High-Accuracy Microflow Controllers Using Fluidic Digital-to-Analog Converters

Abstract

This paper presents 4-digit digital microflow controllers where fluidic digital-to-analog converters (DACs) achieve an improved linearity with finer flow-rate levels for a given number of digital valves. The fluidic DAC, composed of microchannels with binary-weighted flow resistors, controls flow-rate levels not based on the magnitude of flow resistances, but based on the ratio of the flow resistance. We deign the flow resistance of microchannel using a serial or a parallel connection of an identical fluidic resistor, thus making the controllable flow-rates insensitive to the micromachining errors. Prototype S and P with serial and parallel connections of a unit fluidic resistor and prototype V with the fluidic resistors having different channel width are fabricated using micromachining. At a constant pressure of 2kPa, prototypes S, P and V show the maximum error of 7.5%, 6.2% and 22.5% in the flow-rate range of 0.09μ1/s to 3.33μ1/s, resulting in the differential nonlinearity of 0.28, 0.27 and 0.94, respectively. The prototypes S and P show 70.2% and 71.2% less sensitive to micromachining errors than prototype V, respectively.