Among various metal oxides, titanium dioxide (TiO2) has received considerable interest as a gas-sensing material owing to its high reliability at high operating temperatures. Nonetheless, TiO2 generally has low sensitivity to target gases. In particular, TiO2-based sensors have difficulty in sensitively detecting benzene, toluene, and xylene (referred to as BTX). Moreover, the reported TiO2-based sensors have not simultaneously satisfied the demand for tens of ppb BTX detection and operation with low power consumption. This work proposes a BTX sensor using cobalt porphyrin (CoPP)-functionalized TiO2 nanoparticles as a sensing material on a suspended microheater fabricated by bulk micromachining for low power consumption. TiO2 nanoparticles show an enhanced sensitivity (245%) to 10 ppm toluene with CoPP functionalization. The proposed sensor exhibits high sensitivity to BTX at concentrations ranging from 10 ppm down to several ppb. The high reliability of the sensor is also explored through the long-time operation with repeated exposure to 10 ppm toluene for 14 h.

Paper has attracted considerable interest as a promising pressure‐sensing element owing to its foldability/bendability and deformability due to its high porosity. However, paper‐based tactile sensors reported hitherto cannot achieve high sensitivity and a wide sensing range simultaneously. In this study, a resistive tactile sensor using carbon nanotube‐ and silver nanoparticle‐printed mulberry paper as a pressure‐sensing element and electrodes, respectively, is developed. The rough surface and high inner porosity of mulberry paper induce a significant change in the contact area when a multilayer‐stacked structure is used, resulting in increased sensitivity to pressure. Moreover, the enhanced mechanical robustness of mulberry paper originating from the highly bonded network of long and thick fibers affords a wide pressure‐sensing range. The sensor exhibits a high sensitivity exceeding 1 kPa−1 in an applied pressure range of 0.05–900 kPa; this achievement has not been reported among paper‐based tactile sensors. Furthermore, the sensor exhibits a fast response/relaxation time, low detection limit, high resolution, high durability, and high flexibility. The advantages of the sensor afford several applications, including a crosstalk‐free pressure sensor array, a three‐axis pressure sensor, and wearable devices for measuring signals from a user.

A fabrication method for obtaining fine-pored PDMS is presented. Low-cost, volatile, and easily accessible IPA is used as a co-solvent in water and PDMS emulsions, allowing porous PDMS with adjustable mechanical, optical and thermal properties.

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