An unstable radioactive element discovered by scientists only a few years ago, Quadruinium was initially a substance with very few plausible applications. With technology of the 28th Century having long since moved onto fusion power, Quadruinium's viability as a power source was superfluous at best.
It wasn't until the research and development teams at Tangent Technologies were able to acquire samples of Quadruinium that they managed to unlock its potential. While testing its viability as the next step up from conventional nuclear weaponry by observing its interaction with human tissue, they noticed a startling and unexpected side-effect when it came into contact with blood.
When mixed with haemoglobin, the Quadruinium underwent a chemoluminescent (light-emitting) reaction and created the compound Tyraxium. Tyraxium, the scientists found, had powerful refractive properties; sufficient to render their test samples almost invisible. With a potential breakthrough on their hands, the scientists petitioned for live human testing of the element. Sure enough, after considerable trial and error, they were able to find a dosage sufficient to exhibit the same reaction in the larger-scale arena of the human body.
Following this breakthrough, the first wrist-mounded Quadruinium injectors were quickly rolled out to the specialist market. With these injectors, users finally had their own real-life version of personal stealth technology. However, due to the halflife of Tyraxium when in the human body, each dose lasts - at the most - around ninety seconds before it breaks down. Although it is possible to overdose on the chemical, its incredibly short lifespan once introduced to the bloodstream makes it very difficult to do so, allowing it to be sold over the counter in places such as HEW without issue.