This thesis aims to enable the development of a heterostructure composed of gallium nitride (GaN) thin films and carbon black-derived flash graphene (CBFG) and/or poly(o-methoxyaniline) (POMA), with the intention of utilizing it in sensing applications. This work includes the deposition of GaN thin films through sputtering on Si(100) and glass substrates, the synthesis of CBFG and POMA powders via flash Joule heating (FJH) system and oxidative polymerization, respectively, and the fabrication and optimization of an ink containing CBFG, POMA, or both. In surface acoustic wave (SAW) devices, GaN film can be used as the piezoelectric substrate, and the ink can be applied as the sensing layer in the sensor's active area. The results showed successful deposition of GaN films on Si and glass by sputtering. X-ray diffraction (XRD), Raman spectroscopy measurements, and transmission electron microscopy (TEM) image confirmed that the GaN films are polycrystalline and exhibit wurtzite crystal structure with preferential orientation in the c-direction. The values of H/? (thickness/wavelength) obtained using the thickness measured by scanning electron microscopy (SEM) (2h ' H = 329 ± 17 nm, ? = 1000 nm ' H/? = 0.33 | 4h ' H = 569 ± 30 nm, ? = 1000 nm ' H/? = 0.57 | 6h ' H = 1162 ± 36 nm, ? = 1000 nm ' H/? = 1.16) showed that the GaN sample grown for 6 hours, even though exhibiting a high root mean square (RMS) roughness measured by atomic force microscopy (AFM), should still demonstrate the best performance in SAW applications. An ohmic contact between the interdigitated transducers (IDTs) and GaN film was observed, which is beneficial for SAW device applications. SAW devices were produced and optimized using the deposited GaN on Si films. Pure turbostratic CBFG was successfully synthesized using the FJH system, as confirmed by XRD, SEM, and TEM images. Porosimetry analysis showed CBFG's surface area around 293 m² g?¹. As a result, CBFG proved to be a promising adsorbent for methylene blue (MB) removal, which is an intriguing property for enhancing the sensitivity of the device. POMA was successfully synthesized through oxidative polymerization, as supported by XRD and XPS results. Fourier transform infrared spectroscopy (FTIR) data showed amine and imine units on the polymer chain of POMA, consistent with XPS analysis. SEM images depicted material with a globular morphology, while the porosimetry presented a surface area around 4 m² g?¹. Despite its low surface area in comparison to CBFG, POMA remains a potential material for composing a conductive ink due to its chemical surface, and dispersibility, facilitating the ink production process and retaining the electron conductivity (EC) properties. CBFG and POMA powders were combined in various ratios to form an ink with suitable EC. The highest EC value of 0.768 S m-1 was achieved using concentrations of 40.0 mg L-1 CBFG, 2.0 mg L-1 POMA, and 4.0 mg L-1 binder. This result suggests that the ink can be effectively utilized as a sensing layer in the active area of a SAW device.