MIT has developed a jet-injection system that is superior to the devices in use for the past fifty years; the new device can deliver varying amounts of medicine to different depths inside the body.
(Lorentz-Force actuated jet-injection hypospray)
Now the MIT team, led by Ian Hunter, the George N. Hatsopoulos Professor of Mechanical Engineering, has engineered a jet-injection system that delivers a range of doses to variable depths in a highly controlled manner. The design is built around a mechanism called a Lorentz-force actuator — a small, powerful magnet surrounded by a coil of wire that’s attached to a piston inside a drug ampoule. When current is applied, it interacts with the magnetic field to produce a force that pushes the piston forward, ejecting the drug at very high pressure and velocity (almost the speed of sound in air) out through the ampoule’s nozzle — an opening as wide as a mosquito’s proboscis.
The speed of the coil and the velocity imparted to the drug can be controlled by the amount of current applied; the MIT team generated pressure profiles that modulate the current. The resulting waveforms generally consist of two distinct phases: an initial high-pressure phase in which the device ejects drug at a high-enough velocity to “breach” the skin and reach the desired depth, then a lower-pressure phase where drug is delivered in a slower stream that can easily be absorbed by the surrounding tissue.
SF fans are thinking about the hypospray, the universal injection tool in the Star Trek universe.
(Dr. McCoy with the original hypospray)
The idea of a hypospray was still pretty new for sci-fi fans in the 1960's. The jet injector gun, upon which the hypospray is based, was patented in 1960; it was used to beat smallpox. A jet injector gun uses a high-pressure, needle-narrow jet of the injection liquid. It is powered by a gas cylinder or cartridge. Workmen have been accidentally jet-injecting themselves since the 19th century (with grease).
In most of my memories of the original Star Trek series, most of the time, when Dr. McCoy used the device, he made some sort of adjustments to it. Probably making sure the right medicine was delivered to the right depth...