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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.