Field effect transistor-based tactile sensors: From sensor configurations to advanced applications

The past several decades have witnessed great progress in high-performance field effect transistors(FET)as one of the most important electronic compo-nents.At the same time,due to their intrinsic advantages,such as multiparameter accessibility,excellent electric signal amplification function,and ease of large-scale manufacturing,FET as tactile sensors for flexible wear-able devices,artificial intelligence,Internet of Things,and other fields to per-ceive external stimuli has also attracted great attention and become a significant field of general concern.More importantly,FET has a unique three-terminal structure,which enables its different components to detect external mechanics through different sensing mechanisms.On one hand,it provides an important platform to shed deep insights into the underlying mechanisms of the tactile sensors.On the other hand,these properties could in turn endow excellent components for the construction of tactile matrix sensor arrays with high quality.With special emphasis on the configuration of FETs,this review classified and summarized structure-optimized FET tactile sensors with gate,dielectric layer,semiconductor layer,and source/drain electrodes as sensing active components,respectively.The working principles and the state-of-the-art protocols in terms of high-performance tactile sensors are detail discussed and highlighted,the innovative pixel distribution and integration analysis of the transistor sensor matrix array concerning flexible electronics are also intro-duced.We hope that the introduction of this review can provide some inspiration for future researchers to design and fabricate high-performance FET-based tactile sensor chips for flexible electronics and other fields.

PDMS/MWCNT-based tactile sensor array with coplanar electrodes for crosstalk suppression

The severe crosstalk effect is widely present in tactile sensor arrays with a sandwich structure.Here we present a novel design for a resistive tactile sensor array with a coplanar electrode layer and isolated sensing elements,which were made from polydimethylsiloxane(PDMS)doped with multiwalled carbon nanotubes(MWCNTs)for crosstalk suppression.To optimize its properties,both mechanical and electrical properties of PDMS/MWCNT-sensing materials with different PDMS/MWCNT ratios were investigated.The experimental results demonstrate that a 4 wt% of MWCNTs to PDMS is optimal for the sensing materials.In addition,the pressure-sensitive layer consists of three microstructured layers(two aspectant PDMS/MWCNT-based films and one top PDMS-based film)that are bonded together.Because of this three-layer microstructure design,our proposed tactile sensor array shows sensitivity up to−1.10 kPa^(−1),a response time of 29 ms and reliability in detecting tiny pressures.