A jet injector is a type of medical injecting syringe that uses a high-pressure narrow jet of the injection liquid instead of a hypodermic needle to penetrate the epidermis, the purpose being to reduce the pain associated with needle injection. It is powered by compressed air or gas, either by a pressure hose from a large cylinder, or from a built-in gas cartridge or small cylinder. Some are multi-shot, and some are one-shot. They are made in various shapes, as the links to images below show.

They are used by diabetics to inject insulin as an alternative to needle syringes, though they are still not very common.

In the Star Trek franchise, and sometimes in other fictional scenarios and occasionally in the real world, it is called a hypospray.

Types of jet injector

Jet Injectors
A Med-E-Jet vaccination gun from 1980

The Jet Injector Gun and the Ped-O-Jet are air-powered medical injector devices designed to administer vaccinations in an extremely efficient manner. Invented by Aaron Ismach, these medical devices were bought in mass quantities by the US Government and provided to governments around the world to eradicate smallpox and other diseases. Servicemen in the Armed Forces were routinely injected with these medical devices to immunize them, and civilian usage included vaccinations during flu epidemics and the like. The Jet Injector is powered by electricity, while the Ped-O-Jet version is powered by a foot pump and does not require electricity to administer the vaccines. These devices have various specialized nozzles for different medication densities and also permitted the efficient inoculation of animal populations as well.

The Biojector 2000 is a make of gas-cartridge-powered jet injector. It is claimed that it can deliver intramuscular injections and subcutaneous injections up to 1 milliliter. The part which touches the patient’s skin is single-use and can be replaced easily. It can be powered from a big compressed gas cylinder instead of gas cartridges. It is made by Bioject.

In October 2006 it was in clinical trials for patients using Fuzeon as part of their HAART treatment for HIV. For clinical trial and related information see http://www.hivdent.org/drugs1/drugBIFI0306.htm