A sample holder includes a substrate composed of ceramics, having a sample holding surface provided in an upper face thereof; a supporting member composed of metal, an upper face of the supporting member covering a lower face of the substrate; and a joining layer composed of indium or an indium alloy, the substrate and the supporting member being joined to each other via the joining layer. Furthermore, the invention describes a method of making an implant as per the invention. A voltage regulator is also shown for maintaining midpoint voltage during unequal loading of different actuator coils in the converter.