An implantable stimulator, comprising: a substrate (300, 1400) comprising a first surface and a second surface, wherein a thickness of the substrate (300, 1400) is defined by the first and second surfaces; the substrate (300, 1400) comprising a first portion (2010, 2110, 2210, 2310) along which a pulse generator is located, the pulse generator comprising one or more electrical or electronic components, configured to generate at least one stimulation pulse; an electrode array (200, 400, 1220) comprising at least two electrodes located along a conformable second portion (2020, 2120, 2320) of the substrate (300, 1400); a plurality of electrical interconnections (250, 1210) electrically coupling the pulse generator to the at least two electrodes of the electrode array (200, 400, 1220), wherein the plurality of electrical interconnections (250, 1210) are positioned between the first and second surfaces of the substrate (300, 1400), the implantable stimulator (100, 101, 102, 103, 104, 105, 1110, 1111, 2101, 2201, 2301) comprising one or more electrical interfaces between the first portion (2010, 2110, 2210, 2310) and the conformable second portion (2020, 2120, 2320), the one or more electrical interfaces being between the plurality of electrical interconnections (250, 1210) and the pulse generator; wherein the implantable stimulator (100, 101, 102, 103, 104, 105, 1110, 1111, 2101, 2201, 2301) comprises at least one conductive elastomer, configured and arranged to electrically connect one or more electrical interfaces between the plurality of electrical interconnections (250, 1210) and the pulse generator; wherein the thickness of the substrate (300, 1400) along the conformable second portion (2020, 2120, 2320) is equal to or less than 0.5 millimeters; the implantable stimulator further comprising at least one encapsulation layer (1300, 1310, 1320, 2150, 2250) at least partially covering the first portion (2010, 2110, 2210, 2310) and at least partially covering the conformable second portion (2020, 2120, 2320) of the substrate (300, 1400), the at least one encapsulation layer (1300, 1310, 1320, 2150, 2250) being configured to resist separation of the conformable second portion (2020, 2120, 2320) from the first portion (2010, 2110, 2210, 2310) at the meeting of the first portion (2010, 2110, 2210, 2310) and the conformable second portion (2020, 2120, 2320); and wherein the at least one encapsulation layer (1300, 1310, 1320, 2150, 2250) is configured and arranged to provide a degree of mechanical pre-tension such that one or more conducting paths through the at least one conductive elastomer is created. the substrate (300, 1400) comprising a first portion (2010, 2110, 2210, 2310) along which a pulse generator is located, the pulse generator comprising one or more electrical or electronic components, configured to generate at least one stimulation pulse; an electrode array (200, 400, 1220) comprising at least two electrodes located along a conformable second portion (2020, 2120, 2320) of the substrate (300, 1400); a plurality of electrical interconnections (250, 1210) electrically coupling the pulse generator to the at least two electrodes of the electrode array (200, 400, 1220), wherein the plurality of electrical interconnections (250, 1210) are positioned between the first and second surfaces of the substrate (300, 1400), the implantable stimulator (100, 101, 102, 103, 104, 105, 1110, 1111, 2101, 2201, 2301) comprising one or more electrical interfaces between the first portion (2010, 2110, 2210, 2310) and the conformable second portion (2020, 2120, 2320), the one or more electrical interfaces being between the plurality of electrical interconnections (250, 1210) and the pulse generator; wherein the implantable stimulator (100, 101, 102, 103, 104, 105, 1110, 1111, 2101, 2201, 2301) comprises at least one conductive elastomer, configured and arranged to electrically connect one or more electrical interfaces between the plurality of electrical interconnections (250, 1210) and the pulse generator; wherein the thickness of the substrate (300, 1400) along the conformable second portion (2020, 2120, 2320) is equal to or less than 0.5 millimeters; the implantable stimulator further comprising at least one encapsulation layer (1300, 1310, 1320, 2150, 2250) at least partially covering the first portion (2010, 2110, 2210, 2310) and at least partially covering the conformable second portion (2020, 2120, 2320) of the substrate (300, 1400), the at least one encapsulation layer (1300, 1310, 1320, 2150, 2250) being configured to resist separation of the conformable second portion (2020, 2120, 2320) from the first portion (2010, 2110, 2210, 2310) at the meeting of the first portion (2010, 2110, 2210, 2310) and the conformable second portion (2020, 2120, 2320); and wherein the at least one encapsulation layer (1300, 1310, 1320, 2150, 2250) is configured and arranged to provide a degree of mechanical pre-tension such that one or more conducting paths through the at least one conductive elastomer is created.