Abstract: A rim for protecting a handheld computing device, such as a smartphone, has left, right, top, and bottom edges sized to engage the corresponding edges of the handheld device. An electronic processor is disposed within at least one of the rim edges, and is able to communicatively connect to the handheld computing device when the handheld computing device is engaged by the rim. The rim resiliently stretches over the handheld device to engage the device, the resilient material further operative to protect the device from damage due to dropping. Sensors are communicatively coupled to the electronic processor, the sensors operable to detect a health parameter of the body of the user when the user grasps the rim engaged with the handheld computing device, and uses the handheld computing device in a normal manner. Electronic backplates having differing features can be attached to the rim and communicate with the rim.