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Graphene has amazing applications for sensors due to its excellent performances like high strength and good conductivity, but the transfer issue is in the way of its application perspective. Direct growth of spherical graphene films (SGFs) on cemented carbide may offer a good avenue for various applications in sensor technology, especially for electrochemical sensors. Four common methods for graphene preparation are chemical stripping, chemical vapor deposition (CVD), metal catalysis, and laser fabrication; and subject to transfer issues during usage. In order to overcome this limitation, the fabrication of in-situ growth of SGFs on carbide is proposed as a solution for constructing sensor matrices. This review explores various in-situ SGFs and their potential applications in sensors. The findings presented here shed light on transfer-free graphene with controllable structures that can serve as excellent candidates for sensor matrices.

In this work, the potential of tin (IV) 2,3-napthalocyanine dichloride (SnNcCl₂) has been studied for sensing applications due to its hydrophobic nature. The multipurpose sensor was fabricated by depositing 50-nm silver (Ag) electrodes on a glass substrate through vacuum thermal evaporation at pressure of $\sim 10^{-5}$ mbar. With the help of masking, a 40-micron inter-electrode gap between Ag electrodes was developed and then 80-nm film of SnNcCl₂ was thermally deposited in the inter-electrode gap resulting in a surface type Ag/SnNcCl₂/Ag multipurpose sensor and was studied for humidity and temperature sensing. The humidity characterization was carried out at two different frequencies, i.e. 120 and 1kHz in the relative humidity range 35–85% RH and 5.5 and 1.3 times increase was recorded with respect to initial capacitance for both frequencies, respectively. The temperature sensing was studied within a temperature range of 15–80^∘C at 120Hz frequency and 1.3 times increase in capacitance was observed with respect to initial capacitance. The sensor’s important parameters, i.e. response time and recovery time were measured to be 8 and 3s at 120Hz for humidity measurements. The morphology of the SnNcCl₂ thin film was measured by atomic force microscope (AFM) and scanning electron microscope (SEM) showing rough surface favorable for sensing applications. The amorphous structure of the film was confirmed by X-ray diffraction (XRD) while optical bandgap was calculated from ultraviolet-visible (UV-vis) spectroscopy.

Film bulk acoustic wave resonator (FBAR) experienced skyrocketing development in the past 15 years, owing to the explosive development of mobile communication. It stands out in acoustic filters mainly because of high quality factor, which enables low insertion loss and sharp roll off. Except for the massive application in wireless communication, FBARs are also promising sensors because of the high sensitivity and readily integration ability to miniaturize circuits. On the ground of summarizing FBAR’s application in wireless communication as filters and in sensors including electronic nose, bio field, and pressure sensing, this paper review the main challenges of each application faced. The number of filters installed in the mobile phone has being grown explosively, which leads to overcrowded bands and put harsh requirements on component size and power consumption control for each unit. Data flow and rate are becoming increasingly demanding as well. This paper discusses three promising technical strategies addressing these issues. Among which coupled resonator filter is given intense attention because it is able to vigorously reduce the filter size by stacking two or more resonators together, and it is a great technique to increase data flow and rate. Temperature compensation methods are discussed considering their vital influence on frequency stability. Finally, materials improvement and novel materials exploration for band width modulation, tunable band acquisition, and quality factor improvement are discussed. The authors appeal attention of the academic society to bring AlN epitaxial thin film into the FBAR fabrication and have proposed a configuration to implement this idea.

We demonstrate here a facile and effective strategy to prepare reduced graphene oxide-platinum nanoparticle (RGO-PtNP) nanohybrids by the mediation of graphite-specific peptide (GSP). For the first time, we found that GSP can be used to modify RGO non-covalently in one way, and in another way promote the formation of PtNPs on RGO as a biomolecular bridge. The created RGO-PtNP nanohybrids show enhanced electrocatalytic activity toward H₂O₂ and can be utilized to fabricate non-enzymatic electrochemical H₂O₂ sensor.

The hollow nanoarrays have great potential in both communication systems and monochromatic light conduction. At present, how to prepare the hollow nanoarrays quickly and efficiently is still a challenge. In this work, we introduce a kind of nanoarray supported by carbon nanotubes and oriented stretching by instantaneous Joule heating. The hollow nanoarrays have a small diameter, and are expected to enable single-mode transmission of light source signals, as well as the prospect of application in monochromatic photocatalysis. Therefore, the obtained hollow nanoarrays have a wide range of application prospects in the field of information transmission, catalysis and sensor.

Er³⁺ and Yb³⁺ co-doped CaBi₂Ta₂O₉ (CBT)-based bismuth layered-structure oxides were synthesized by a simple solid-state reaction method. Their up-conversion (UC) luminescence, dielectric and ferroelectric properties were investigated. Two strong green emission bands centered at 526 and 547 nm and a weak red emission band centered at 658 nm were obtained under a 980 nm laser excitation at room temperature. These emission bands originated from the radiative relaxation of Er³⁺ from ²H_11/2, ⁴S_3/2, and ⁴F_9/2 levels to the ground state ⁴I_15/2, respectively. At the meantime, the fluorescence intensity ratio (FIR) variation of two green UC emissions at 526 and 547 nm has been studied as a function of temperature in the range of 153–603 K. The maximum sensor sensitivity obtained was 39 × 10^-4 K^-1 at 590 K, which indicated that Er³⁺/Yb³⁺ co-doped CBT ceramic is a promising candidate for applications in optical high temperature sensor.