A mass flow meter device utilizing a housing having a wall portion forming a chamber with an entrance and exit for passing fluid through the same. The system comprises multiple moving conveyors, including a first conveyor which transports product from an upstream location to the inner path of an accumulator conveyor. Through the bus bar, the membrane switch circuit module is connected with the main circuit board. A radioactive source is disposed in the sensing section of the housing. Diagnostic methods for detecting mutations in the coding sequence and alterations in the concentration of the polypeptides in a sample derived from a host are also disclosed. A locally-available power supply can then serve to provide power to that USB device notwithstanding the latter’s role as the host.