  The human body is punctuated with wide array of sensory systems that provide
a high evolutionary advantage by facilitating formation of a detailed picture
of the immediate surroundings. The sensors range across a wide spectrum,
acquiring input from non-contact audio-visual means to contact based input via
pressure and temperature. The ambit of sensing can be extended further by
imparting the body with increased non-contact sensing capability through the
phenomenon of electrostatics. Here we present graphene-based tattoo sensor for
proximity sensing, employing the principle of electrostatic gating. The sensor
shows a remarkable change in resistance upon exposure to objects surrounded
with static charge on them. Compared to prior work in this field, the sensor
has demonstrated the highest recorded proximity detection range of 20 cm. It is
ultra-thin, highly skin conformal and comes with a facile transfer process such
that it can be tattooed on highly curvilinear rough substrates like the human
skin, unlike other graphene-based proximity sensors reported before. Present
work details the operation of wearable proximity sensor while exploring the
effect of mounting body on the working mechanism. A possible role of the sensor
as an alerting system against unwarranted contact with objects in public places
especially during the current SARS-CoV-2 pandemic has also been explored in the
form of an LED bracelet whose color is controlled by the proximity sensor
attached to it.
