Development of individually-addressable parylene microtube arrays

This paper reports a novel technology of microfabricating out-of-plane parylene microtube arrays with integrated in-plane microchannels. The integrated microchannels enable the individual addressing of the microtubes. These devices permit the delivery of chemicals with controlled temporal and spatial patterns and facilitate the study of neurotransmitter-based retinal prosthesis. To fabricate these devices, through-silicon vias and horizontal trenches are first created by deep reactive-ion etching and isotropic XeF₂ etching. Then, the parylene microtubes and microchannels are simultaneously formed by depositing parylene inside the vias and trenches conformally. Two types of devices have been fabricated and characterized. One type of device is rigid with microtube arrays and microchannels fabricated on the same chip. The other type is flexible, integrated with flexible parylene cables, which can be used for in vivo animal study of retinal prosthesis.