An affordable and effective device for detecting skin cancer has picked up an award of £30,000 ($40,000) from Britain's best-known inventor. This year's James Dyson prize for engineering was given to a group of four Canadian graduates, for their sKan system. The gadget picks up on subtle changes in the skin's ability to retain heat, which can indicate the presences of cancerous tissue. The device costs £760 ($1,000), compared with the £20,000 ($26,000) for high-resolution thermal imaging cameras. An affordable and effective device for detecting skin cancer has picked up an award of £30,000 ($40,000) from Britain's best-known inventor.