Low cost MFC control unit using microcontoller

Resumo

In this paper we present a compact and low cost solution to set up and to monitor an electronic Mass Flow Controller (MFC) using an Arduino microcontroller. Usually, MFCs can find a great demand at materials science laboratories, mainly in techniques which requires  a precise gas flow control, such as synthesis of thin films by Chemical Vapor Deposition (CVD). The control unit produced is presented in details by using schematic diagrams of the circuit and a detailed configuration for connect the controller to the MFC are presented. The control unit is also capable to work with two Mass Flow Controllers (MFCs) simultaneously at manual and remote (via computer software) regime. The source code is quite simple and allows the user easily modify parameters as type of gas and flux capacity of the controllers. Although the low resolution of ADC (Analog-to-Digital Converter) (10 bits) and DAC (Digital-to-Analog Converter) (using PWM - “Pulse Width Modulation”, 8 bits), the flux can be adjusted in steps of 0.4 % and 1.5 % of the total flux, respectively, which is very satisfactory for practical purposes. Finally, the operation tests were taken by using Argon (Ar) gas, and great accordance between the set point flow and the MFC measured flow was found.