Jet injectors use a high-speed fluid jet to pierce the skin and have been widely used to deliver drugs to different skin layers. This technique has also been used recently to release blood from capillaries, with the aim to replace lancet pricks for applications such as glucose monitoring. This work investigates the tissue disruption caused by jet injection, and by lancet pricks, using histology. We investigate the geometry of the wound, and the disruption to the vascular endothelium, induced by jet injection through a lancet-inspired slot nozzle, jet injection with a standard circular nozzle, and a conventional lancet prick. The slot-shaped jet was designed to mimic the slit-shaped wound caused by the lancet prick and anticipated to release blood in a manner like a lancet prick.
Intradermal injection into porcine skin via the slot-shaped nozzle resulted in half the penetration depth and one-fifth the wound volume of the jet injection with the circular nozzle. Nevertheless, the slot-shaped jet disrupted more vascular endothelium in the tissue and can be expected to release more blood than the circular jet. The wound volume did not directly correlate with the volume of vascular endothelium being disrupted. The findings demonstrate that jet injection can be used to disrupt small blood vessels in the skin and has the potential to release capillary blood and provide sufficient blood for glucose measurement. This work opens the door for controllable jet injectors to be used to release and collect capillary blood samples in diabetes management. To the best of the authors’ knowledge, this is the first report of the potential disruption of capillaries from jet injection into porcine skin.