School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA.
Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA.
Sci Rep. 2022 May 14;12(1):8011. doi: 10.1038/s41598-022-12162-z.
Precision Agriculture (PA) is an integral component of the contemporary agricultural revolution that focuses on enhancing food productivity in proportion to the increasing global population while minimizing resource waste. While the recent advancements in PA, such as the integration of IoT (Internet of Things) sensors, have significantly improved the surveillance of field conditions to achieve high yields, the presence of batteries and electronic chips makes them expensive and non-biodegradable. To address these limitations, for the first time, we have developed a fully Degradable Intelligent Radio Transmitting Sensor (DIRTS) that allows remote sensing of subsoil volumetric water using drone-assisted wireless monitoring. The device consists of a simple miniaturized resonating antenna encapsulated in a biodegradable polymer material such that the resonant frequency of the device is dependent on the dielectric properties of the soil surrounding the encapsulated structure. The simple structure of DIRTS enables scalable additive manufacturing processes using cost-effective, biodegradable materials to fabricate them in a miniaturized size, thereby facilitating their automated distribution in the soil. As a proof-of-concept, we present the use of DIRTS in lab and field conditions where the sensors demonstrate the capability to detect volumetric water content within the range of 3.7-23.5% with a minimum sensitivity of 9.07 MHz/%. Remote sensing of DIRTS can be achieved from an elevation of 40 cm using drones to provide comparable performance to lab measurements. A systematic biodegradation study reveals that DIRTS can provide stable readings within the expected duration of 1 year with less than 4% change in sensitivity before signs of degradation. DIRTS provides a new steppingstone toward advancing precision agriculture while minimizing the environmental footprint.
精准农业（PA）是当代农业革命的一个组成部分，其专注于在提高粮食产量以应对不断增长的全球人口的同时，最大限度地减少资源浪费。尽管最近在 PA 方面的进展，如物联网（IoT）传感器的集成，已经极大地改善了对田间条件的监测，以实现高产量，但电池和电子芯片的存在使它们变得昂贵且不可生物降解。为了解决这些限制，我们首次开发了一种完全可降解的智能无线电发射传感器（DIRTS），它允许使用无人机辅助无线监测来远程感知亚表层体积含水量。该设备由一个简单的小型谐振天线封装在可生物降解的聚合物材料中，使得设备的谐振频率取决于封装结构周围土壤的介电特性。DIRTS 的简单结构允许使用具有成本效益的可生物降解材料进行可扩展的增材制造工艺，从而以小型化的尺寸制造它们，并促进它们在土壤中的自动分布。作为概念验证，我们在实验室和现场条件下展示了 DIRTS 的使用，其中传感器能够在 3.7-23.5%的范围内检测体积含水量，最小灵敏度为 9.07 MHz/%。可以使用无人机从 40 cm 的高度进行 DIRTS 的远程感应，从而提供与实验室测量相当的性能。系统的生物降解研究表明，DIRTS 可以在预期的 1 年时间内提供稳定的读数，在出现降解迹象之前，灵敏度的变化小于 4%。DIRTS 为推进精准农业提供了新的起点，同时最大限度地减少了对环境的影响。
