The untold invention story of smoke detectors
Not all inventions, scientific or otherwise, happen as per plan. Some are momentous or even accidental. For instance, bacteriologist Alexander Fleming was not even thinking of antibiotics but he ended up inventing penicillin. Similarly, Swiss engineer George de Mestral was having a regular day, being back from his walk with his pet dog and he realised how a particular plant had the most amazing hooking ability as it was attached to both his clothes and the dog’s furs. Thus, Velcro was born.
Today, we are going to tell you about another such accidental invention – it’s that of smoke detectors.
The pre-smoke detector era
For ages, humans have struggled to put out fires because they hardly knew it was coming or realised when it was too late. With that in mind, American physicist and mathematician Francis Robbins Upton, who was an associate of Thomas Edison invented an electric fire alarm and patented it in 1890. But there was a slight disadvantage to this device. It could only work when there was already a full-fledged fire around and that too if the device was nearby. Following his footsteps in 1902, an English born innovator named George Andrew Darby made a similar device called European electrical heat detector. As the name suggests, it was supposed to detect heat. But unfortunately, his invention wasn’t a success.
Looking for a poison gas detector
Fast forward to the 1930s now, when Swiss physicist Walter Jaeger was working with poisonous gases such as carbon monoxide and wished to invent a sensor for such toxic gases. But his trigger was far more serious. Back in his hometown Wengen, in a small-scale private laboratory, a gas tragedy claimed lives of one of his closest childhood friends. This made Jaeger determined to find a solution that would permanently evade such accidents.
Anyhow, he did make a prototype and expected that gas would enter its sensor, bind the ionised air molecules and in turn alter the electric current in the circuit, making a noise. Unfortunately, Jaeger’s invention failed to do so, as only a small concentration of gas could enter the device and hardly affected the sensor’s conductivity. At this moment, Jaeger was justifiably frustrated and lit himself a cigarette. He wanted to rethink his idea and rework on the prototype. This is when, something unexpected and wonderful happened.
The smoke of the cigarette entered the sensor and was able to shift the electric current, something he was meaning to do with poison gas, but failed. Not only that, it lit the device and even made the desired sound. It was as if the instrument was warning that some kind of a smoke was around and it was better to run! Thus, the first smoke detector was born!
Smoke detectors kick off
While Jaeger did make a stunning invention, he didn’t really know what to do. In fact, many say, he wanted no credit for it, but was only interested in its positive social impact. Thus, when in 1939, another Swiss physicist Ernst Meili decided to improve on Jaeger’s idea, he was more than welcoming. What Meili did was make the device commercially viable by simply devising a larger ionisation chamber device capable enough to detect combustible gases in mines. He also added a cold cathode tube that would amplify the small signal and make it strong enough to activate a light and sound alarm. Even though Meili’s model was kind of perfect, he needed to convince a lot of stakeholders and it was more than a decade later in 1951 that the first ionisation smoke detectors started selling in the USA. However, they were meant for industrial purposes only. It was later in 1955 that smoke detectors for homes were developed, followed by single-station smoke detector in 1970. Today however, we use 10-year-lithium-battery-powered smoke alarms and almost 20 million units are sold worldwide annually.