SpiroMilli: Bringing Ad-hoc Spirometry to 5G Devices

Figure 1: (a) Exhalation on a mmWave device; (b) Phase of the reflected signal shows tiny vibrations during airflow; (c) Timesynchronized vibration signals from multiple phased-array antennas; (d) Signal processing to improve fidelity, track moving reflectors, and estimate distance-invariant vibration; (e) CNN-LSTMarchitecture tomap physical vibration to 7 key spirometry indicators; and (f) Predicted flow rate in comparison to ground-truth for two subjects.