A small device with moving parts can release drugs and be wirelessly controlled after being placed in the body.
Sau Yin Chin
Sau Yin Chin and Samuel Sia at Columbia University in New York and their colleagues used biocompatible hydrogels to build the device, which is just over 1 centimetre wide (pictured). They designed different versions, layer by layer, that contained various moving parts, such as valves, pumps and rotating gears.
One version included a Geneva drive, a mechanism found in watches, that precisely controls intermittent movement. The team loaded a Geneva-drive device with a cancer drug and placed it under the skin of tumour-bearing mice. The researchers activated the device using an external magnet every two days to locally release low doses of the drug. They found that this treatment inhibited tumour growth more than high systemic doses of the drug.