Table 1.

Comparison with previous surveys.

Year	IoT Wearable Sensors	Health Focus	Contributions of Existing Surveys	Ref.
2018	Body sensors	Glucose, heart rate, blood pressure, body temperature	An intelligent healthcare network using IoThNet topology is discussed.	[10]
2018	SPO2 sensor, BP sensor, EKG sensor, EMG sensor, Motion sensor, Medical super sensor	-	The paper deals with a medical cyber-physical system, networked medical device systems, and IT-based services, emerging medical systems	[11]
2018		Focuses on storing, privacy, and validity of the data that comes through a wearable sensor	This survey provides a comparison of various uses and methods in cloud computing, fog computing, IoT, and embedded systems in healthcare monitoring, interactive healthcare challenges, and the changes that big data analytics has brought on.	[1]
2019	BAN sensors used. Smartwatch sensing the ECG, EMG, and EEG		Survey dedicated to the healthcare monitoring system advancements specifically for chronically patients and the elderly. This includes the environmental sensing around the patients and the measure to detect chronic heart failures.	[12]
2019	-	-	The paper discusses the implementation of ML in resource-scarce embedded systems.	[13]
2019	Smartwatch, smart contact lenses, intelligent asthma management, ingestible sensors, inhalers, activity trackers	EHR, pills, consultation with doctors, overall fitness, health, and healthcare	The survey reviews all the existing devices and systems available and gives a brief overview and function.	[14]
2020	HCMS, e-health	Focuses on monitoring patients accurately. No particular disease stated	Surveys are about the overview of the current tech in the IOTM and the sensors and actuators that can help develop a superior HCMS.	[9]
2020	Blockchain		Survey to point out the usage of blockchain in securing the IoT data.	[4]
2021	-	-	A table is used to summarize that a combination of ML/DL with healthcare IoT and Cloud can be used to solve various security threats	[15]