Out-of-Plane Microtube Arrays for Biomedical Sensors Using Vapor-Liquid-Solid Growth Method

This paper reports on a novel technique for realizing submicron and micron diameter SiO₂ tubes on a Si substrate for biomedical applications such as, for example, patch clamps. The tube arrays have been successfully fabricated on Si substrates using a selective vapor-liquid-solid (VLS) growth method combined with MEMS techniques. The size of the tubes is typically between 0.2 mum and 2 mum in diameter and from 8 mum to 40 mum in length. The dimensions are controlled by the diameter of a Au pattern and the VLS growth time. The tubes were coated with parylene, a biocompatible material, which makes them stronger. The diameter is such that the array can be used in biomedical applications where insertion of the tubes into tissue is minimally invasive. Water flow experiments through the tubes were carried out successfully without the tubes breaking.