A medical microelectrode comprises portions capable of movement relative toeach other when implanted or inserted into soft tissue, so as to increase or decreasetheir distance along the electrode. The electrode is at least partially embeddedin a substantially rigid matrix that is soluble or biodegradable in a body fluid.Also disclosed are uses of the microelectrode； microelectrode bundles and arraysof microelectrode bundles and their uses； methods of inserting or implantingmicroelectrodes； microelectrode bundles and arrays of microelectrode bundlesin soft tissue.
