A flexible probe includes a probe body having a distal end and a proximal end, and comprises at least one flexible nanoelectronic thread having a distal end and a proximal end and a length therebetween, the nanoelectronic thread comprising at least one electrode positioned on a top surface of the nanoelectronic thread, and at least one nanoscale wire is partially encapsulated, having a first portion electrically connected to at least one of the electrodes and a second portion surrounded by a dielectric insulator, the probe further including at least one external trace electrically connected to the at least one nanoscale wire at the proximal end of the at least one nanoelectronic thread, the at least one external trace having a width larger than the width of the at least one nanoscale wire, and an interface connector near the proximal end of the probe body, electrically connected to the at least one electrode via the at least one nanoscale wire and the at least one external trace, wherein the at least one nanoscale wire has a width less than 250 nm, and wherein the nanoelectronic thread has a cross-sectional area that is less than 30 μm2. Methods of fabricating and implanting a flexible probe are also described.