Robust, Long‐Term, and Exceptionally Sensitive Microneedle‐Based Bioimpedance Sensor for Precision Farming

Abstract

Precision farming has the potential to increase global food production capacity whilst minimizing traditional inputs. However, the adoption and impact of precision farming are contingent on the availability of sensors that can discern the state of crops, while not interfering with their growth. Electrical impedance spectroscopy offers an avenue for nondestructive monitoring of crops. To that end, it is reported on the deployment of impedimetric sensors utilizing microneedles (MNs) that can be used to pierce the waxy exterior of plants to obtain sensitive impedance spectra in open‐air settings with an average relative noise value of 3.83%. The sensors are fabricated using a novel micromolding and release method that is compatible with UV photocurable and thermosetting polymers. Assessments of the quality of the MNs under scanning electron microscopy show that the replication process is high in fidelity to the original design of the master mold and that it can be used for upward of 20 replication cycles. The sensor's performance is validated against conventional planar sensors for obtaining the impedance values of Arabidopsis thaliana. As a change is detected in impedance due to lighting and hydration, this raises the possibility for their widespread use in precision farming.

Microneedles: materials, fabrication, and biomedical applications

“…a A diabetes sensor patch based on hollow biodegradable microneedles (Luo et al 2022 ). b A bioimpedance sensor based on microneedle for precision farming (Bukhamsin et al 2021 ). c A extended gate transistor based on wearable microneedles for real-time detection of sodium in interstitial fluids (Zheng et al 2022 ).…”

Microneedle Sensors for Multiplex Applications: Toward Advanced Biomedical and Environmental Analysis

“…Reproduced with permission. [ 114 ] Copyright 2021, Wiley‐VCH. C) Silk‐MNs‐based phytoinjector and phytosampler that monitors the plant sap for diseases related to plant vasculature.…”

“…The incorporation of MN also mitigates the influence of surrounding noise and electromagnetic interference, demonstrating its potential for in-field applications. [114] Cao et al presented water-soluble and insoluble silk MNs for the applications of phytoinjector and phytosampler by tuning the ratio of silk fibroin (SF) and the derived soluble polypeptides (Cs). Cs 20 SF 80 was preferred for soluble MNs (phytoinjectors) considering its mechanical properties.…”

“…B) MN-based impedimetric sensors that can directly detect crop health status for precision farming. Reproduced with permission [114]. Copyright 2021, Wiley-VCH.…”

Fabrication and Characterization of Porous Microneedles for Enhanced Fluid Injection and Suction: A Two‐Photon Polymerization Approach

“…[10] Rad et al used 2PP to create MNs with intricate microfluidic channels. [9] MNs can fall under the following categories; solid MNs, [24][25][26][27] hollow MNs, [22,28,29] hydrogel MNs, [4,16,17,[30][31][32] dissolving MNs, [19,33,34] and porous MNs. [15,18,35] Although solid MNs are still one of the most commonly used, porous MNs are gaining attention due to their ability to encapsulate a larger amount of fluid as well as act as a filtration system.…”