Component microfluidic devices which are integrated with polydimethylsiloxane microfluidic chips, include designs for an electrical and optical pressure gauge, valve, electrostatic and magnetic pumps, alternating or mixing pumps, a solenoid, a magnetometer, a magnetically actuated reversible filter and valve, and a hydrolysis valve. The stiffening member is mountable atop the central portion of the probe card. An artery, such as the brachial artery is measured for diameter before and after several minutes of either vasoconstriction or vasorelaxation. The multiplexer and the first delay element form a first delay loop. The invention uses novel and powerful, very small neodymium magnets to cover the entire surface of the roller.