The effectiveness of smart pills, biosensors and drug-delivery systems depends on the surrounding tissue inside the body. To overcome this, researchers from Cal Tech have created a mini wireless chip that can vary its output frequency in relation to a local magnetic field, enabling a precise location to be determined. In addition to one day measuring factors such as pH, blood sugar, and temperature inside the body, developments like this should enable massive improvements in our ability to diagnose and treat disease as well as possibilities for life extension. http://www.kurzweilai.net/miniature-mri-simulator-chip-could-help-diagnose-and-treat-diseases-in-the-body-at-sub-millimeter-precision?