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Periprosthetic infection is one of the most devastating complications following orthopaedic surgery. Rapid detection of an infection can change the treatment pathway and improve outcomes for the patient. In here, we propose a miniaturized lactate biosensor developed on a flexible substrate and integrated on a small-form bone implant to detect infection. The methods for lactate biosensor fabrication and integration on a bone implant are fully described within this study. The system performance was comprehensively electrochemically characterised, including with L-lactate solutions prepared in phosphate-buffered saline and culture medium, and interferents such as acetaminophen and ascorbic acid. A proof-of-concept demonstration was then conducted with ex vivo ovine femoral heads incubated with and without exposure to Staphylococcus epidermidis. The sensitivity, current density and limit-of-detection levels achieved by the biosensor were 1.25 µA mM-1, 1.51 µA.M-1.mm-2 and 66 µM, respectively. The system was insensitive to acetaminophen, while sensitivity to ascorbic acid was half that of the sensitivity to L-lactate. In the ex vivo bone model, S. epidermidis infection was detected within 5 h of implantation, while the control sample led to no change in the sensor readings. This pioneering work demonstrates a pathway to improving orthopaedic outcomes by enabling early infection diagnosis.

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A novel approach for simultaneous detection of iron and potassium via a smartphone-based potentiometric method is proposed in this study. The screen printed electrodes were modified with carbon black nanomaterial and ion selective membrane including zinc (II) phtalocyanine as the ionophore. The developed Fe3+-selective electrode and K+-selective electrode exhibited detection limits of 1.0 × 10-6 M and 1.0 × 10-5 M for Fe3+ and K+ ions, respectively. The electrodes were used to simultaneously detect Fe3+ and K+ ions in apple juice, skim milk, soybean and coconut water samples with recovery values between 90%-100.5%, and validated against inductively coupled plasma-optical emission spectrometry. Due to the advantageous characteristics of the sensors and the portability of Near Field Communication potentiometer supported with a smartphone application, the proposed method offers sensitive and selective detection of iron and potassium ions in food and beverage samples at the point of need.

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Point-of-care testing (POCT) devices play a crucial role as tools for disease diagnostics, and the integration of biorecognition elements with electronic components into these devices widens their functionalities and facilitates the development of complex quantitative assays. Unfortunately, biosensors that exploit large conventional IgG antibodies to capture relevant biomarkers are often limited in terms of sensitivity, selectivity, and storage stability, considerably restricting the use of POCT in real-world applications. Therefore, we used nanobodies as they are more suitable for fabricating electrochemical biosensors with near-field communication (NFC) technology. Moreover, a flow-through microfluidic device was implemented in this system for the detection of C-reactive protein (CRP), an inflammation biomarker, and a model analyte. The resulting sensors not only have high sensitivity and portability but also retain automated sequential flow properties through capillary transport without the need for an external pump. We also compared the accuracy of CRP quantitative analyses between commercial PalmSens4 and NFC-based potentiostats. Furthermore, the sensor reliability was evaluated using three biological samples (artificial serum, plasma, and whole blood without any pretreatment). This platform will streamline the development of POCT devices by combining operational simplicity, low cost, fast analysis, and portability.

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In this work, flower-like ZnO nanoparticles (ZnONPs) were synthesized using zinc nitrate (Zn(NO3)2 6H2O) as a precursor with KOH. The morphology of the ZnONPs was controlled by varying the synthesis temperature at 50, 75 and 95 °C. The morphology and structure of ZnONPs were characterized using Scanning Electron Microscopy, and X-Ray Diffraction and Brunauer-Emmett Teller analysis. ZnONPs were successfully synthesized by a simple chemical precipitation method. A synthesis temperature of 75 °C produced the most suitable flower-like ZnONPs, which were combined with graphene nanoplatelets to develop a label-free electrochemical immunosensor for the detection of the colon cancer biomarker carcinoembryonic antigen in human serum. Under optimum conditions, the developed immunosensor showed a linear range of 0.5-10.0 ng mL-1 with a limit of detection of 0.44 ng mL-1. The label-free electrochemical immunosensor exhibited good selectivity, reproducibility, and repeatability, and recoveries were excellent. The immunosensor is used with a Near-Field Communication potentiostat connected to a smartphone to facilitate point-of-care cancer detection in low-resource locations.

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A portable device offering effortlessness, mobility, and affordability for real-time and on-site monitoring of heavy metals is currently in great demand to maintain environmental sustainability. Herein, a platform utilizing a biopolymeric gel-based electrolyte for the on-field simultaneous determination of Cd(II) and Pb(II) is described. Pectin, a natural polymer, was exploited as a chemical delivery medium on account of its biodegradability, environmental friendliness, and rapid dissolving characteristics. The gel electrolyte was prepared by having pectin dissolved in KCl mixed with Sb(III)-Bi(III) bimetallic alloy solution, and casted onto a paper substrate. An in situ bimetallic alloy and pre-mixed bismuth nanoparticles modified screen-printed graphene electrode (Sb-Bi/BiNP/SPGE) were employed to enhance the electrochemical signals of Cd(II) and Pb(II) for the differential pulse anodic stripping voltammetry (DPASV). It was demonstrated that the platform was capable of generating sharp and well-defined current signals, achieving the low detection limits of 50.98 ng mL-1 for Cd(II) and 40.80 ng mL-1 for Pb(II). The reproducibility, as indicated by the relative standard deviation, was found to be less than 10.4 % (n = 10) for the developed gel-based device when coupled with a wireless near field communication (NFC) potentiostat. Lastly, the obtained sensor was applied for quantification of Cd and Pb in potentially contaminated groundwater samples. The recoveries obtained were satisfactorily within the acceptable range. The newly designed platform exhibited several advantages, including small sample volume (µL), low-cost, no sample preparation requirements, and being environmentally friendly. The convenience of a portable device utilizing the proposed biopolymeric gel-based electrolyte for on-field analysis makes it highly appealing for various applications.

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Rapid detection of pathogens at the point-of-need is crucial for preventing the spread of human, animal and plant diseases which can have devastating consequences both on the lives and livelihood of billions of people. Colorimetric, lateral flow assays consisting of a nitrocellulose membrane, are the preferred format today for low-cost on-site detection of pathogens. This assay format has, however, historically suffered from poor analytical performance and is not compatible with digital technologies. In this work, we report the development of a new class of digital diagnostics platform for precision point-of-need testing. This new versatile platform consists of two important innovations: i) A wireless and batteryless, microcontroller-based, low-cost Near Field Communication (NFC)-enabled potentiostat that brings high performance electroanalytical techniques (cyclic voltammetry, chronoamperometry, square wave voltammetry) to the field. The NFC-potentiostat can be operated with a mobile app by minimally trained users; ii) A new approach for producing nitrocellulose membranes with integrated electrodes that facilitate high performance electrochemical detection at the point-of-need. We produced an integrated system housed in a 3D-printed phone case and demonstrated its use for the detection of Maize Mosaic Virus (MMV), a plant pathogen, as a proof-of-concept application.

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Wireless sensor tags in flexible formats have numerous applications; some are commercially available for specific target applications. However, most of these wireless sensor tags have been used for single-sensing applications. In this study, we designed a printed circuit board (PCB) module (13 mm × 13 mm) for near-field communication-enabled sensor tags with both electrical resistance and capacitance read-out channels that enables dual-channel sensing. As part of the wireless sensor tag, a square antenna pattern was printed directly on a flexible poly(ethylene terephthalate) (PET) substrate and integrated into the PCB module to demonstrate a dual-channel temperature and ethylene gas sensor. The temperature and ethylene sensors were printed using a positive temperature coefficient ink and a tin oxide (SnO2) nanoparticle ink, respectively. With dual sensing capabilities, this type of sensor tag can be used in smart packaging for the quality monitoring of fresh produce (e.g., bananas) by tracking temperature and ethylene concentration in the storage/transport environment.

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This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have aroused great interest in new batteryless NFC sensors. The fact that coil antennas are not importantly affected by the body compared with other wireless sensors based on far-field communications makes this technology suitable for future wearable point-of-care testing (PoCT) devices. This review first compares energy harvesting based on NFC to other energy-harvesting technologies. Next, some practical recommendations for designing and tuning NFC-based tags are described. Power transfer is key because in most cases, the energy harvested has to be stable for several seconds and not contaminated by undesired signals. For this reason, the effect of the dimensions of the coils and the conductivity on the wireless power transfer is thoroughly discussed. In the last part of the review, the state of the art in NFC-based chemical and biosensors is presented. NFC-based tags (or sensor tags) are mainly based on commercial or custom NFC ICs, which are used to harvest the energy from the RF field generated by the smartphone to power the electronics. Low-consumption colorimeters and potentiostats can be integrated into these NFC tags, opening the door to the integration of chemical sensors and biosensors, which can be harvested and read from a smartphone. The smartphone is also used to upload the acquired information to the cloud to facilitate the internet of medical things (IoMT) paradigm. Finally, several chipless sensors recently proposed in the literature as a low-cost alternative for chemical applications are discussed.

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Biofilm-associated infections, which are able to resist antibiotics, pose a significant challenge in clinical treatments. Such infections have been linked to various medical conditions, including chronic wounds and implant-associated infections, making them a major public-health concern. Early-detection of biofilm formation offers significant advantages in mitigating adverse effects caused by biofilms. In this work, we aim to explore the feasibility of employing a novel wireless sensor for tracking both early-stage and matured-biofilms formed by the medically relevant bacteria Staphylococcus aureus and Pseudomonas aeruginosa. The sensor utilizes electrochemical reduction of an AgCl layer bridging two silver legs made by inkjet-printing, forming a part of near-field-communication tag antenna. The antenna is interfaced with a carbon cloth designed to promote the growth of microorganisms, thereby serving as an electron source for reduction of the resistive AgCl into a highly-conductive Ag bridge. The AgCl-Ag transformation significantly alters the impedance of the antenna, facilitating wireless identification of an endpoint caused by microbial growth. To the best of our knowledge, this study for the first time presents the evidence showcasing that electrons released through the actions of bacteria can be harnessed to convert AgCl to Ag, thus enabling the wireless, battery-less, and chip-less early-detection of biofilm formation.

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In the model-driven security domain, access control systems provide an application for handling access of persons through controlled gates. A gate, such as a door, can have a lock mechanism for securing the area from unauthorized access. Most commercial solutions for access control management offer pre-packaged software systems where customization of the authorization logic is either not allowed or subject to payment. Moreover, cross-platform development is a barrier for solution providers due to the high cost of development and maintenance that it implies. To overcome these limitations and further optimize the entire access control systems development process, we propose a model-driven approach that supports automatic code generation to enable communication between an IoT infrastructure and platforms for Facility Access Management. Specifically, the approach combines the benefits of Near-Field Communication (NFC) and Tinkerforge (i.e., an open-source hardware platform) with model-driven techniques. This allows the approach to exploit both behavioral and structural models for the modeling and the consequent code generation of part of the authorization mechanism, thus providing complete coverage of the code generated for the whole system. We implemented and evaluated our approach in a real-world case study within the premises of a fitness center with an IoT infrastructure consisting of several heterogeneous sensors by showing its practical applicability. Experimental results demonstrate the effectiveness of our approach in supporting abstraction and automation concerning traditional code-centric development through code generation features. Consequently, our approach makes the whole development process less time-consuming and error-prone, thus reducing the system's time to market.

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We developed a fully integrated smart sensing device for on-site testing of food to detect trace formaldehyde (FA). A nano-palladium grafted laser-induced graphene (nanoPd@LIG) composite was synthesized by one-step laser irradiation of a Pd2+-chitosan-polyimide precursor. The composite was synthesized in the form of a three-electrode sensor on a polymer substrate. The electrochemical properties and morphology of the fabricated composite were characterized and the electrochemical kinetics of FA oxidation at the nanoPd@LIG electrode were investigated. The nanoPd@LIG electrode was combined with a smart electrochemical sensing (SES) device to determine FA electrochemically. The proposed SES device uses near field communication (NFC) to receive power and transfer data between a smartphone interface and a battery-free sensor. The proposed FA sensor exhibited a linear detection range from 0.01 to 4.0 mM, a limit of detection of 6.4 µM, good reproducibility (RSDs between 2.0 and 10.1%) and good anti-interference properties for FA detection. The proposed system was used to detect FA in real food samples and the results correlated well with the results from a commercial potentiostat and a spectrophotometric analysis.

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World population and life expectancy have increased steadily in recent years, raising issues regarding access to medical treatments and related expenses. Through last-generation medical sensors, NFC (Near Field Communication) and radio frequency identification (RFID) technologies can enable healthcare internet of things (H-IoT) systems to improve the quality of care while reducing costs. Moreover, the adoption of point-of-care (PoC) testing, performed whenever care is needed to return prompt feedback to the patient, can generate great synergy with NFC/RFID H-IoT systems. However, medical data are extremely sensitive and require careful management and storage to protect patients from malicious actors, so secure system architectures must be conceived for real scenarios. Existing studies do not analyze the security of raw data from the radiofrequency link to cloud-based sharing. Therefore, two novel cloud-based system architectures for data collected from NFC/RFID medical sensors are proposed in this paper. Privacy during data collection is ensured using a set of classical countermeasures selected based on the scientific literature. Then, data can be shared with the medical team using one of two architectures: in the first one, the medical system manages all data accesses, whereas in the second one, the patient defines the access policies. Comprehensive analysis of the H-IoT system can be useful for fostering research on the security of wearable wireless sensors. Moreover, the proposed architectures can be implemented for deploying and testing NFC/RFID-based healthcare applications, such as, for instance, domestic PoCs.

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This work studies the feasibility of using a battery-less Near-Field Communication (NFC) potentiostat for the next generation of electrochemical point-of-care sensors. A design based on an NFC microchip, a microcontroller, and a custom potentiostat based on an operational amplifier is presented. A proof-of-concept prototype has been designed and used to quantify glucose concentration using commercial glucose test strips from chronoamperometry measurements. The device is harvested and the sensor is read using a mobile phone. The prototype uses an antenna loop covered with ferrite sheets to ensure stable operation of the electronics when the mobile phone is used as reader. The use of ferrite reduces the detuning caused by the proximity of the metal parts of the mobile phone. A comparison with a commercial glucometer device is provided. Results obtained using a commercial glucometer and those provided by the proposed potentiostat show an excellent agreement.

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Chronic studies in the fasting and fed states of conscious subjects are fundamental for understanding the pathophysiological significance of functional gastrointestinal (GI) disorders and motility dysfunctions. To study the electrophysiology of the GI tract in the long term, the development of gastric implants is essential. This paper presents the development of an implantable system capable of monitoring the bioelectrical activity of the gastric system and modulating the activity in freely behaving rodents. The system consists of a miniature-sized implantable unit (IU), a stationary unit (SU) that communicates with the IU over a 2.4 GHz far-field radio frequency (RF) bidirectional link, and a charging unit (CU) that establishes an inductive 13.56 MHz near-field communication (NFC) with the IU, implementing an adaptive wireless power transfer (WPT). The CU can generate an adjustable power between +20 dBm and +30 dBm, and, in the presence of body movements and stomach motility, can deliver a constant rectified voltage to the IU. The live subject's exposure to the electromagnetic WPT in the developed system complies with the RF energy absorption restrictions for health and safety concerns. The system can be utilized to investigate the relationship between functional GI disorders and dysrhythmias in the gastric bioelectrical activity and study the potential of electroceutical therapies for motility dysfunctions in clinical settings.

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BACKGROUND: The prevalence of peritoneal dialysis (PD) in Thailand is increasing rapidly in part because of Thailand's Peritoneal Dialysis First policy. PD is a home-based renal replacement therapy in which patients with chronic kidney disease perform up to 4 exchanges of dialysate fluid per day in the peritoneal cavity. Overhydration is one of the most common complications in patients on PD and is associated with increased morbidity and mortality. To monitor hydration status, patients collect hydration metrics, including body weight, blood pressure, urine output, and ultrafiltration volume, from each dialysis cycle and enter this information into a PD logbook. This information is reviewed bimonthly at PD clinic appointments. The chronic kidney disease-PD (CKD-PD) app with near-field communication (NFC) and optical character recognition (OCR) was developed to automate hydration metric collection. The information was displayed in the app for self-monitoring and uploaded to a database for real-time monitoring by the PD clinic staff. Early detection and treatment of overhydration could potentially reduce the morbidity and mortality related to overhydration. OBJECTIVE: This study aims to identify usability issues and technology adoption barriers for the CKD-PD app with NFC and OCR and a monitoring system and to use this information to make rapid cycle improvements. METHODS: A multidisciplinary team of nephrologists, PD clinic nurses, computer programmers, and engineers trained and observed 2 groups of 5 participants in the use of the CKD-PD app with NFC and OCR and a monitoring system. The participants were observed using technology in their homes in 3 phases. The data collected included the Unified Theory of Acceptance and Use of Technology questionnaire, think-aloud observation, user ratings, completion of hydration metrics, and upload of hydration metrics to the central database. These results were used by the team between phases to improve the functionality and usefulness of the app. RESULTS: The CKD-PD app with NFC and OCR and a monitoring system underwent 3 rapid improvement cycles. Issues were identified regarding the usability of the NFC and OCR data collection, app stability, user interface, hydration metric calculation, and display. NFC and OCR improved hydration metric capture; however, issues remained with their usability. App stability and user interface issues were corrected, and hydration metrics were successfully uploaded by the end of phase 3. Participants' scores on technology adoption decreased but were still high, and there was enthusiasm for the self-monitoring and clinical communication features. CONCLUSIONS: Our rapid cycle process improvement methodology identified and resolved key barriers and usability issues for the CKD-PD app with NFC and OCR and a monitoring system. We believe that this methodology can be accomplished with limited training in data collection, statistical analysis, and funding.

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Full-duplex (FD) enabled wireless power transfer (WPT) system via textile for miniaturized IMD is presented. By utilizing the battery-free near-field communication (NFC) method, the system realizes wireless power and data transmission without a bulky battery or energy harvester which can diminish the physical size of implantable medical device (IMD). Moreover, using textile as a medium of power transmission, the system overcomes the drawback and extends the limited effective range of the NFC method. In addition, as realizing simultaneous bidirectional data transmission over a single data channel, IMD has been further miniaturized. The proposed system including an external transmitter and the minimized IMD receiver supports 200 kbps and 50 kbps data rates for FSK downlink and LSK uplink telemetries at the same time with bit error rate (BER) of < 8 × 10 - 5 and < 4 × 10 - 5 , respectively. The measured power transfer efficiency (PTE) and DC-to-DC power delivered to load (PDL) are 5.77% and 64 mW at 0.5/60 cm of vertical/horizontal distance.

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Totally implanted access ports (TIAP) are widely used with oncology patients requiring long term central venous access for the delivery of chemotherapeutic agents, infusions, transfusions, blood sample collection and parenteral nutrition. Such devices offer a significant improvement to the quality of life for patients and reduced complication rates, particularly infection, in contrast to the classical central venous catheters. Nevertheless, infections do occur, with biofilm formation bringing difficulties to the treatment of infection-related complications that can ultimately lead to the explantation of the device. A smart TIAP device that is sensor-enabled to detect infection prior to extensive biofilm formation would reduce the cases for potential device explantation, whereas biomarkers detection within body fluids such as pH or lactate would provide vital information regarding metabolic processes occurring inside the body. In this paper, we propose a novel batteryless and wireless device suitable for the interrogation of such markers in an embodiment model of an TIAP, with miniature biochemical sensing needles. Device readings can be carried out by a smartphone equipped with Near Field Communication (NFC) interface at relative short distances off-body, while providing radiofrequency energy harvesting capability to the TIAP, useful for assessing patient's health and potential port infection on demand.

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Mobile phones have been used in combination with point of care (PoC) devices for over a decade now. However, their use seems restricted to the detection of sensing events using the video and camera functions. In contrast, the complementary ability to use mobile phones to power such PoC devices has been largely unexplored. This work demonstrates the proof-of-principle that a smartphone can be used to both power and analyze an electrochemiluminescence (ECL) detection system. A printed device is presented featuring an electrochemical cell connected in series to a rectenna that is able to use the Near Field Communication (NFC, 13.56 MHz) signal to provide the energy needed to generate ECL from Ru(bpy)32+/tri-n-propylamine. The emitted light, the intensity of which is directly proportional to the concentration of the ruthenium complex, can then be captured by the mobile phone camera and analyzed. This work presents the fabrication and the electrical and electrochemical characterization of the device. Effective voltages ranging from 0.90 to 4.50 V have been recorded, depending on the coupling between emitter and receiver, which translate into working electrode potentials ranging from 0.76 up to 1.79 V vs Ag. Detection and quantification limits of 0.64 and 1.52 µM, respectively, have been achieved for Ru(bpy)32+, and linear ranges up to 0.1 mM (red channel) and no less than 1.0 mM (green channel) have been found.

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The electrochemical determination of five heavy metals is demonstrated using a wireless and card-sized potentiostat coupled with a smartphone through near-field communication (NFC) technology. A smartphone application was customized to command the NFC potentiostat, collect real-time signals, process the data, and ultimately display the quantities of the selected elements. The screen-printed graphene electrode (SPGE) was simply fabricated and modified using different nanomaterials for each heavy metal. Using differential pulse voltammetry (DPV) mode on the smartphone, the signal peaks were presented at + 10 mV for As(III), + 350 mV for Cr(VI), 0 mV for Hg(II), - 900 mV for Cd(II), and - 680 mV vs. Ag/AgCl for Pb(II). The linear ranges were 25-500, 250-25,000, 100-1,500, 25-750, 25-750 ng mL-1 with detection limits of 3.0, 40, 16, 2.0, and 0.95 ng mL-1 for As(III), Cr(VI), Hg(II), Cd(II), and Pb(II), respectively. The reproducibility in terms of relative standard deviation was less than 8.8% (n = 5 devices) of the developed SPGE coupled with the NFC potentiostat. Various samples for different applications (e.g., food safety and environmental monitoring) were analyzed and quantified using the proposed sensors. The results from this sensor indicate that there is no significant difference (95% confidence level) compared with those obtained from the traditional ICP-OES method, while the recoveries were found in the acceptable range of 80-111%. Hence, it can be deduced that this recent advanced technology of the NFC potentiostat developed for heavy metal analysis offers a highly sensitive and selective detection, yet the sensor remains compact, low-cost, and readily accessible to end-users.

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The paper covers one of the communication technologies used in wireless sensor networks. We have presented improvements in existing radio frequency identification (RFID) systems to address the problem of the phase selection in active load modulation (ALM). The phase selection affects the interoperability of communication devices and has to be addressed in the design phase of a new tag. A novel transmission method is presented to make the phase selection irrelevant for device interoperability. A second solution is shown to improve the existing system synchronization, which allows operation with arbitrary selected phase. A mathematical analysis of signals present on the antenna was used together with the reference reader model to perform an analysis of proposed improvements. We proved that the proposed transmission method is less affected by phase selection. Furthermore, we demonstrated that existing system improvement allows synchronization and operation at an arbitrarily selected phase despite the continuous transmission and large signal-to-interference ratio.