A feasible sonochemical method is developed for the complexation of nonsteroidal anti-inflammatory drug ketorolac with the Fe3O4–graphene oxide nanocomposite.

A single-step ultrasonic method (20 kHz) is demonstrated for the formation of acetylsalicylic acid-Fe3O4-graphene oxide nanocomposites (∼80 nm) in aqueous solution. The electronic molecular structure of these nanocomposites is stable in acidic or basic aqueous medium. Coating of these nanocomposites with poly­(vinyl alcohol) (PVA) occurs through increased binding with drug, magnetite, Fe­(II)–C–O and carbonaceous network of graphene oxide. PVA-coated-acetylsalicylic acid-Fe3O4-GO nanocomposites substantially improve acetylation of pristine ascorbic acid than free unmodified drug or uncoated acetylsalicylic acid-Fe3O4-GO nanoparticles because of enhanced electron density through the presence of magnetite and graphene oxide, and specific binding of PVA with drug and ascorbic acid.

The design of the heater plays a decisive role in the energy consumption, sensitivity, and speed of chemical sensors. The paper analyzes various options for the topology of meander-type platinum heaters in chemical sensors fabricated on thin dielectric membranes using MEMS-silicon technology. Comprehensive studies of the heater’s current–voltage characteristics have been carried out, heating rates have been measured at various currents, experimental temperature characteristics for various meander topologies have been obtained, heater options have been determined, and optimal heat transfer processes are ensured at a low power consumption of about 20–25 mW. Sensors with an optimal heater topology based on a double dielectric membrane were fabricated according to the described technological process, and sensory responses to 0.5 vol.% CH4 and 0.2% C3H8 were studied. The obtained results showed good results and confirmed the need to choose the optimal heater topology when designing sensors for recording the given type of gas mixtures in a certain temperature range.