An Electronic Force Sensor for Medical Jet Injection

In medical jet injection, a narrow fluid drug stream is propelled at high velocity into skin without a needle. Previous studies have shown that the volume delivered is highly dependent on a number of factors. This paper details the development of an electronic force sensor for medical jet injection and shows that the normal contact force exerted on the tissue by the nozzle is an additional factor affecting volume delivered. Using this sensor, we measure the forces at the nozzle tip in the normal direction with a sensitivity of 18  μN, calibrated over a range from 1  N to 8 N with a mean absolute error of 8 mN, and a maximum overload of 300 N. We further measure forces at the nozzle tip in the lateral direction with a sensitivity of 8 μN, calibrated over a range from 0.1  N to 7 N, with a mean absolute error of 101 mN for lateral contact force magnitude and 1.60 deg for lateral contact force direction. Experimental validation confirms that the force sensor does not adversely affect the accuracy and precision of ejected volume from the jet injector. We use th is setup to examine the effect of normal contact force on volume delivered into postmortem porcine tissue. Experimental results demonstrate that volume delivered with normal contact force between 4 N and 8 N is significantly more accurate and precise compared to volume delivered with normal cont act force between 0 N and 3.9 N.

Source: Journal of Medical Devices, Transactions of the ASME - April 11, 2019 Category: Medical Devices Source Type: research