A catheter, comprising: an elongate shaft (107; 134; 154; 389; 495; 702; 780) comprising a proximal end and a distal end, wherein the elongate shaft defines a shaft longitudinal axis; a flexible tip portion (110; 122; 156; 202; 228; 248; 282; 322; 362; 491) comprising a plurality of microelectrodes (102; 124); a connective stem (326; 366; 458) having a longitudinal axis and comprising a first connective stem member (332; 380; 464; 640) and a second connective stem member 334; 378; 466; 610) that are configured to be assembled together with a proximal end portion of the flexible tip portion disposed therebetween, wherein the connective stem defines a first sensor groove in the first connective stem member and a second sensor groove in the second connective stem member in an exterior surface of the connective stem; a coupler (324; 364; 462; 560; 720; 760; 802) configured for coupling with the connective stem after insertion of the connective stem into the distal end of the elongate shaft; a first five degree of freedom magnetic position sensor (328-1; 382-1; 499-1; 714-1; 801-1) disposed in the first sensor groove, elongated along a first sensor longitudinal axis, and including a first coil wound about the first sensor longitudinal axis; and a second five degree of freedom magnetic position sensor (328-2; 382-2; 499-2; 714-2) disposed in the second sensor groove, elongated along a second sensor longitudinal axis that is oriented at an angle relative to the first sensor longitudinal axis, and including a second coil wound about the second sensor longitudinal axis, wherein the connective stem (326; 366; 458) includes a six degree of freedom sensor assembly including the first and second five degree of freedom magnetic position sensors. an elongate shaft (107; 134; 154; 389; 495; 702; 780) comprising a proximal end and a distal end, wherein the elongate shaft defines a shaft longitudinal axis; a flexible tip portion (110; 122; 156; 202; 228; 248; 282; 322; 362; 491) comprising a plurality of microelectrodes (102; 124); a connective stem (326; 366; 458) having a longitudinal axis and comprising a first connective stem member (332; 380; 464; 640) and a second connective stem member 334; 378; 466; 610) that are configured to be assembled together with a proximal end portion of the flexible tip portion disposed therebetween, wherein the connective stem defines a first sensor groove in the first connective stem member and a second sensor groove in the second connective stem member in an exterior surface of the connective stem; a coupler (324; 364; 462; 560; 720; 760; 802) configured for coupling with the connective stem after insertion of the connective stem into the distal end of the elongate shaft; a first five degree of freedom magnetic position sensor (328-1; 382-1; 499-1; 714-1; 801-1) disposed in the first sensor groove, elongated along a first sensor longitudinal axis, and including a first coil wound about the first sensor longitudinal axis; and a second five degree of freedom magnetic position sensor (328-2; 382-2; 499-2; 714-2) disposed in the second sensor groove, elongated along a second sensor longitudinal axis that is oriented at an angle relative to the first sensor longitudinal axis, and including a second coil wound about the second sensor longitudinal axis, wherein the connective stem (326; 366; 458) includes a six degree of freedom sensor assembly including the first and second five degree of freedom magnetic position sensors.