No abstract

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.