A medical microelectrode comprises portions capable of movement relative toeach other when implanted or inserted into soft tissue, so as to increase ordecrease their dis-tancealong the electrode. The electrode is at least partially embedded in asubstantially rigidmatrix that is soluble or biodegradable in a body fluid. Also disclosed areuses of the microelec-trode；microelectrode bundles and arrays of microelectrode bundles and their uses；methods ofinserting or implanting microelectrodes； microelectrode bundles and arrays ofmicroelectrodebundles in soft tissue.
