Angel (by Seraphim Sense Ltd) is a wristband sensor that delivers heart rate, blood oxygen, temperature, and activity information. Angel is completely open to enable app makers to participate in digital health without the need to design custom hardware. The Angel Sensor app provides basic access to the wristband, allowing users to browse the metrics history and extract and display real-time metrics from Angel. It can be used to configure Angel, set alarm clocks, update firmware, etc. The Angel Sensor app is part of Seraphim'sopen-source SDK.