Health is wealth. Thus, it is very important to keep it healthy all the time for sustenance of human livelihood. Last decade has witnessed a number of digital developments, including sensors, microcontrollers, communication paradigm, and smarter societal need. Internet of Things (IoT) has pushed the human race toward harnessing of truly digitized e-healthcare services mainly by relying over the biosensors. Biosensors play most crucial role in IoT when question of e-healthcare comes into the scene. A range of sensors are available in market that help people to monitor daily fitness, blood glucose level and many smart home-based diagnostics. However, lack of proper categorization of such sensors has led to create problems like delay in government approval, gap in patient–doctor​ relationship, increased social inertia toward using the sensors in accordance to regular life style. To mitigate these issues, this work presents a systematic review on existing IoT-based sensors and IoT-market cap originated sensor-systems for taxonomically representation. We present comparative analysis among the reviewed sensors. We further present security and privacy issues associated with the sensor data and ways to mitigate them. We also discuss about futuristic plans to enhance current scenario. We further elaborate on how such intervention could be beneficial or problematic for society. We can conclude that IoT-based sensors upon certain fixation in terms of categorization and proper orientation can be very useful to make a smarter human society.