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Monitoring of pesticide concentration distribution across farm fields is crucial to ensure precise and efficient application while preventing overuse or untreated areas. 

Abstract The dissemination of sensors is key to realizing a sustainable, ‘intelligent’ world, where everyday objects and environments are equipped with sensing capabilities to advance the sustainability and quality of our lives—e.g. via smart homes, smart cities, smart healthcare, smart logistics, Industry 4.0, and precision agriculture. The realization of the full potential of these applications critically depends on the availability of easy-to-make, low-cost sensor technologies. Sensors based on printable electronic materials offer the ideal platform: they can be fabricated through simple methods (e.g. printing and coating) and are compatible with high-throughput roll-to-roll processing. Moreover, printable electronic materials often allow the fabrication of sensors on flexible/stretchable/biodegradable substrates, thereby enabling the deployment of sensors in unconventional settings. Fulfilling the promise of printable electronic materials for sensing will require materials and device innovations to enhance their ability to transduce external stimuli—light, ionizing radiation, pressure, strain, force, temperature, gas, vapours, humidity, and other chemical and biological analytes. This Roadmap brings together the viewpoints of experts in various printable sensing materials—and devices thereof—to provide insights into the status and outlook of the field. Alongside recent materials and device innovations, the roadmap discusses the key outstanding challenges pertaining to each printable sensing technology. Finally, the Roadmap points to promising directions to overcome these challenges and thus enable ubiquitous sensing for a sustainable, ‘intelligent’ world. 

Open microfluidics have emerged as a low-cost, pumpless alternative strategy to conventional microfluidics for delivery of fluid for a wide variety of applications including rapid biochemical analysis and medical diagnosis. However, creating open microfluidics by tuning the wettability of surfaces typically requires sophisticated cleanroom processes that are unamenable to scalable manufacturing. Herein, we present a simple approach to develop open microfluidic platforms by manipulating the surface wettability of spin-coated graphene ink films on flexible polyethylene terephthalate via laser-controlled patterning. Wedge-shaped hydrophilic tracks surrounded by superhydrophobic walls are created within the graphene films by scribing micron-sized grooves into the graphene with a CO 2 laser. This scribing process is used to make superhydrophobic walls (water contact angle ∼160°) that delineate hydrophilic tracks (created through an oxygen plasma pretreatment) on the graphene for fluid transport. These all-graphene open microfluidic tracks are capable of transporting liquid droplets with a velocity of 20 mm s −1 on a level surface and uphill at elevation angles of 7° as well as transporting fluid in bifurcating cross and tree branches. The all-graphene open microfluidic manufacturing technique is rapid and amenable to scalable manufacturing, and consequently offers an alternative pumpless strategy to conventional microfluidics and creates possibilities for diverse applications in fluid transport. 

Abstract Glyphosate is a globally applied herbicide yet it has been relatively undetectable in‐field samples outside of gold‐standard techniques. Its presumed nontoxicity toward humans has been contested by the International Agency for Research on Cancer, while it has been detected in farmers’ urine, surface waters and crop residues. Rapid, on‐site detection of glyphosate is hindered by lack of field‐deployable and easy‐to‐use sensors that circumvent sample transportation to limited laboratories that possess the equipment needed for detection. Herein, the flavoenzyme, glycine oxidase, immobilized on platinum‐decorated laser‐induced graphene (LIG) is used for selective detection of glyphosate as it is a substrate for GlyOx. The LIG platform provides a scaffold for enzyme attachment while maintaining the electronic and surface properties of graphene. The sensor exhibits a linear range of 10–260µm, detection limit of 3.03µm, and sensitivity of 0.991 nAµm⁻¹. The sensor shows minimal interference from the commonly used herbicides and insecticides: atrazine, 2,4‐dichlorophenoxyacetic acid, dicamba, parathion‐methyl, paraoxon‐methyl, malathion, chlorpyrifos, thiamethoxam, clothianidin, and imidacloprid. Sensor function is further tested in complex river water and crop residue fluids, which validate this platform as a scalable, direct‐write, and selective method of glyphosate detection for herbicide mapping and food analysis.