The invention is an implantable electrical stimulation lead for chronic or long term use that has an improved electrical connection between the electrode and conductor. The method includes fabricating a photovoltaic module including a semiconductor assembly. In alternate embodiments of the present invention, the internal volume of the package comprises a bulk material, a bulk fiber material, fibers or fibrous materials. Removable liners may be temporarily secured to the partitions in a manner that does not comprise the integrity of the liners. Positions of the light emitter, the touch sensor and the light receiver in the apparatus are fixed with respect to each other Thus, stable and accurate measurement of transmittance can be obtained.