When nanotechnology was making its debut in the United States, few thought that the initiative would trigger innovations in Europe. Yet within a short time, European, Japanese and Indian scientists took up research relating to nano science and technology. One of the countries that have made good progress in this field is Germany. Its University of Stuttgart has developed a nano camera, slightly bigger than a grain of salt. It can be deployed for health imaging and secret surveillance.

   The dimensions of the nano camera are mind-boggling. Its three lens system—100 microns or 0.1 millimetre thick - can be inserted at the end of an optical fibre, which is just two hairs wide. The three- layered lens was built in a few hours by using 3D printing. It is also known as additive manufacture, as layers of different materials are deposited to make three-dimensional objects. Threedimensional printing is ideal for making ultra-small lenses. It is too....