A smart interface for reliable intradermal injection and infusion of high and low viscosity solutions

We present a smart intradermal interface suitable for skin-attached drug delivery devices. Our solution enables injections or infusions that are less invasive compared to subcutaneous injections and are leakage-free at the location of penetration.

The intradermal interface is based on a 31-gauge cannula embedded in a slider, movable relative to a carrier plate that can easily be fixed onto the skin. By simply pushing the slider, the cannula is inserted into the dermis.

We performed injections and infusions with stained water and polyethylene glycol (PEG) solution in ex vivo pig skin. The sizes of coloured spots in the skin range from 3.5 mm(2) to 15.4 mm(2) for stained water depending on the infused volume. Infusing stained PEG solution resulted in stained tissue areas about one order of magnitude larger. One of three investigated leakage modes is unacceptable but can be reliably avoided by proper site selection. At low flow rates and at the beginning of an infusion an initial back pressure overshoot was identified. This effect was identified as the limiting parameter for the design of small programmable or intelligent devices based on micro actuators.

With the proposed easy-to-use interface, intradermal injections and infusions can be performed reliably. Therefore, it is supposed to be an ideal and clinically relevant solution for self-administration of parenteral drugs in home care applications.