m-PTAS module. (A) m-PTAS sensor. (B) A user places a blood-loaded capillary tube into a slot in the m-PTAS module. Shown in inset is the magnified view of the capillary tube positioned inside the device. (C,D) The device lid is closed, and a dedicated smartphone application (“meaHb”) computes and displays [Hb] on a smartphone.