A pressure sensor configured for biological pressure measurement at a distal end portion of an elongated member comprises a dissolvable hydrophilic material coated on a surface of the pressure sensor. A guide wire for biological pressure measurement may include a tube extending along a longitudinal axis of the guide wire; and a pressure sensor for biological pressure measurement, at least a portion of the pressure sensor being mounted within the tube. The pressure sensor comprises a pressure sensor membrane facing a top side of the tube. A circumferential wall of the tube includes at least six openings: a first distal opening, a second distal opening located on a right side of the tube, a third distal opening located on a left side of the tube, a first proximal opening, a second proximal opening located on a right side of the tube, and a third proximal opening located on a left side of the tube. The first distal opening is larger than the second and third distal openings, and the first proximal opening is larger than the second and third proximal openings.