US scientists have announced they have developed the world's smallest pacemaker, smaller than a grain of rice, that can be injected into the body.

The newly developed wireless pacemaker, which is only 1 millimeter thick and 3.5 millimeters long, is small enough to fit in the tip of a syringe. The device is paired with a soft patch that is attached to the patient's chest. When the patch detects irregular heartbeats, it sends light signals to tell the pacemaker which rhythm to stimulate. Scientists have described the wireless pacemaker, which is planned to be tested on humans in the future, as a 'breakthrough invention'. The author of the study, Prof. John Rogers from Northwestern University in the US, stated that the pacemaker could begin to be tested on humans in 2 to 3 years. It has been stated that this innovative device may also inspire developments in other areas in the world of medicine.