A pressure sensor is provided, wherein a ballast resistive layer is integrated in the pressure sensor so that the resistive output curve for the pressure sensor has saturation characteristics. In one embodiment, the antenna unit includes at least one remote antenna circuit having one or more ports to receive a control signal and a transmit signal transmitted from the WAP located in a multi-tone transmitter-receiver. An effective diameter of the first access port is larger than an effective diameter of the second access port when the effective diameters of the first and second access ports are defined as a diameter of a cylinder that is insertable into the first and second access ports. Each branch is connected back to the begin option node through a next option node. This provides high-quality blood flow images with shorter scan time, without injecting a contrast medium. Methods and apparatuses for cryoprecipilation and chromatography are also disclosed.