Handheld Crop Pest Sensor Using Binary Catalyst-Loaded Nano-SnO₂ Particles for Oxidative Signal Amplification

Abstract

In agriculture, pest management is a major challenge. Crop releases volatiles in response to the pest; hence, sensing these volatile signals at a very early stage will ease pest management. Here, binary catalyst-loaded SnO 2 nanoparticles of <5 nm were synthesized for the repeated capture and oxidation of the signature volatile and its products to amplify the chemoresistive signal to detect concentrations as low as ≈120 ppb. The sensitivity may be due to the presence of the elements in the Sn−Fe−Pt bond evidenced by extended X-ray absorption fine-structure spectroscopy (EXAFS) that captures and oxidize the volatile without escaping. This strong catalyst may oxidize nontarget volatiles and can cause false signals; hence, a molecular sieve filter has been coupled to ensure high selectivity for the detection of Tuta absolutainfestation in tomato. Finally, with the support of a mobile power bank, the optimized sensor has been assembled into a lightweight handheld device.

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“…Following the material confirmation through the above characterization, the synthesized material (≈5 mg) was dropcasted on sensor electrodes, with reference to our previous optimization. 51,52 To obtain maximum sensitivity, an electrode having a 200 μm interdigit gap and a platinum heating electrode at the back for temperature control have been used. Following this, the electrodes were stabilized thermally in a furnace at ≈500 °C for ≈5 hours.…”