Out-of-plane microtube arrays for drug delivery-liquid flow properties and an application to the nerve block test

We have proposed fabricating very fine out-of-plane silicon-dioxide microtube arrays using a selective vapor-liquid-solid (VLS) growth technique and microfabrication processes. In this study, we elucidated the liquid-flow properties of microtubes with different inner diameters. Our fabricated microtubes were 0.5 mu m in wall thickness; 20 mu m in height; and either 2.5 mu m, 4.1 mu m, 4.6 mu m, or 6.4 mu m in inner diameter. We determined the relationship between the flow pressure and the liquid flow rate through the microtube. We also conducted a nerve block test, in which a microtube with 4.6 mu m inner diameter was used to administer lidocaine solution (Na channel blocker) to the rat sciatic nerve. This successful test represents the first reported use of a microtube for drug delivery to the peripheral nerve of a rat. We conclude that the proposed microtube array and its fabrication process might contribute to developing pharmacological devices.