Method and device for detecting heavy metal ion in water

The invention discloses a method and a device for detecting heavy metal ion in water. The method comprises (1) providing detecting material including hydrophilic layer at least partially covered by hydrophobic layer, wherein the hydrophobic layer is selected from long-chain compound such as long-chain thiol, long-chain fatty acid and combination thereof, the region covered by the hydrophobic layer is taken as detection region, and initial contact angle between the detection region surface and water is not less than about 120 degrees; (2) contacting the detection region with to-be-detected aqueous solution; (3) judging whether hydrophobic-hydrophilic change occurs at detection region surface after contact; and (4) accordingly determining whether heavy metal ion exists in the to-be-detected aqueous solution.