Table 1.

Comprehensive comparison between other flexible real-time glucose monitoring systems and the proposed sensor.

References	Sensing technique	Focused material	Sampling method	Sensor substrate	Comments
21	Electrochemical sensor	ISF	Transdermal ISF extraction using reverse-iontophoresis process	Flexible PET sheet	Flexible and wearable structure Semi-invasive The target fluid is available upon the reverse iontophoresis extraction process High saturability
50	Resistance and capacitance variations of an electronic device	Tear	Tear is available	500 nm thick Parylene	Wearable but hard to implant Semi-invasive Complex structure Target fluid availability is high No-saturability
51	Electrochemical sensor	ISF	Transdermal extraction and collection of ISF using an extraction chip	Flexible polyimide substrate	Flexible and wearable structure Semi-invasive based on ISF extraction chip Availability of the target fluid is low for the sensor High-saturability
52	Electrochemical sensor	Sweat	Sweat collection using an ultrathin and stretchable design	Flexible polyimide substrate	Flexible and wearable structure Non-invasive Availability of the target fluid is low and require heating and/or electrical excitation High saturability
53	Near-infrared transmission spectroscopy	Blood	No-extraction is required	NA	Claimed wearable but not flexible Complicated structure Non-invasive The target fluid is always available No-saturability Low precision
This work	Microwave resonator	ISF	No-extraction is required	Flexible ultra-thin dielectric substrate	Flexible and wearable structure Non-invasive The target fluid is always available No-saturability Lower precision