“Heterogeneous Integration” is a promising approach for high‐performance hybrid flexible electronics that combine printed electronics and silicon technology. Despite significant progresses made by integrating rigid silicon chips on flexible substrates, the integration of flexible ultra‐thin chips (UTCs) on flexible foils remains a challenge as they are too fragile for conventional bonding methods. Reliable interconnects (low‐resistivity and mechanical robustness) and bonding of UTCs are critical to the realization of hybrid flexible systems. Herein, using a non‐contact printing approach, an easy and cost‐effective method for accessing UTCs on flexible foils is demonstrated. The high‐viscosity conductive paste, extruded from a high‐resolution printer (1–10 µm line width), is used here to connect the metal oxide semiconductor field effect transistors (MOSFETs) on UTCs with the extended pads on flexible printed circuit boards (PCBs). The electrical characterization of MOSFETs, before and after printing the interconnects, reveals an acceptable level of variation in device mobility (change from 780 to 630 cm2 V−1s−1). This is due to the drop in effective drain bias voltage as a marginally small electrical resistance (≈30 Ω) is added by the printed interconnects. The bonded UTCs show robust device performance under bending conditions, indicating high reliability of both the chip thinning and bonding methods.

Fully aromatic conjugated covalent organic frameworks (FAC‐COFs) with excellent physicochemical stability have been emerging as active semiconductors for diverse potential applications. Developing efficient synthesis methods for fabricating FAC‐COFs will significantly facilitate the exploration over their material and photonic/electronic functionalities. Herein, a facile solvent‐free strategy is developed for the synthesis of 2D phthalocyanine‐based FAC‐COFs (FAC‐Pc‐COFs). Cyclopolymerization of benzo[1,2‐b:4,5‐b′]bis[1,4]benzodioxin‐2,3,9,10‐tetracarbonitrile (BBTC) and quinoxalino[2′,3′:9,10]phenanthro[4,5‐abc]phenazine‐6,7,15,16‐tetracarbonitrile (QPPTC) in ZnCl2 leads to the fast formation and isolation of BB‐FAC‐Pc‐COF and QPP‐FAC‐Pc‐COF, respectively. Powder X‐ray diffraction and electron microscopy analysis reveal their crystalline nature with sql topology and AA stacking configuration. Thermogravimetric analysis and immersion experiment indicate their excellent stability. The conductivity test demonstrates their high conductivity of 0.93–1.94 × 10−4 S cm−1 owing to the fully π‐conjugated electronic structural nature. In particular, the as‐prepared FAC‐Pc‐COFs show high‐performance K+ storage in potassium‐ion batteries due to their excellent conductivity, highly ordered and robust structure, and N/O‐rich framework nature. Impressively, QPP‐FAC‐Pc‐COF shows a large reversible capacity of 424 mA h g−1 after 100 cycles at 50 mA g−1 and a capacity retention of nearly 100% at 2000 mA g−1 for over 10 000 cycles.

Highly sensitive capacitive pressure sensors with wide detection range are needed for applications such as humanmachine interfaces, electronic skin in robotics, and health monitoring. However, it is challenging to achieve high sensitivity and wide detection range at the same time. Herein, we present an innovative approach to obtain a highly sensitive capacitive pressure sensor by introducing a zinc oxide nanowire (ZnO NW) interlayer at the polydimethylsiloxane (PDMS)/electrodes interface in the conventional metal-insulator-metal architecture. The ZnO NW interlayer significantly enhanced the performance with ~7 times higher sensitivity (from 0.81 %kPa -1 to 5.6452 %kPa -1 at a low-pressure range (0-10 kPa)) with respect to conventional capacitive sensors having PDMS only as the dielectric. The improvement in sensitivity is attributed to the enhanced charge separation and electric dipole generation due to the displacement of Zn + and Ounder applied pressure. Further, the orientation of ZnO NWs and their placement between the electrodes were investigated which includes either vertical or horizontal NWs near the electrodes, placing a third ZnO NW interlayer in the middle of dielectric PDMS and introducing an air gap between the ZnO NWs/electrode. Among various combinations, the introduction of air gap between the electrode and ZnO NW interlayer revealed a significant improvement in the device performance with ~50 times enhancement at a low-pressure range (0-10 kPa) and more than 200 times increase at a high-pressure range (10-200 kPa), in comparison with the conventional PDMS-based pressure sensor.

This paper presents ultrathin chips (UTCs) based flexible tactile sensing system for dynamic contact pressure measurement. The device comprises of an AlN piezocapacitor based UTCs tightly coupled with another UTCs having metaloxide-semiconductor field-effect transistors (MOSFETs). In this arrangement the AlN piezocapacitor forms the extended gate of MOSFETs. Both AlN piezocapacitor and MOSFET based UTCs are obtained by post-process reduction of wafer thicknesses to ~35µm using backside lapping. The performances of both UTCs were evaluated both before and after thinning and there was no noticeable performance degradation. The UTC-based AlN piezocapacitor exhibited six times higher sensitivity (43.79mV/N) than the thin filmbased AlN sensors. When coupled with MOSFETs based UTC, the observed sensitivity was 0.43N -1 . The excellent performance, flexible form factor and compactness shows the potential of presented device in applications such minimal invasive surgical instruments where high-resolution tactile feedback is much needed.

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