An instrument with a first conduit for emitting a first fluid from a first opening of the first conduit in an axial direction into a reacceleration zone and with a second conduit for channeling of a second fluid in the reacceleration zone in the axial direction is provided such that active ingredient components, e.g. cells, of the second fluid are reaccelerated in the axial direction as a result of a flow in the reacceleration zone by means of the first fluid that enters the reacceleration zone. A coaxial configuration of the first and the second conduit is preferred, because in doing so, around the first opening a shell jet of the second fluid can be created that flows downstream in the axial direction around a central working jet. In addition, a head for an inventive instrument and an application system with an inventive instrument is provided.

Core annular flow is used to enable the subcutaneous delivery of a viscous fluid such as a protein therapeutic formulation. The high-viscosity fluid is surrounded by a low-viscosity fluid, and the low-viscosity fluid lubricates the passage of the high-viscosity fluid. This allows the use of protein formulations that have a higher concentration and a higher viscosity at comparatively reduced injection forces and reduced injection times. Several different embodiments of injection devices that provide core annular flow are described herein.

Core annular flow is used to enable the subcutaneous delivery of a viscous fluid such as a protein therapeutic formulation. The high-viscosity fluid is surrounded by a low-viscosity fluid, and the low-viscosity fluid lubricates the passage of the high-viscosity fluid. This allows the use of protein formulations that have a higher concentration and a higher viscosity at comparatively reduced injection forces and reduced injection times. Several different embodiments of injection devices that provide core annular flow are described herein.