Strain-Sensor-In-Pixel Technology for Resolution-Sustainable Stretchable Displays

One of the limitations of stretchable displays is the
severe degradation
of resolution or the decrease in the number of pixels per unit area
when stretched. Hence, we suggest a strain-sensor-in-pixel (S-SIP)
system through the adoption of hidden pixels that are activated only
during the stretch mode for maintaining the density of on-state pixels.
For the S-SIP system, the gate and source electrodes of InGaZnO thin-film
transistors (TFTs) in an existing pixel are connected to a resistive
strain sensor through the facile and selective deposition of silver
nanowires (AgNWs) via electrohydrodynamic-jet-printing. With this
approach, the strain sensor integrated TFT functions as a strain-triggered
switch, which responds only to stretching along the designated axes
by finely tuning the orientation and cycles of AgNW printing. The
strain sensor-integrated TFT remains in an off-state when unstretched
and switches to an on-state when stretched, exhibiting a large negative
gauge factor of −1.1 × 1010 and a superior
mechanical stability enduring 6000 cycles, which enables the efficient
structure to operate hidden pixels without requiring additional signal
processing. Furthermore, the stable operation of the S-SIP in a 5
× 5-pixel array is demonstrated via circuit simulation, implying
the outstanding applicability and process compatibility to the conventional
active-matrix display backplanes.