The city's mosquitoes are in for a big and deadly surprise - a trap that smells like a human and gives off body heat. By replicating human breath, body heat and scent, the mobile mosquito trap is aimed at outwitting the troublesome insects, which carry, among other diseases, dengue fever. The trap is one of the products on display at the Innovation Expo 05 at the Convention and Exhibition Centre. Everything from mobile oxygen generators to sophisticated calibrators are being shown at the four-day event. The mobile mosquito trap, developed by local firm Waste and Environmental Technologies, is designed to be placed in parks. Its appearance is timely, given the government's concern about dengue fever, and the Leisure and Culture Services Department has already bought 120 this year. Not all exhibitors are targeting the local market. Many clearly have the mainland in mind. Celki Medical Company has developed a mobile oxygen generator it aims to sell to small hospitals on the mainland. Company president Raymond Choi said transportation of large oxygen containers on the mainland was often difficult because of long distances and poor roads. 'It would be much better if they had machines that could generate oxygen, especially hospitals in rural areas,' he said. But not everything is being displayed with commercial gain in mind. An example is a sophisticated calibrator that measures the accuracy of other measuring equipment. Electrical and mechanical engineer Francis Wong Seung-yin, of the government's Innovation and Technology Commission, said the laser calibrator invented by the commission was accurate to 0.0001 of a millimetre. This compared with conventional measuring equipment in secondary schools and universities that had an accuracy of 0.001 of a millimetre. Mr Wong said the commission had recently placed a special cover on the calibrator, which reduced fluctuations in readings. The expo ends on Sunday and admission is free.