Oxide semiconductor based deep-subthreshold operated read-out
electronics for all-printed smart sensor patches
Abstract
The ability to fabricate an entire smart sensor patch with read-out
electronics using commercial printing techniques may have a wide range
of potential applications. Although the solution-processed oxide thin
film transistors (TFTs) are capable of providing high mobility electron
transport, resulting in large ON-state current and power output, there
is hardly any literature report that uses the printed oxide TFTs, at the
sensor interfaces. In contrast, here we propose and demonstrate that
printed amorphous indium-gallium-zinc oxide (a-IGZO) based
deep-subthreshold operated TFTs can be used to fabricate an entire
sensor analog front-end electronics comprising signal amplifiers, and
analog-to-digital converters (ADCs), which can successfully digitalize
the analog sensor signal up to frequency range of 1 kHz. In addition,
exploiting the high current oxide TFTs, a current drive circuit has been
designed, and placed after the ADC unit. This current drive circuit is
essential to offer sufficient power output, which can then be used to
fabricate an easy-to-detect visual recognition of the sensor signal at a
predefined threshold value crossover. Notably, the entire smart sensor
patch is demonstrated to operate at a low supply voltage of ≤2 V,
thereby ensuring that it can be an on-chip, energy source compatible,
and standalone detection unit.