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. Author manuscript; available in PMC: 2018 Jul 10.
Published in final edited form as: Sci Transl Med. 2018 Mar 7;10(431):eaap8674. doi: 10.1126/scitranslmed.aap8674

Fig. 5. Smartphone-based device hardware.

Fig. 5.

Schematic diagram of the PPG and force sensor unit and photograph of this unit, data acquisition and transmission circuitry, and power supply housed within the 3D-printed case affixed to the back of the phone. IR, infrared; LED, light-emitting diode; PD, photodetector; ADC, analog-to-digital converter; BLE, Bluetooth low energy.