In some examples, a medical device system a thin film including at least one electrically conductive track extending between at least one electrode and at least one electrical contact, a first and second polymer layer; wherein, at a portion of the thin film between the at least one electrode and the at least one electrical contact, the first polymer layer and second polymer layer surround the at least one electrically conductive track; and at least one discrete ceramic member located between the first and second polymer layers at a portion of the thin film between the at least one electrode and the at least one electrical contact, wherein the at least one discrete ceramic member does not surround the at least one conductive track, and wherein the at least one discrete ceramic member is configured to increase adhesion between the first polymer layer and second polymer layer.