Apple may be diving deeper into the health-care industry.The company filed a patent application for a wearable device that can measure electrocardiographic (ECG) signals through a series of sensors, according to a filing published by the U.S. Patent and Trademark Office (USPTO) today (Aug.11). The application leaves the form of the device open ended—it could be a ring, a bracelet, a brooch, or something else—but its sole function is to monitor the heart.The company has already identified health care as an area of big potential. Last year, it released ResearchKit, an open source software framework designed to help doctors and scientists gather data from participants using iPhone apps. And wearables like the Apple Watch are natural ways to collect a variety of information. But the patent application points to something more targeted and sophisticated.