Table 1.

A comparison between different wearable blood pressure estimation studies and devices

Year	Author	Wearable type	Sensors	Transmission mode	# Subjects	f	r (f,SBP)
2019	Redha et al.56	Wristband	PPG	N/R	n1 = 106	Feature set	0.69
2017	Holz et al.53	Eyeglass frame and finger probe	PPG	N/R	n1 = 4	PTT	0.64–0.84
2017	Zhang et al.43	Armband	ECG and PPG	USB cable	n1 = 10	PAT	N/R
2016	Plante et al.50	Mobile phone (camera + microphone)	Heart sound and PPG	N/R	n1 = 85	VTT	≈0.4
2016	Seeberg et al.44	Chest belt	ECG and PPG	Bluetooth	n1 = 16	PTT	−0.56
2016	Griggs et al.42	Bicep- and wrist-worn device	ECG and PPG	Radio frequency	n1 = 8	PAT	−0.7
2016	Zheng et al.17	Armband	ECG and PPG	Bluetooth	n1 = 9, n2 = 15	PAT	N/R
2015	Munnoch and Jiang79	Handheld	ECG and PPG	Bluetooth	n1 = 2	PAT	N/R
2014	Jung et al.39	Finger probe and chest pad	ECG and PPG	Bluetooth	N/R	PAT	N/R
2014	Thomas et al.80	Wrist watch	ECG and PPG	Bluetooth	N/R	PAT	−0.55
2012	Miao et al.81	Portable device	ECG and PPG	Bluetooth	N/R	N/R	N/R
2009	Guo et al.40	Wrist watch and finger probe	ECG and PPG	ZigBee	N/R	PAT	N/R
2008	Pandian et al.45	Vest-worn device	ECG and PPG	Radio frequency	n1 = 25	PAT	N/R

r Pearson’s correlation coefficient, f PPG-based feature(s), N/R not reported, n₁ number of healthy subjects, n₂ number of hypertensive subjects, PAT pulse arrival time, PTT pulse transit time, VTT vascular transit time