Conditions such as chronic pain, cancer and diabetes, require medications that cannot be taken orally, but must be dosed intermittently, on an as-needed basis, over a long period of time. Researchers led by Daniel Kohane, from Children's Hospital Boston (Massachusetts, USA) have devised an innovative drug delivery technique to turn dosing on and off, deliver consistent doses and adjust doses according to the patient's need. The researchers created a small implantable device, less than ½-inch in diameter, that encapsulates the drug in a specially engineered membrane, embedded with nanoparticles (approximately 1/100,000 the width of a human hair) composed of magnetite, a mineral with natural magnetic properties. When a magnetic field is switched on outside the body, near the device, the nanoparticles heat up, causing the gels in the membrane to warm and temporarily collapse. This opens up pores that allow the drug to pass through and into the body. When the magnetic force is turned off, the membranes cool and the gels re-expand, closing the pores back up and halting drug delivery. No implanted electronics are required.