#$%^&*AU2018202763A120180517.pdf#####ABSTRACT The present invention relates to a peripheral device to be placed over an image sensor and a light source of a portable computing device to assist the portable computing device in reading a reaction area on a test strip in the peripheral device, the peripheral device comprising a light guide to direct light from the light source to the test strip, and an alignment feature to aid placement of the peripheral device relative to the image sensor and the light source on the portable computing device.