and other response can be formed directly in the silicon substrate which contains the microchannel the sensor is disposed in close proximity to the chemical distribution nozzle facilitating neural and other studies microvalve arrangements can be formed with the microchannel controlled by the on chip circuitry application_number US 48906995 A description the realization of a buried flow channel in silicon in accordance with the present invention depends upon the anisotropy of the silicon etch rate in edp for example the 100 plane has an etch rate that is about 50 times faster than that of the 111 plane another consideration that is important in the practice of the present invention is that highly boron doped single crystal silicon with a doping concentration higher than 7 u00d7 10 19 cm 3 is not significantly attached in edp thus if highly boron doped silicon is used as an etch mask and an opening perpendicular to the lt 100 gt direction is cut through this layer to expose the 100 plane a subsequent wet etch in edp will undercut the mask to form a continuous flow channel fig1 is a top plan schematic representation of a silicon wafer 10 having a plurality of.