1. A portable electronic device, comprising:an upper enclosure;
a display positioned within the upper enclosure;
a lower enclosure pivotally coupled to the upper enclosure and comprising:a translucent layer defining an external surface; and
an opaque layer coupled to the translucent layer and defining an array of micro-perforations;
a keyboard positioned within the lower enclosure;
a bio-sensor positioned within the lower enclosure below the array of micro-perforations and comprising:a light source operable to transmit light through the array of micro-perforations into a body part of a user; and
a light receiver operable to receive reflected light from the body part of the user; and
a processing unit, communicably coupled to the light receiver and operable to determine a health metric based on the reflected light.