Digestible microchips embedded in drugs may soon tell doctors whether a patient is taking their medications as prescribed. These sensors are the first ingestible devices approved by the US Food and Drug Administration (FDA). To some, they signify the beginning of an era in digital medicine. The sandparticle sized sensor consists of a minute silicon chip containing trace amounts of magnesium and copper. When swallowed, it generates a slight voltage in response to digestive juices, which conveys a signal to the surface of a person’s skin where a patch then relays the information to a mobile phone belonging to a health care provider. Currently, the FDA and the analogous regulatory agency in Europe have only approved the device based on studies showing its safety and efficacy when implanted in placebo pills. But scientists hope to have the device approved within other drugs in the near future. Medicines that must be taken for years, such as those for drug-resistant diabetes, and for the elderly with chronic diseases, are top candidates. Proponents of digital medical devices predict they will provide alternatives to blood tests, MRIs and CAT scans. Other gadgets in the pipeline include implantable devices that wirelessly inject drug at pre-specified times and sensors that deliver a person’s electrocardiogram to their smartphone.