The field’s foundation rests on a remarkable class of substances known as two-dimensional materials: crystals that are only one or a few atoms thick yet can span vast lateral areas. Graphene, the honeycomb lattice of carbon atoms that pioneered the field, remains the most famous example, but the modern catalogue is far larger. Hundreds of such materials have already been experimentally validated and thousands more have been theoretically predicted, ranging from transition-metal dichalcogenides such as molybdenum disulfide to hexagonal boron nitride, elemental X-enes, black phosphorus, MXenes and more. Each brings a different combination of electrical, mechanical, geometrical and chemical properties that can be matched to specific sensing tasks.

The technical appeal of these atomically thin channels for biosensing stems from their geometry and their physics. Because every atom in a two-dimensional material lies at the surface, the entire conduction path is exposed to the surrounding environment. When a biomolecule binds to the surface of a transistor built from such a material, it directly perturbs the flow of charge carriers through the channel, shifting the device’s transfer characteristics in a measurable way. This direct coupling between molecular recognition and charge transport is what enables amplification-free, label-free detection at extraordinary sensitivity, in some devices reaching femtomolar detection limits without enzymes, fluorophores or polymerase chain reaction.

Graphene has led the way. Its exceptional carrier mobility, quantum capacitance, mechanical flexibility and chemical stability have produced electrolyte-gated field-effect transistors capable of detecting pH changes, protein adsorption, DNA, viruses and biomarkers in physiological fluids. Antibody-functionalized graphene transistors have detected SARS-CoV-2 directly in clinical nasopharyngeal swabs without amplification, and flexible graphene electronic tattoos have continuously tracked arterial blood pressure and mapped cortical brain activity wirelessly. Operating graphene transistors near the charge neutrality point, where conductivity is at a minimum and low-frequency noise is favorable, maximizes sensitivity and has clarified how ionic Debye screening constrains signal transduction in salt-rich environments such as blood and sweat.

Yet the authors argue that graphene is only the beginning. Transition-metal dichalcogenides offer a distinct trade-off: unlike gapless graphene, their semiconducting bandgaps allow transistor channels to be fully switched off, reducing background current and enabling different operating regimes. Molybdenum disulfide transistors have detected nucleic acids and proteins with femtomolar sensitivity, and the metallic 1T phase of these materials supports fast heterogeneous electron transfer for enzyme-based electrochemical sensing. Phase engineering, in which the atomic arrangement of the material is switched between semiconducting and metallic forms, adds a further design lever. Beyond the dichalcogenides, black phosphorus brings a tunable gap that varies with layer thickness, indium selenide field-effect transistors have rapidly identified SARS-CoV-2 variants, platinum dichalcogenides have yielded reusable ultrathin electronic tattoos, and MXenes contribute metallic conductivity and rich surface chemistry for biosensing composites.

A recurring theme of the Perspective is that in real devices, structural and chemical variability often outweighs intrinsic material properties in determining performance. Defects, grain boundaries, surface terminations, adsorbed contamination and variations in layer thickness all scatter charge carriers, shift the charge neutrality point and introduce noise and hysteresis. Two nominally identical devices can behave quite differently because of fabrication-related differences invisible to the naked eye. The authors contend that further progress will depend on linking biosensing performance more directly to the intrinsic structures and properties of individual materials, so that sensitivity and stability become predictable design outcomes rather than empirical surprises from batch to batch.

Equally decisive is the biofunctionalization strategy, the chemistry that connects the sensor surface to the biological world. Covalent attachment of receptors provides durable immobilization but can degrade the electronic properties of the underlying channel; non-covalent approaches based on pyrene linkers or supramolecular interactions preserve the lattice while anchoring antibodies, aptamers or enzymes, but may be less stable over time. The choice of linker chemistry and receptor controls the sensor’s stability, drift and usable lifetime. Structure-switching aptamers have even allowed small-molecule detection to overcome the Debye length limitation, by transducing binding-induced charge redistribution close to the channel, and wearable aptamer transistors have achieved non-invasive, continuous cortisol monitoring from sweat. Emerging tools such as CRISPR-Cas9 immobilized on graphene transistors, epitope-imprinted surfaces and DNA origami architectures extend molecular selectivity still further.

The authors are candid about the field’s persistent weaknesses. Sensitivity alone is no longer sufficient; devices must also deliver selectivity against interfering species, reproducibility across laboratories, minimal baseline drift during long-term operation and stable performance under physiological conditions, including high ionic strength, temperature and protein-rich media. Noise sources such as charge traps and adsorbed water, hysteresis in transfer characteristics and gradual surface fouling all degrade real-world reliability. The diversity of two-dimensional materials complicates comparison, since results obtained on different materials, geometries and test protocols cannot be directly juxtaposed. The Perspective therefore calls for standardized benchmarks and testing workflows as a central requirement for comparing biosensing performance across materials, devices and laboratories, a step the authors regard as essential for the field’s credibility and maturation.

Biocompatibility and scalability round out the remaining challenges. Graphene and several other two-dimensional materials have shown encouraging compatibility with neurons and other cells, with purified neurons surviving on peptide-free graphene layers and graphene-based interfaces leaving target nerve cells unaltered, but toxicity depends strongly on material type, surface reactivity, dose and impurities, and other families such as graphene oxide or certain MXenes require careful assessment. Meanwhile, translating atomically thin sensors from individual hand-built devices to manufacturable technology demands wafer-scale growth, clean transfer processes and quality control, areas where machine learning is increasingly being deployed to optimize fabrication, screen candidate materials and even interpret complex chemical sensor arrays. Technology readiness levels differ widely across applications, with wearable and environmental sensing nearer to market and implantable diagnostics further behind.

If those obstacles can be cleared, the destination is compelling: flexible, portable point-of-care devices and conformal wearables that support continuous health monitoring and feed the Internet of Medical Things, an interconnected ecosystem of bioelectronic devices that collect, transmit and intelligently analyze health data at population scale. The authors frame the moment as a critical inflection point. The sensitivity problem has largely been solved; the selectivity, stability and reproducibility problems are now the frontier. By matching the unique properties of specific two-dimensional materials to specific sensing functions, and by grounding device design in material physics rather than empirical trial and error, the field aims to convert two decades of laboratory brilliance into reliable translational sensing technologies that patients and consumers can actually depend on.

Some of the physical underpinnings of these sensors deserve closer attention. In an electrolyte-gated configuration, the physiological liquid itself acts as the gate, so the electric double layer that forms at the material surface can capacitively modulate the channel with exceptional efficiency. This liquid gating, combined with the sizable quantum capacitance of graphene, means that even minute surface charge changes from adsorbed proteins or nucleic acids produce measurable shifts in device characteristics. At the same time, the ultimate detection floor is set by noise: low-frequency 1/f noise and charge fluctuations from trapped impurities and adsorbed water often dominate the signal, which is why operating points, electrolyte composition and surface cleanliness matter as much as the receptor chemistry itself.

The mechanical and chemical robustness of atomically thin films also underpins their wearable ambitions. Monolayer graphene can endure extreme bending and repeated tension-compression cycles without fracture, remains nearly transparent to visible light, and even acts as a corrosion-inhibiting coating on underlying metals. These attributes allow conformal patches to follow skin topology during motion while maintaining stable electrical contact, a prerequisite for long-term bioimpedance and electrophysiological recordings. Graphene multielectrode arrays have likewise served as versatile tools for extracellular measurements, and graphene oxide electrodes have been shown to elicit distinct calcium signaling in brain astrocytes, illustrating how material form and surface chemistry shape biological response.

Finally, the sheer breadth of the two-dimensional catalogue, documented in comprehensive material atlases, suggests that many sensing niches remain unclaimed. Systematic pairing of bandgap, phase, defect density and surface termination with a given analyte and operating environment offers a rational path forward, provided that cross-laboratory benchmarking becomes routine practice.

Subject of Research: Two-dimensional electronic biosensors based on graphene and related atomically thin materials

Article Title: Engineering two-dimensional electronic biosensors

Article References: Hasan, M. M., Bao, H., Montes-García, V., Zhang, Y., Ping, J., Samorì, P., Duan, X., & Kireev, D. (2026). Engineering two-dimensional electronic biosensors. Nature Reviews Electrical Engineering. https://doi.org/10.1038/s44287-026-00326-2

Image Credits: AI Generated

DOI: 10.1038/s44287-026-00326-2

Keywords: two-dimensional materials, graphene, biosensors, field-effect transistors, transition metal dichalcogenides, biofunctionalization, wearable biosensors, point-of-care diagnostics, Internet of Medical Things, sensor selectivity, sensor drift, MXenes

A new hydrogel design from Drexel University and Penn State University tackles that bottleneck by rethinking the soft interface layer that makes sensors “skin-tight.” Reported in Science Advances, the approach targets both adhesion and durability, aiming for a material that conforms instantly, remains conductive under motion, and can be reapplied without losing performance.

The key is how the hydrogel is manufactured. The researchers used a pH-driven chemical mechanism that delays gelation inside a syringe. By tuning pH, the formulation can be dispensed smoothly, then set on the body, rapidly forming a shape that matches the contours of the skin without tools or awkward fitting.

To improve electrical function and comfort, the team embedded laser-induced graphene and reduced graphene oxide flakes inside the gel. Rather than forming a dense, signal-blocking filler, these flakes create a porous internal network. That structure helps sweat permeate the hydrogel, reducing buildup that can interfere with electrode–skin coupling.

Adhesion is handled with polydopamine, often described as a “bio glue” because it mimics adhesive proteins found in biological tissues. In practice, this ingredient helps the sensor bond strongly through hair and sweat, maintaining contact during the mechanical stresses of everyday movement.

In preliminary tests, the hydrogel behaved like soft tissue and tolerated extreme stretching—up to about eighty times its original size. It also showed strong peel-and-reapply durability, maintaining function after dozens of cycles, and it bonded to a range of materials, suggesting versatility beyond skin-only applications.

Demonstrations included hydrogel electrocardiogram sensing on the wrist and chest, where stable signals persisted through bending and stretching. The same platform supported electro-oculography, tracking eye blinks during controlled blinking and eye-movement sessions.

Finally, the researchers used a multi-sensor array to capture anxiety-related physiological changes. By monitoring blinking, sweat, and heart activity while subjects were exposed to relaxing versus irritating stimuli, the sensors tracked coordinated electrical and sweat-related signatures as stress increased.

Overall, the work is positioned as a proof-of-concept for more reliable wearable bioelectronics. If optimized for specific use cases, the pH-tunable, reusable hydrogel interface could make conventional electrode measurements more robust in messy, real-life conditions.

Keywords

• Biosensors
• Hydrogels
• Graphene
• Wearable bioelectronics
• Adhesive materials
• Electrocardiography
• Electro-oculography
  Subject of Research: Biosensors and wearable bioelectronics using an adhesive, pH-tunable, graphene-reinforced hydrogel interface.
  Article Title: Ultrasoft, adhesive, pH-tunable hydrogel based on in situ functionalized laser-induced graphene for through-hair concurrent biosensing
  News Publication Date: 15-Jul-2026
  Web References: https://www.science.org/doi/10.1126/sciadv.aee5890
  References: 10.1126/sciadv.aee5890
  Image Credits: Drexel University

At the heart of this pioneering technology is the microfluidic patch, a flexible and lightweight device that adheres seamlessly to the skin, much like a temporary tattoo or a health monitoring bandage. Unlike conventional sweat sensors that often suffer from uneven sample collection and inconsistent analyte distribution, this microfluidic system employs tentacle-inspired microchannels that mimic the natural fluid-handling capabilities of cnidarian appendages. By harnessing bioinspired engineering principles, the patch ensures an efficient and uniform flow of sweat across multiple sensing sites, significantly improving the accuracy and reliability of sweat analysis.

The inspiration behind this technology stems from the unique morphology and biomechanics of cnidarian tentacles—those slender, flexible, and highly adaptive structures found in marine organisms like jellyfish and sea anemones. These natural tentacles exhibit an extraordinary ability to capture, channel, and distribute fluids and particulate matter through their sophisticated surface patterns and soft, compliant tissues. Replicating these design principles on a micro-scale, the researchers have developed microfluidic pathways that not only guide sweat through multiple sensor reservoirs but also maintain fluid integrity, preventing cross-contamination and loss of sample.

This innovative design addresses one of the longstanding challenges in wearable sweat sensors—achieving multiplexed sensing, where several analytes are detected simultaneously from the same sweat sample. Multiplexing is critical because sweat contains a complex mixture of metabolites, electrolytes, and biomarkers that collectively provide a comprehensive picture of an individual’s physiological state. However, existing sensors often face issues related to sample dilution and uneven analyte distribution, which compromise the accuracy of multiplex readings. By integrating a tentacle-inspired microfluidic network, Inukonda and Panda’s patch provides spatially resolved analyte distribution, enabling precise and simultaneous detection of multiple biomarkers with enhanced sensitivity.

Moreover, the flexible nature of the microfluidic patch allows it to conform closely to the dynamic surfaces of human skin, accommodating the natural movements and varying sweat secretion rates encountered during daily activities and exercise. This adhesion and compliance are critical for continuous, real-time monitoring of sweat composition, a feature that makes this technology particularly attractive for sports medicine, stress monitoring, and chronic disease management. The patch can provide dynamic physiological insights without the discomfort or inconvenience associated with traditional sampling methods.

In—addition to its superior biofluid handling—the patch utilizes cutting-edge sensor modules embedded within the microchannels that can selectively identify critical biomolecules such as glucose, lactate, sodium, and potassium. These sensors are fabricated using flexible electronics that maintain performance integrity despite the mechanical stresses imposed by skin deformation. The integration of multiplex sensing units within the biomimetic microfluidic architecture significantly increases the throughput of sweat analysis while reducing the need for bulky external instrumentation.

The research team employed advanced soft lithography and microfabrication techniques to construct the microfluidic networks, ensuring precise channel dimensions and surface chemistry that replicate the hydrophilic and hydrophobic zones observed in natural tentacles. Such meticulous engineering is essential to optimize sweat capillary action and fluid dynamics within the patch, enabling passive sweat wicking without external pumps or power sources. This energy-efficient design not only prolongs device longevity but also enhances user convenience.

Comprehensive in vitro and on-body tests demonstrated the patch’s exceptional performance in sweat collection and analyte detection under varied physiological conditions. Trials involving human volunteers engaged in physical exercise scenarios confirmed the patch’s ability to maintain consistent fluid flow and analyte separation, even under the challenges of sweat rate variability and movement-induced artifacts. The data acquired from these experiments confirmed strong correlation with standard biochemical assays, validating the device’s analytical accuracy.

Importantly, the device exhibits potential applicability beyond health monitoring, extending to domains like military personnel surveillance, space missions, and occupational health where real-time physiological data is crucial. The patch’s small form factor and robustness make it ideally suited for continuous deployment in harsh or constrained environments, where traditional monitoring tools may falter. By offering multiplex sweat sensing with robust analyte distribution, this cnidarian-inspired innovation opens new frontiers in wearable biosensing technologies.

From a commercial perspective, the simplicity of the patch’s design and its compatibility with existing manufacturing processes lay a solid foundation for rapid scale-up and mass production. The researchers envisage an ecosystem where such patches become a part of everyday health routines, transmitting data seamlessly to smartphones or cloud-based platforms for advanced analytics and personalized feedback. This vision aligns strongly with the global push toward digital health paradigms and closed-loop healthcare systems driven by real-time biometric data.

Looking forward, efforts are underway to further refine the patch by incorporating wireless communication modules and energy harvesting elements, potentially enabling a fully autonomous sweat sensing solution. There is also ongoing work into expanding the library of detectable biomarkers to include hormones and proteins linked to immune and metabolic health. Such advancements will broaden the scope of wearable sweat sensors, enabling complex physiological monitoring that rivals blood-based diagnostics in accuracy and convenience.

The implications of this research extend into broader scientific and engineering communities by showcasing how biological form and function can serve as blueprints for high-performance technological devices. The microfluidic patch exemplifies this biomimetic approach, demonstrating how emulating nature’s fluid dynamics can overcome technical barriers in human health monitoring. It underlines the importance of interdisciplinary collaboration, merging insights from biology, materials science, and electronics to yield innovative solutions responsive to real-world needs.

In summary, the cnidarian tentacle-inspired microfluidic patch developed by Inukonda and Panda represents a quantum leap in the design of wearable sweat sensors. By providing improved analyte distribution and multiplex detection capabilities in a comfortable, flexible format, this technology is poised to redefine personalized health monitoring and accelerate the adoption of non-invasive biosensing platforms. Its success heralds a new chapter in the synergy between nature-inspired engineering and digital healthcare, opening pathways to smarter, more accessible diagnostics for all.

As we stand on the cusp of a biomonitoring revolution, innovations such as this underscore the profound potential locked within bioinspiration. The humble tentacles of marine creatures, adapted over millions of years to manage fluid environments flawlessly, now illuminate the pathway toward smarter, more accurate, and user-friendly wearable technology. This convergence of biology and engineering heralds a future where continuous health insights are effortlessly integrated into everyday life, empowering individuals to take proactive control of their wellness like never before.

Subject of Research: Wearable biosensors, biomimetic microfluidic devices for multiplex sweat sensing

Article Title: Cnidarian tentacle-inspired microfluidic patch for improved analyte distribution in multiplex sweat sensing

Article References:
Inukonda, S.M., Panda, S. Cnidarian tentacle-inspired microfluidic patch for improved analyte distribution in multiplex sweat sensing. npj Flex Electron 9, 100 (2025). https://doi.org/10.1038/s41528-025-00439-y

Image Credits: AI Generated