The unique electronic properties of semiconductor nanowires, in particular silicon nanowires (SiNWs), are attractive for the label-free, real-time, and sensitive detection of various gases. Therefore, over the past two decades, extensive efforts have been made to study the gas sensing function of NWs. This review article presents the recent developments related to the applications of SiNWs for gas sensing. The content begins with the two basic synthesis approaches (top-down and bottom-up) whereby the advantages and disadvantages of each approach have been discussed. Afterwards, the basic sensing mechanism of SiNWs for both resistor and field effect transistor designs have been briefly described whereby the sensitivity and selectivity to gases after different functionalization methods have been further presented. In the final words, the challenges and future opportunities of SiNWs for gas sensing have been discussed.

Flexible electronics is a field gathering a growing interest among researchers and companies with widely varying applications, such as organic light emitting diodes, transistors as well as many different sensors. If the circuit should be portable or off-grid, the power sources available are batteries, supercapacitors or some type of power generator. Thermoelectric generators produce electrical energy by the diffusion of charge carriers in response to heat flux caused by a temperature gradient between junctions of dissimilar materials. As wearables, flexible electronics and intelligent packaging applications increase, there is a need for low-cost, recyclable and printable power sources. For such applications, printed thermoelectric generators (TEGs) are an interesting power source, which can also be combined with printable energy storage, such as supercapacitors. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), or PEDOT:PSS, is a conductive polymer that has gathered interest as a thermoelectric material. Plastic substrates are commonly used for printed electronics, but an interesting and emerging alternative is to use paper. In this article, a printed thermoelectric generator consisting of PEDOT:PSS and silver inks was printed on two common types of paper substrates, which could be used to power electronic circuits on paper.

In this paper, a micrometre thin film of molybdenum disulfide (MoS₂) is characterized for thermoelectric properties. The sample was prepared through mechanical exfoliation of a molybdenite crystal. The Seebeck coefficient measurement was performed by generating a temperature gradient across the sample and recording the induced electrical voltage, and for this purpose a simple measurement setup was developed. In the measurement, platinum was utilized as reference material in the electrodes. The Seebeck value of MoS₂ was estimated to be approximately −600 µV/K at a temperature difference of 40 °C. The negative sign indicates that the polarity of the material is n-type. For measurement of the thermal conductivity, the sample was sandwiched between the heat source and the heat sink, and a steady-state power of 1.42 W was provided while monitoring the temperature difference across the sample. Based on Fourier’s law of conduction, the thermal conductivity of the sample was estimated to be approximately 0.26 Wm⁻¹ K⁻. The electrical resistivity was estimated to be 29 Ω cm. The figure of merit of MoS₂ was estimated to be 1.99 × 10⁻⁴.

Measurements of atmospheric gas concentrations using of NDIR gas sensors requires compensation of ambient pressure variations to achieve reliable result. The extensively used general correction method is based on collecting data for varying pressures for a single reference concentration. This one-dimensional compensation approach is valid for measurements carried out in gas concentrations close to reference concentration but will introduce significant errors for concentrations further away from the calibration point. For applications, requiring high accuracy, collecting, and storing calibration data at several reference concentrations can reduce the error. However, this method will cause higher demands on memory capacity and computational power, which is problematic for cost sensitive applications. We present here an advanced, but practical, algorithm for compensation of environmental pressure variations for relatively low-cost/high resolution NDIR systems. The algorithm consists of a two-dimensional compensation procedure, which widens the valid pressure and concentrations range but with a minimal need to store calibration data, compared to the general one-dimensional compensation method based on a single reference concentration. The implementation of the presented two-dimensional algorithm was verified at two independent concentrations. The results show a reduction in the compensation error from 5.1% and 7.3%, for the one-dimensional method, to −0.02% and 0.83% for the two-dimensional algorithm. In addition, the presented two-dimensional algorithm only requires calibration in four reference gases and the storing of four sets of polynomial coefficients used for calculations.

Hydrogen sulfide (H₂S) is a highly toxic and corrosive gas commonly found in industrial emissions and natural gas processing, posing serious risks to human health and environmental safety even at low concentrations. The early detection of H₂S is therefore critical for preventing accidents and ensuring compliance with safety regulations. This study presents the development of porous ZnO/SnO₂-nanocomposite gas sensors tailored for the ultrasensitive detection of H₂S at sub-ppb levels. Utilizing a screen-printing method, we fabricated five different sensor compositions—ranging from pure SnO₂ to pure ZnO—and characterized their structural and morphological properties through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Among these, the SnO₂/ZnO sensor with a composition-weight ratio of 3:4 demonstrated the highest response at 325 °C, achieving a low detection limit of 0.14 ppb. The sensor was evaluated for detecting H₂S concentrations ranging from 5 ppb to 500 ppb under dry, humid air and N₂ conditions. The relative concentration error was carefully calculated based on analytical sensitivity, confirming the sensor’s precision in measuring gas concentrations. Our findings underscore the significant advantages of mixture nanocomposites in enhancing gas sensitivity, offering promising applications in environmental monitoring and industrial safety. This research paves the way for the advancement of highly effective gas sensors capable of operating under diverse conditions with high accuracy.