Patients could soon be swallowing microchips in their tablets. The chips would then report when treatments had been taken and what effect they had on the patient.

Other microchips could also be placed under the skin to deliver drugs ranging from pain medication to chemotherapy. These chips, in the advanced stages of trials, are designed with tiny compartments loaded with multiple drugs and covered with caps. Applying an electrical signal dissolves the caps and releases the medication.

The "smart" delivery systems are being pioneered by Robert Langer, at the Massachusetts Institute of Technology. He said several smart pills that can release drugs for days, months or years were being tested.

Separately, a Silicon Valley company called Proteus Biomedical is developing what it calls the Raisin system of microchipped pills to help to tackle the problems of patients forgetting or refusing to take medicines.

Each pill contains a microchip that can send data to a receiver in a patch or under the skin. This can then be analysed to alert carers if a pill has not been taken.

The company hopes to have the system on the market in 2011.