The invention provides a method of thermally deprotecting the internucleosidic phosphorus linkage of an oligonucleotide, which method comprises heating a protected oligonucleotide in a fluid medium at a substantially neutral pH, so as to deprotect the oligonucleotide. A membrane partitions the symmetrical first and second cavities. The second layer is arranged on the outside, and visually closes off the perforation, and the outer layer comprises an air-permeable woven fabric. The plurality of first sub-electrodes are located further in the second direction than any of the plurality of second sub-electrodes. The inflatable artificial muscle is activated by inflating the bladder with a pressurizing fluid to a predetermined internal pressure.