We wanted to focus on creating a system to maintain healthy breathing for firefighters. Lack of oxygen causes an increased heart rate which can cause cardiac arrest or suffocation. We went through many iterations throughout this process to decide which element of breathing we wanted to focus on.
Iteration 1: oxygen saturation/ hypoxia: lack of oxygen to the brain (we wanted to measure the oxygen levels in their blood) this was a clip onto the finger/ ear so that they light could shine through
We talked to firefighter and he said that since the oxygen tanks they use monitor their oxygen levels already, hydrogen cyanide is more of an issue. He described how after they would put out the fire there are usually still toxic gases in the air.
Iteration 2: Hydrogen Cyanide is a form of histotoxic hypoxia. Hydrogen Cyanide poisoning is one of the leading causes of death for firefighters. Hydrogen Cyanide results from burning polymer products that use Nitrile in their production; for example, vinyl. Hydrogen Cyanide poisoning most often occurs after the fire is extinguished and there are still toxic chemicals in the air. After the firefighters are done extinguishing, they will often take off their masks and safety gear, which makes them at risk for Cyanide Poisoning. Depending on the dosage of Hydrogen Cyanide in the air, inhaling a few breaths of this toxic gas, can result in death within minutes. It's like carbon monoxide poisoning, but much faster and more deadly. (firefighters frequently inhale toxic gases that linger in the air after a fire has been put out, they're at risk once they take their safety gear off often during the cleanup process) It 3 times more powerful than carbon monoxide when bonding to the hemoglobin. (the hemoglobin is the protein molecule in red blood cells that transfers oxygen from the lungs to the body's tissues and then returns with carbon dioxide from the tissues back to the lungs.) Unfortunately, hydrogen cyanide sensors are too expensive and are very difficult to replicate. Therefore as a placeholder, we created a carbon monoxide sensor.
Iteration 3: Regulating breathing to decrease heart rate and form a healthy breathing pattern. Firemen aren't aware of their breathing and pulse when it is sky rocketing. Therefore they breathe in the toxic gas at faster rate and can prevent a heart attack. captain said "watch your air" and this way the firemen would have more time to save their oxygen and avoid having a heart attack. It is important to be aware of their breathing and pulse before it reaches dangerous levels.
Biometric-Respiratory Sensor: Originally, we started experimenting with the commercial pulse sensor to get a feel for how it worked. Unfortunately, it mystified even a literal rocket scientist from MIT, so we attempted constructing a pulse sensor from scratch using a photoresistor and a red LED. Ultimately this was also a failure. We attempted to incorporate the “stethoscope” design, which works by pressing against the firefighter's neck and reading their pulse rate. The 3D printed piece and membrane coating direct sound into the mic and block out some external noise. It can sense audio signals when the heart beats, and it uses filtering algorithms to ignore speech, breathing and other interference. With this, we finally tried to meld the respiratory and pulse sensors, at which point we realized the pulse sensor was both superfluous and ineffective. This sensor is meant to measure firefighters’ respiratory rate in order to give them information on their well-being.
Biometric-Carbon Monoxide Sensor: The carbon monoxide sensor and buzzer overall went as planned. To program both the sensor and buzzer was a simple code. The carbon monoxide code programmed the sensor to read the carbon monoxide in the air and give an output reading. Depending on the number read, the buzzer would go off until the carbon sensor reads a safer level of carbon monoxide. The higher amount of carbon monoxide in their air, the higher frequency the buzzer would give off. This sensor is meant to warn firefighters when there is a dangerous amount of carbon monoxide in the air and it is time to move locations.