.
Device Specifications
Conceptual Design of Device
If our device was up-scaled to the appropriate proportions to accommodate a premature infant, our device did meet the most basic specifications necessary to provide adequate environmental control and safety for a newborn child. The device in our demo effectively maintained a constant, consistent temperature between 27ºC and 29ºC as well as a relative humidity between 55% and 60%. Thus, both the code and hardware functioned effectively in regulating the local environment of our downscaled prenatal incubator. Furthermore, our device also displayed the temperature and humidity readouts on a serial monitor to allow the physician to perform quality control, ensuring that the temperature was being regulated effectively.
However, in order for our device to applied in a professional medical setting, several of the components would have to be up-scaled to meet proper medical safety standards. For instance, our device contained a heat/humidity source that ensured that the air within the compartment would never get too dry or cold. The hot water mug used in the demo would simply have to be replaced by an adequate humidifier and heat source. Similarly, the fan that worked effectively in the demo to cool the small compartment would have to be replaced by a more powerful, high-powered fan to cool a life-size baby incubator. The buzzer on the arduino should also be replaced by a louder alarm that could signal physicians farther away from the device. If each of these weakness were addressed, the device would be able to perform effectively in a medical setting.
In addition to the components provided in the device, we would make the incubator battery powered to make the device transportable. Thus, the device could be easily moved around the hospital. Additionally, the device could be transported in a vehicle to another hospital or a house if needed. In addition to the device being battery powered, the device could contain a blue-tooth device that could transmit the humidity and temperature readings to a cellular phone. Thus, the physician would could be alerted away from the room where the device was situated when the temperature or humidity rose above the threshold. Finally, an LCD readout could be present on the actual device itself, so the humidity and temperature could be read while the device is being transported.
Functional Block Diagram
The Arduino microcontroller is connected to both the humidity and temperature sensor as well as the fan and buzzer.
Proof of Concept/Functional Prototype of Device
The device functions by placing a continuous heat and humidity source within the chamber, which was built from a cardboard box. In the case of this project, a mug containing hot water was used this heat/humidity source. On the external sides of the box, two holes were cut: one for the fan and the other for the air exhaust, which was placed directly opposite the fan for maximum cooling efficiency. The arduino microcontroller, which contained both the humidity and temperature sensor as well as the buzzer, was placed inside the box. Basically, the temperature and humidity sensors would both receive input information and display readouts on the serial monitor of the PC connected to the arduino. A threshold value of (28ºC and 65% relative humidity) was set in the code within an if/else loop. If the temperature or relative humidity went above this threshold, the fan and buzzer would turn on. The buzzer would emit a series of short beeps continuously until the fan has cooled the device below this threshold. Then, both the fan and buzzer would turn off simultaneously. The buzzer was turned off by inserting a non-existent input pin number for the buzzer under the “else” part of the loop (the “else” part of the loop represented the temperature and relative humidity values below the threshold). The fan was turned off by simply switching the state from “HIGH” to “LOW.”
The DS1620 Digital Thermometer was used as our temperature sensor. The DS1620 had to be connected to the ground and 5V source on the arduino as well as three separate pins denoted as RST, CLK, and DQ, which were connected to pins 3, 4, and 5, respectively. All three of these pins were used to transmit data. RST referred to the “reset” input pin. Setting RST to high initiated all the data transfers for this part of the code. The DQ input/output pin was used to send/receive the 8-bit data commands. Meanwhile, the DQ could be jammed on high to be used as an input or set on low to be used as an output. The CLK input pin was used for clock pulses.
The HIH-430 Humidity Sensor was an analog humidity sensor connected to the ground and one of the analog inputs. The humidity sensor worked by continuously reading a voltage gradient on the analog input. The analogRead() function converted the voltage received through the humidity sensor to a digital value between 0 and 1023 where 0 represented 0 volts and 1023 represented the maximum 5 V of the arduino. Basically, the voltage would increase as resistance decreased in the humidity sensor. Increasing humidity would trigger lower resistance in the sensor. This would increase the voltage at the analog input. The analogRead() function then converted this value to a digital number. As relative humidity depends on the external temperature, a linear function was used to convert this value, based on the voltage, to the relative humidity, factoring in the temperature reading from the DS1620 Digital Thermometer Sensor. Due to the presence of this temperature sensor, an accurate reading of the relative humidity was able to be made using the sensor’s linear relationship of voltage to relative humidity.
These images show the fan switching between the “off”(left) and “on” (right) state. The fan switches to the “on” state when the temperature or relative humidity threshold is reached. The fan then turns off once the desired internal climate is reached.
Additional Information
If our device was up-scaled to the appropriate proportions to accommodate a premature infant, our device did meet the most basic specifications necessary to provide adequate environmental control and safety for a newborn child. The device in our demo effectively maintained a constant, consistent temperature between 27ºC and 29ºC as well as a relative humidity between 55% and 60%. Thus, both the code and hardware functioned effectively in regulating the local environment of our downscaled prenatal incubator. Furthermore, our device also displayed the temperature and humidity readouts on a serial monitor to allow the physician to perform quality control, ensuring that the temperature was being regulated effectively. Also, the alarm system helped to ensure the safety of the infant in the incubator as the pediatrician would be alerted each time that the device temperature or humidity went above the threshold.
However, in order for our device to applied in a professional medical setting, several of the components would have to be up-scaled to meet proper medical safety standards. For instance, our device contained a heat/humidity source that ensured that the air within the compartment would never get too dry or cold. The hot water mug used in the demo would simply have to be replaced by an adequate humidifier and heat source. Similarly, the fan that worked effectively in the demo to cool the small compartment would have to be replaced by a more powerful, high-powered fan to cool a life-size baby incubator. The buzzer on the arduino should also be replaced by a louder alarm that could signal physicians farther away from the device. If each of these equipment-related weaknesses in the demo were addressed, the device would be able to perform effectively in a medical setting.
In addition to the components provided in the device, we would make the incubator battery-powered to make the device transportable. Thus, the device could be easily moved around the hospital. Additionally, the device could be transported in a vehicle to another hospital or a house if needed. In addition to the device being battery powered, the device could contain a blue-tooth device that could transmit the humidity and temperature readings to a cellular phone. Thus, the physician could be alerted away from the room where the device was situated. Finally, an
LCD readout could be present on the actual device itself, so the humidity and temperature could be read while the device is being transported.
This image displays the serial monitor that reads the temperature and relative humidity ever second. Additionally, this image shows the glitch that occurs each time there is a rapid change in current due to the fan turning on and off.
Finally, the main weakness in the NeoCrib Incubator prototype that we would have to address is the rapid change in current when the fan turns on that causes a glitch in the serial monitor. This phenomenon can be explained by the loading effect. Basically, in order to achieve a stable output voltage, the output current should be a small fraction of the input current. Basically, the gain should be small, meaning the ratio of current going into circuit should be small compared to current going to the fan as an output. In the case of our prototype, the rapid change in current when the fan turned off and on caused a glitch as the gain was really high as the output current was fairly high compared to the input current. This problem can be fixed by amplifying the input current to make it much higher than the output current. One specific technology that can do this are the L293 and L293D, which are quadruple high-current half-H drivers. These devices amplify the input current and make the gain smaller.
Code:
#include <SoftwareSerial.h>
#define rxPin 0
#define txPin 1
#define ledPin 13
#define buttonPin 2
#define rstPin 3
#define clkPin 4
#define dqPin 5
int motorPin = 8;
float val = 3;
float RH = 3;
float my_room_temperature = 20; //in degrees C !
float max_voltage = 3.27;
// set up a new serial port
SoftwareSerial mySerial = SoftwareSerial(rxPin, txPin);
byte pinState = 0;
void setup() {
// define pin modes for tx, rx, led pins:
pinMode(rxPin, INPUT);
pinMode(txPin, OUTPUT);
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);
pinMode(rstPin, OUTPUT);
pinMode(clkPin, OUTPUT);
pinMode(dqPin, OUTPUT);
pinMode(motorPin, OUTPUT);
pinMode(11,OUTPUT);
digitalWrite(motorPin, LOW);
// set the data rate for the SoftwareSerial port
mySerial.begin(9600);
}
void loop() {
val = analogRead(3);
delay(500);
my_room_temperature = 20; // If you have temperature reading, put it here (centigrade!)
max_voltage = (3.27-(0.006706*my_room_temperature)) ; // The max voltage value drops down 0.006705882 for each degree C over 0C. The voltage at 0C is 3.27 (corrected for zero precent voltage)
RH = ((((val/1023)*5)-0.585)/max_voltage)*100;
Serial.println(RH);
int val = digitalRead(buttonPin);
rst_low();
clk_high();
rst_high(); //all data transfer are initiated by driving RST high
write_command(0x0c); // write config command
write_command(0x02); // cpu mode
rst_low();
delay(200); //wait until the configuration register is written
clk_high();
rst_high();
write_command(0xEE); //start conversion
rst_low();
delay(200);
clk_high();
rst_high();
write_command(0xAA);
int raw_data = read_raw_data();
rst_low();
int humidity = RH;
mySerial.print("temperature:");
mySerial.print(raw_data/2);
mySerial.println(" C");
mySerial.print("Humidity:");
mySerial.print(humidity);
mySerial.println(".");
if (RH > 65|| raw_data/2 > 28) {
digitalWrite(motorPin,HIGH);
tone(11,8000,100);
}
else {
digitalWrite(motorPin,LOW);
tone(12,8000,2000);
}
delay(100);
// toggle an LED just so you see the thing's alive.
toggle(13);
}
void toggle(int pinNum) {
// set the LED pin using the pinState variable:
digitalWrite(pinNum, pinState);
// if pinState = 0, set it to 1, and vice versa:
pinState = !pinState;
}
void write_command(int command)
/* sends 8 bit command on DQ output, least sig bit first */
{
int n, bit;
for(n=0;n<8;n++)
{
bit = ((command >> n) & (0x01));
out_bit(bit);
}
}
int read_raw_data(void)
{
int bit,n;
int raw_data=0;
pinMode(dqPin,INPUT);
/* jam the dq lead high to use as input */
for(n=0;n<9;n++)
{
clk_low();
bit=(digitalRead(dqPin));
clk_high();
raw_data = raw_data | (bit << n);
}
pinMode(dqPin, OUTPUT);
return(raw_data);
}
void out_bit(int bit)
{
digitalWrite(dqPin, bit); /* set up the data */
clk_low(); /* and then provide a clock pulse */
clk_high();
}
void clk_high(void)
{
digitalWrite(clkPin,HIGH);
}
void clk_low(void)
{
digitalWrite(clkPin,LOW);
}
void rst_high(void)
{
digitalWrite(rstPin,HIGH);
}
void rst_low(void)
{
digitalWrite(rstPin,LOW);
}
References
Hodge, C.G. (14 March, 2010). Dual Incubator Temperature Control System. United States Patent for Infant Incubator.
Martin, J. A., et. al. (December, 2010). National Vital Statistics Reports. National Center for Health Statistics: 59 (1).
TexasInstruments (2002). L293D Motor Driver Datasheet.
