The precise monitoring of environmental contaminants and agricultural plant stress factors, respectively responsible for damages to our ecosystems and crop losses, has nowadays become a topic of uttermost importance. This is also highlighted by the recent introduction of the so-called “Sustainable Development Goals” of the United Nations, which aim at reducing pollutants while implementing more sustainable food production practices, leading to a reduced impact on all ecosystems. In this context, the standard methods currently used in these fields represent a sub-optimal solution, being expensive, laboratory-based techniques, and typically requiring trained personnel with high expertise. Recent advances in both biotechnology and material science have led to the emergence of new sensing (and biosensing) technologies, enabling low-cost, precise, and real-time detection. An especially interesting category of biosensors is represented by field-effect transistor-based biosensors (bio-FETs), which enable the possibility of performing in situ, continuous, selective, and sensitive measurements of a wide palette of different parameters of interest. Furthermore, bio-FETs offer the possibility of being fabricated using innovative and sustainable materials, employing various device configurations, each customized for a specific application. In the specific field of environmental and agricultural monitoring, the exploitation of these devices is particularly attractive as it paves the way to early detection and intervention strategies useful to limit, or even completely avoid negative outcomes (such as diseases to animals or ecosystems losses). This review focuses exactly on bio-FETs for environmental and agricultural monitoring, highlighting the recent and most relevant studies. First, bio-FET technology is introduced, followed by a detailed description of the the most commonly employed configurations, the available device fabrication techniques, as well as the specific materials and recognition elements. Then, examples of studies employing bio-FETs for environmental and agricultural monitoring are presented, highlighting in detail advantages and disadvantages of available examples. Finally, in the discussion, the major challenges to be overcome (e.g., short device lifetime, small sensitivity and selectivity in complex media) are critically presented. Despite the current limitations and challenges, this review clearly shows that bio-FETs are extremely promising for new and disruptive innovations in these areas and others.

The integration of mechanical metamaterials with sensor technology has opened new frontiers in the design and application of advanced sensing systems due to their ability to impart unique mechanical properties that enhance sensor functionality. Mechanical metamaterials, with properties derived from their engineered structures rather than their material composition, offer unique advantages such as negative Poisson’s ratio, high strength-to-weight ratios, and programmable behaviors. This review explores the dual approaches of incorporating sensors with mechanical metamaterials: metamaterial-supported sensors, where metamaterials provide structural support and enhanced durability to traditional sensors, and metamaterial-integrated sensors, where the metamaterial itself serves as the sensing element. Incorporating metamaterials in sensor design can offer increased sensitivity and precision, enhanced structural integrity and durability, programmability and reconfigurability, as well as lightweight and compact design solutions. Key advancements in the field are presented, highlighting how metamaterials properties can enhance sensor performance in terms of sensitivity, precision, and operational versatility. The review covers the primary materials and fabrication techniques used, including additive manufacturing, molding, and physical vapor deposition, and discusses the challenges associated with the mechanical integration of metamaterials and sensors. Practical applications in pressure, strain, temperature, and biomedical sensing are examined, demonstrating the transformative potential of mechanical metamaterials in creating high-performance, multifunctional sensor systems. The discussion concludes with an outlook on future research directions and potential advancements in the field.

This letter presents a monolayer onion epidermis as an ultra-thin substrate for the development of dry electrodes used in electrical impedance spectroscopy (EIS), offering biocompatibility, flexibility, and high fidelity. The dry electrode is fabricated by sputtering a 100 nm layer of molybdenum (Mo) onto the hydrophilic side of the epidermis membrane. Optical characterization confirms the structural integrity and quality of the thin metal film. Electrical characterization reveals a low sheet resistance of 151.28 ±0.08 Ω/sq.m, and experimental EIS studies demonstrate the electrode's enhanced electrical characteristics and capability to acquire impedance spectra from various fruits. Additionally, durability tests over six months show comparable performance to commercial electrodes. This biocompatible electrode offers a promising, cost-effective and sustainable solution with reduced resource utilization, ideal for agrifood and wearable electronics applications.

Biosensors are analytical devices used to detect the presence of a specific bio-chemical substance (called analyte), through the combination of a biorecognition element with a physico-chemical transducer. Biosensors using field-effect transistor (FET) transducing platforms (called Bio-FETs) exploit the variations of the current between a source and a drain terminal upon specific (physical or chemical) interactions in presence of the analyte of interest. While Bio-FETs have mainly been used in various fields of application such as medical diagnostics, bio-molecule detection (like glucose) and food safety, environmental monitoring is still a quite unexplored area. In particular for agricultural applications, it is extremely important to develop real-time, portable, and low-cost monitoring devices for various types of pesticides, especially considering that nowadays many of these are considered environmental contaminants and are being banned. Only recently some studies have reported the development of Bio-FETs for the detection of a particular type of pesticides: herbicides. In this review, we revise the use of Bio-FETs for environmental monitoring applications. First we highlight the working principles of Bio-FETs, presenting the most commonly used material and the possible device configurations. Then we present the most relevant studies employing Bio-FETs for environmental monitoring. Finally, we show a quite new approach for Bio-FET, which is the coupling of biosensors with artificial intelligence and machine learning algorithms, to analyse complex data.