A method of biodissolving in an aqueous medium at least a part of a device, the part of the device being made of N-acetylchitosan with a degree of acetylation of more than 3% and less than 25%. In the method, the biodissolution of the part of the device is controlled by adjusting the pH of the aqueous medium in contact with the N-acetylchitosan part of the device to a value of equal or less than 6.0.