A needle-free technique for interstitial fluid sample acquisition using a lorentz-force actuated jet injector.

We present a novel method of quickly acquiring dermal interstitial fluid (ISF) samples using a Lorentz-force actuated needle-free jet injector. The feasibility of the method is first demonstrated on post-mortem porcine tissue. The jet injector is used to first inject a small volume of physiological saline to breach the skin, and the back-drivability of the actuator is utilized to create negative pressure in the ampoule and collect ISF. The effect of the injection and extraction parameters on sample dilution and extracted volumes is investigated. A simple finite element model is developed to demonstrate why this acquisition method results in faster extractions than conventional sampling methods. Using this method, we are able to collect a sample that contains up to 3.5% ISF in 3.1s from post-mortem skin. The trends revealed from experimentation on post-mortem skin are then used to identify the parameters for a live animal study. The feasibility of the acquisition process is successfully demonstrated using live rats; the process is revealed to extract samples that have been diluted by a factor of 111-125.