The hybrid device, screen-printed on two sides of the fabric, is designed to scavenge biochemical energy from the wearer's sweat using a biofuel cell module, and to store the harvested bioenergy into the supercapacitor module for subsequent use.

Diabetic ketoacidosis (DKA), a severe complication of diabetes mellitus with potentially fatal consequences, is characterized by hyperglycemia and metabolic acidosis due to the accumulation of ketone bodies, which requires people with diabetes to monitor both glucose and ketone bodies. However, despite major advances in diabetes management mainly since the emergence of new-generation continuous glucose monitoring (CGM) devices capable of in vivo monitoring of glucose directly in the interstitial fluid (ISF), the continuous monitoring of ketone bodies is yet to be addressed. Here, we present the first use of a real-time continuous ketone bodies monitoring (CKM) microneedle platform. The system is based on the electrochemical monitoring of β-hydroxybutyrate (HB) as the dominant biomarker of ketone formation. Such real-time HB detection has been realized using the β-hydroxybutyrate dehydrogenase (HBD) enzymatic reaction and by addressing the major challenges associated with the stable confinement of the enzyme/cofactor couple (HBD/NAD + ) and with a stable and selective lowpotential fouling-free anodic detection of NADH. The resulting CKM microneedle device displays an attractive analytical performance, with high sensitivity (with low detection limit, 50 μM), high selectivity in the presence of potential interferences, along with good stability during prolonged operation in artificial ISF. The potential applicability of this microneedle sensor toward minimally invasive monitoring of ketone bodies has been demonstrated in a phantom gel skin-mimicking model. The ability to detect HB along with glucose and lactate on a single microneedle array has been demonstrated. These findings pave the way for CKM and for the simultaneous microneedle-based monitoring of multiple diabetes-related biomarkers toward a tight glycemic control.

Despite the fast development of various energy harvesting and storage devices, their judicious integration into efficient, autonomous, and sustainable wearable systems has not been widely explored. Here, we introduce the concept and design principles of e-textile microgrids by demonstrating a multi-module bioenergy microgrid system. Unlike earlier hybrid wearable systems, the presented e-textile microgrid relies solely on human activity to work synergistically, harvesting biochemical and biomechanical energy using sweat-based biofuel cells and triboelectric generators, and regulating the harvested energy via supercapacitors for high-power output. Through energy budgeting, the e-textile system can efficiently power liquid crystal displays continuously or a sweat sensor-electrochromic display system in pulsed sessions, with half the booting time and triple the runtime in a 10-min exercise session. Implementing “compatible form factors, commensurate performance, and complementary functionality” design principles, the flexible, textile-based bioenergy microgrid offers attractive prospects for the design and operation of efficient, sustainable, and autonomous wearable systems.

While the current smartwatches and cellphones can readily track mobility and vital signs, a new generation of wearable devices is rapidly developing to enable users to monitor their health parameters at the molecular level. Within this emerging class of wearables, microneedle‐based transdermal sensors are in a prime position to play a key role in synergizing the significant advantages of dermal interstitial fluid (ISF) as a rich source of clinical indicators and painless skin pricking to allow the collection of real‐time diagnostic information. While initial efforts of microneedle sensing focused on ISF extraction coupled with either on‐chip analysis or off‐chip instrumentation, the latest trend has been oriented toward assembling electrochemical biosensors on the tip of microneedles to allow direct continuous chemical measurements. In this context, significant advances have recently been made in exploiting microneedle‐based devices for real‐time monitoring of various metabolites, electrolytes, and therapeutics and toward the simultaneous multiplexed detection of key chemical markers; yet, there are several grand challenges that still exist. In this review, we outline current progress, recent trends, and new capabilities of microneedle‐empowered sensors, along with the current unmet challenges and a future roadmap toward transforming the latest innovations in the field to commercial products.

There are urgent needs for sensing devices capable of distinguishing between episodes of opioid overdose and nerve agent poisoning. This work presents a wearable microneedle sensor array for minimally invasive continuous electrochemical detection of opioid (OPi) and organophosphate (OP) nerve agents on a single patch platform. The new multimodal microneedle sensor array relies on unmodified and organophosphorus hydrolase (OPH) enzyme-modified carbon paste (CP) microneedle electrodes for square wave voltammetric (SWV) detection of the fentanyl and nerve agent targets, respectively. Such real-time simultaneous sensing provides distinct unique information, along with attractive analytical performance, including high sensitivity, selectivity, and stability, for real-time on-body OPi–OP analysis. The patch represents the first sensing device capable of continuously monitoring fentanyl down to the nanomolar level through a nanomaterial-based multilayered surface architecture. Applicability of the sensor array toward opioids screening is demonstrated for morphine and norfentanyl. Successful OPi–OP detection conducted in a skin-mimicking phantom gel demonstrates the suitability of the device for rapid on-body sensing. Such progress toward continuous minimally invasive transdermal analysis of drugs of abuse and nerve agents holds promise for rapid countermeasures for protecting soldiers, civilians, and healthcare personnel.

A novel and highly sensitive disposable glucose sensor strip was developed using direct laser engraved graphene (DLEG) decorated with pulse deposited copper nanocubes (CuNCs). The high reproducibility (96.8%), stability (97.4%) and low cost demonstrated by this 3-step fabrication method indicates that it could be used for high volume manufacturing of disposable glucose strips. The fabrication method also allows for a high degree of flexibility, allowing for control of the electrode size, design, and functionalization method. Additionally, the excellent selectivity and sensitivity (4,532.2 μA/mM.cm2), low detection limit (250 nM), and suitable linear range of 25 μM–4 mM, suggests that these sensors may be a great potential platform for glucose detection within the physiological range for tear, saliva, and/or sweat.

Rapid and precise analytical tools are essential for monitoring food safety and screening of any undesirable contaminants, allergens, or pathogens, which may cause significant health risks upon consumption. Substantial developments in analytical techniques have empowered the analyses and quantitation of these contaminants. However, conventional techniques are limited by delayed analysis times, expensive and laborious sample preparation, and the necessity for highly-trained workers. Therefore, prompt advances in electrochemical biosensors have supported significant gains in quantitative detection and screening of food contaminants and showed incredible potential as a means of defying such limitations. Apart from indicating high specificity towards the target analytes, these biosensors have also addressed the challenge of food industry by providing high analytical accuracy within complex food matrices. Here, we discuss some of the recent advances in this area and analyze the role and contributions made by electrochemical biosensors in the food industry. This article also reviews the key challenges we believe biosensors need to overcome to become the industry standard.

Graphene‐based composites have received attention as part of the drive towards next‐generation electronic and energy‐storage technologies. However, current graphene synthesis methods are limited by complex, time‐consuming, toxic, costly, and/or often low‐yield procedures. The synthesis of a novel stretchable graphene‐polyurethane‐poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate ink aimed at printing wearable electronics is reported. The procedure is based on low‐cost high‐yield production of high‐performance graphene ink produced by laser induction of polyimide film followed by harvesting the graphene. Screen printing is used to fabricate flexible and intrinsically stretchable micro‐supercapacitors (S‐MSCs) printed on different substrates. The resulting graphene‐based printed S‐MSCs display a remarkably high capacitive performance and attractive mechanical resiliency. High specific areal capacitance, above 23 mF cm−2, is achieved, which is the highest areal capacitance reported for highly stretchable, printed graphene supercapacitors. A repeated (200 cycles) stretchability beyond 100% is obtained while maintaining more than 85% of the S‐MSCs' original capacitance. This unique and highly scalable graphene ink synthesis method holds considerable promise for application in low‐cost graphene‐based chemical formulation, especially in the field of printed and wearable electronics toward multifunctional, energy‐storage systems capable of withstanding severe mechanical deformation while maintaining their optimal electrochemical performance.