The association of microneedles with electric pulses causing electroporation could result in an efficient and less painful delivery of drugs and DNA into the skin. Hollow conductive microneedles were used for (1) needle-free intradermal injection and (2) electric pulse application in order to achieve electric field in the superficial layers of the skin sufficient for electroporation. Microneedle array was used in combination with a vibratory inserter to disrupt the stratum corneum, thus piercing the skin. Effective injection of proteins into the skin was achieved, resulting in an immune response directed to the model antigen ovalbumin. However, when used both as microneedles to inject and as electrodes to apply the electric pulses, the setup showed several limitations for DNA electrotransfer. This could be due to the distribution of the electric field in the skin as shown by numerical calculations and/or the low dose of DNA injected. Further investigation of these parameters is needed in order to optimize minimally invasive DNA electrotransfer in the skin.

International audienceMicromachined needles provide a promising technology for painless delivery of molecules or foreign substance into a living cell. Over the recent years, a variety of different microneedle shapes and materials have been studied and have shown their facility to disrupt stratum corneum layer to increase the skin permeability. In this paper, we described an alternative process to fabricate high and beveled hollow out-of-plane microneedles. Silicon microneedles dimensions are 40–60 lm in inner diameter, 150–200 lm in outer diameter and over 700 lm in height. Tip angles reached are from 30 to 45

We report a microfluidic device able to control the ejection of fluid through a matrix of out-of-plane microneedles. The device comprises a matrix of open dispensing units connected to needles and filled by a common filling system. A deformable membrane (e.g. in PDMS) is brought into contact with the dispensing units. A pressure exerted on the deformable membrane will close (and thus individualize) each dispensing unit and provoke the ejection of the dispensing unit content through the outlets. A sufficient pressure over the deformable membrane will ensure that all dispensing units will deliver a fixed volume (their content) irrespective of the hydrodynamic pressure outside the dispensing unit outlet. The size of the ensemble matrix of dispensing units, the number of liquid reservoirs, as well as the material can vary depending on the considered application of the device or on the conditions of use. In the present paper, the liquid reservoirs are gemetricaly identical. The geometrical parameters of the device are optimized to avoid as much dead volume as possible, as it was though to handle plasmid DNA solutions which are very expensive. The conception, the fabrication and the experimental results are described in the paper. Our prototype is conceived to inject in a uniform way 10 µl of drug through 100 microneedles distributed over one square centimetre.