Recent Advances in Paper-Based Sensors

Microfluidic paper-based sensors as a new type of microsample detection technology are widely used in medical diagnosis, environmental monitoring, and food safety testing. Inkjet printing has the advantages of simplicity, speed, flexibility, high resolution, low cost, and efficient mass production and has become one of the most cutting-edge technologies in the manufacture of paper-based sensors. In this work, a fully inkjet printing preparation method was proposed for paper-based sensors, which can achieve high-precision, multichannel, and visual fluorescence detection. Three kinds of fluorescent carbon dots (CDs; r-CDs, b-CDs, and y-CDs) were fabricated into inkjet ink by adding a suitable ratio of solvent, PEG, and surfactant FS3100 to control its viscosity, surface tension, and other influencing factors, obtaining the best-visualized fluorescence response on paper. To optimize the full inkjet printing process of the paper-based sensor, we studied the influence of factors such as the hydrophobic material AKD formula, postprocessing conditions, and the structure of the hydrophilic and hydrophobic channels on the paper-based detection accuracy, and it was found that proper AKD concentration, curing time, and temperature can make AKD fully react with paper-based surface groups and produce more hydrophobic groups on the surface and inside of the filter paper, which can form paper-based microfluidic sensors with clear boundaries and fast transmission speed at low cost and high efficiency. The fabricated sensor is used for the fluorometric determination of vitamin C (AA), NO2-, and sunset yellow (SY) at the same time, and the limits of visual detection by eyes are 6 mmol/L (NO2-), 60 μmol/L (SY), and 40 mmol/L (AA). The mechanism of inkjet printing is investigated in detail, which is simple, reliable, and easy to realize mass production and can realize highly sensitive, on-site, and visual detection for food additives.

In this work we present a system for distributed video surveillance based on the Client-Server model. The system we present can be accessed via portable devices. In many real-world scenarios is useful, or sometimes necessary, to have portable devices that can receive real-time data from a selected camera, to prevent or to manage anomalous activities. The system provides reliable, high speed, secure and real-time communication among all its components, which are the Repository, the Node and the Portable Device. Both Repository and Node can act as a server. The Repository can provide services to both Nodes and Portable Devices, while the Nodes provide services only to the Portable Device. The portable device can only act as a client, using the services offered by the other two parts. In our system, a portable device is assumed to know only the location of the Repository which permits to get the list of nodes connected with one or more camera(s). When a portable device gets the list, it can choose which node intends to connect to, to get the images of its connected camera(s). The security of the interaction among Node-Repository and Node-Portable Device is guaranteed by using the SSL/TLS protocol. The interaction among nodes and portable devices is secured by using an invisible digital watermarking algorithm on each image, before that image is sent from a node to a portable device. The latter extracts the watermark from the image and verifies the identity of the node.

Portable oxygen devices simplify and facilitate patient therapy. This study was designed to compare S(pO2) and patient satisfaction with a portable oxygen concentrator or a combined system consisting of a fixed device with continuous-flow oxygen dispensation and a portable device with pulse dispensation for ambulation. This crossover trial assessed 25 subjects with COPD (92% men, mean age of 72.2 ± 7.4 y, mean FEV1 of 34.14 ± 12.51% of predicted) at 4 hospitals in Madrid. All subjects had previously used the combined system, consisting of a fixed oxygenation system and a portable system for ambulation, with 16 (64%) using stationary and portable concentrators and 9 (36%) using a stationary reservoir and portable liquid oxygen bag. Oxygenation settings at rest and while walking were determined at baseline. Subjects were maintained on the previous combined system for 1 week and then switched to the portable oxygen concentrator for 1 week. Mean S(pO2) over 24 h was calculated using the software in the oximeter, and compliance was monitored (Visionox). Low S(pO2) (< 90%) was significantly more frequent during use of the portable concentrator alone than with the combined system (37.1% vs 18.4%, P < .05). The portable system alone was preferred by 43% of subjects, and the combined system was preferred by 36%, whereas 21% were not sure. Subjects preferred using a single portable oxygenation system both at home and during ambulation. Portable systems alone, however, did not supply the same levels of oxygenation as the combination of fixed and portable systems. Before the widespread adoption of portable systems as a single device, additional studies are needed to determine best-practice protocols for adjustment of daytime and nighttime oxygenation settings. (ClinicalTrials.gov registration NCT02079753).

Water absorption kinetics in different wettability conditions studied at pore and sample scales in porous media by NMR with portable single-sided and laboratory imaging devices

Peak cough flow (PCF) measurements can be used as indicators of cough effectiveness. Portable peak flow meters and spirometers have been used to measure PCF, but little is known about their accuracy compared to pneumotachograph systems. The aim of this study was to compare the accuracy of four portable devices (Mini–Wright and Assess peak flow meters, SpiroUSB and Microlab spirometers) in measuring PCF with a calibrated laboratory based pneumotachograph system. Twenty healthy volunteers (mean (SD) age 45 (16) years) coughed through a pneumotachograph connected in series with each portable device in turn, and the differences in PCF readings were analysed. In addition, mechanically generated flow waves of constant peak flow were delivered through each device both independently and when connected in series with the pneumotachograph. Agreement between PCF readings obtained with the pneumotachograph and the portable devices was poor. Peak flow readings were on average lower by approximately 50 L min−1 when measured using the portable devices; 95% limits of agreement spanned approximately 150 L min−1. The findings highlight the potential for inaccuracy when using portable devices for the measurement of PCF. Depending on the measurement instrument used, absolute values of PCF reported in the literature may not be directly comparable.

Artificial intelligence (AI) can detect left ventricular systolic dysfunction (LVSD) from electrocardiograms (ECGs). Wearable devices could allow for broad AI-based screening but frequently obtain noisy ECGs. We report a novel strategy that automates the detection of hidden cardiovascular diseases, such as LVSD, adapted for noisy single-lead ECGs obtained on wearable and portable devices. We use 385,601 ECGs for development of a standard and noise-adapted model. For the noise-adapted model, ECGs are augmented during training with random gaussian noise within four distinct frequency ranges, each emulating real-world noise sources. Both models perform comparably on standard ECGs with an AUROC of 0.90. The noise-adapted model performs significantly better on the same test set augmented with four distinct real-world noise recordings at multiple signal-to-noise ratios (SNRs), including noise isolated from a portable device ECG. The standard and noise-adapted models have an AUROC of 0.72 and 0.87, respectively, when evaluated on ECGs augmented with portable ECG device noise at an SNR of 0.5. This approach represents a novel strategy for the development of wearable-adapted tools from clinical ECG repositories.

The real-world effectiveness of the artificial intelligence model based on electrocardiogram (AI-ECG) signals from portable devices for detection of left ventricular systolic dysfunction (LVSD) requires further exploration. In this prospective, single-centre study, we assessed the diagnostic performance of AI-ECG for detecting LVSD using a six-lead hand-held portable device (AliveCor KardiaMobile 6L). We retrained the AI-ECG model, previously validated with 12-lead ECG, to interpret the 6-lead ECG inputs. Patients aged 19 years or older underwent six-lead ECG recording during transthoracic echocardiography. The primary outcome was the area under the receiver operating characteristic curve (AUROC) for detecting LVSD, defined as an ejection fraction below 40%. Of the 1716 patients recruited prospectively, 1635 were included for the final analysis (mean age 60.6 years, 50% male), among whom 163 had LVSD on echocardiography. The AI-ECG model based on the six-lead portable device demonstrated an AUROC of 0.924 [95% confidence interval (CI) 0.903-0.944], with 83.4% sensitivity (95% CI 77.8-89.0%) and 88.7% specificity (95% CI 87.1-90.4%). Of the 1079 patients evaluated using the AI-ECG model based on the conventional 12-lead ECG, the AUROC was 0.962 (95% CI 0.947-0.977), with 90.1% sensitivity (95% CI 85.0-95.2%) and 91.1% specificity (95% CI 89.3-92.9%). The AI-ECG model constructed with the six-lead hand-held portable ECG device effectively identifies LVSD, demonstrating comparable accuracy to that of the conventional 12-lead ECG. This highlights the potential of hand-held portable ECG devices leveraged with AI as efficient tools for early LVSD screening.

Objective: This study aimed to demonstrate the accuracy of a portable device for measuring nasal and bronchial fractional exhaled nitric oxide (nFeNO and FeNO) as an alternative method to replace a high-cost multiple flow device in subjects with allergic rhinitis (AR) . Methods: It was a descriptive and comparative study. The healthy subjects (control group), subjects with AR (AR group) and those with AR and asthma (AR-A group) were enrolled in this study. They underwent nasal and bronchial FeNO measurements by both fixed flow NObreath ® connected to nasal mask (for nFeNO) and without mask (for FeNO) and multiple flows HypAir FeNO ® . Results: There were 153 subjects recruited during the study period, including 63 healthy subjects and 90 subjects with AR and AR-A. There were no statistically significant differences in anthropometric characteristics between study groups. The concentrations of nasal FeNO and bronchial FeNO measured by a portable device in subjects with AR were higher than in healthy subjects: 76.0 ± 50.7 ppb vs 36.0 ± 28.1 ppb ( P &lt; 0.01), and 32.3 ± 15.4 ppb vs 9.2 ± 5.6 ppb ( P &lt; 0.001). There was a weak correlation between nasal FeNO measured by portable devices and multiple flow devices. Conclusions: The portable device is useful in measuring nasal FeNO in subjects with AR. The advantages of a low-cost and accurate portable device may help it be used in primary care in the management of subjects with allergic rhinitis and asthma

Paper-based sensors for rapid important biomarkers detection

Workshop Synthesis: Conducting Travel Surveys using Portable Devices- Challenges and Research Needs

Portable devices (such as personal digital assistants and laptops with wireless connectivity) are becoming ubiquitous. As their functionality and capabilities increase, their energy consumption requirements also increase. Yet, these devices have to operate on limited batteries. In order to maximize the battery lifetime, it is necessary to optimize the use of energy at various components of such a device. In this paper, we consider a single portable device operating on a limited battery that transmits information over an interference-limited wireless channel. We seek to optimize the power consumption on the communication radio in this device, by controlling both the operation mode and the transmission power. We model the general problem using dynamic programming, obtain the optimal solutions for insightful special cases and explore various design tradeoffs. Our work provides an analytical framework for stochastic modeling and optimization of energy spent for communications in battery-operated portable devices.

Recently, because the portable devices became popular, it is easily to see that each person carries more than just one portable device and the use of the smartphone stretches as time goes by. After the smartphone has propagated rapidly, the total usage of the smartphone applications has also increased. But still, each application store has a different platform to develop and to apply an application. The application store is divided into two big markets, the Android and the Apple. So the developers have to develop their application by using these two different platforms. Developing into two different platforms almost makes a double development cost. And for the other platforms, the weakness is, which still have a small market breadth like Bada is not about the cost, but about drawing the proper developers for the given platform application development. The web application is rising up as the solution to solve these problems, reducing the cost and time in developing applications for every platform. For web applications don`t need to make a vassal relationship with application markets platform. Which makes it possible for an application to operate properly in every portable devices and reduces the time and cost in developing. Therefore, all of the application markets could be united into one big market through a protocol which will connect each web applications market. But, still there is no standard for the web application store and no current web application store is possible to interlock with other web application stores. In this paper, we are trying to suggest a protocol by developing a prototype and prove that this protocol can supplement the current weakness.

A portable accelerometer-based device which used to detect small displacement is designed, and a novel method of acceleration signal processing for small displacement measurement is provided. The system consists of a low-cost tri-axial accelerometer, a microprocessor, and a wireless data transfer module. Accelerometer is sensitive to noise so that it is essential to design a Butterworth low-pass infinite impulse response digital filter for denoising. After signal processing, small displacement calculation method is used to obtain movement detection and estimation. Our experiments show that the method of signal processing for the accelerometer embedded in portable devices is effective, and the portable accelerometer-based device can be used to get small displacement of measured object.

Developing a facile, cost-saving, and environment-friendly method for fabricating a multifunctional humidity sensor is of great significance to expand its practical applications. However, most humidity sensors involve a complex fabrication process, resulting in their high cost and narrow application fields. Herein, a multifunctional paper-based humidity sensor with many advantages is proposed. This humidity sensor is fabricated using conventional printing paper and flexible conductive adhesive tape by a facile pasting method, in which the paper is used as both the humidity-sensing material and the substrate of the sensor. Owing to the moderate hydrophilicity of the paper and the rational structure design of the paper-based humidity sensor, the sensor exhibits an excellent humidity-sensing response of more than 103 as well as good linearity ( R2 = 0.9549) within the humidity range from 41.1 to 91.5% relative humidity. Furthermore, the paper-based humidity sensor has good flexibility and compatibility, endowing it with multifunctional applications for breath rate, baby diaper wetting, noncontact switch, skin humidity, and spatial localization monitoring. Although the resistance of the paper-based humidity sensor is relatively large, the humidity-sensing response signals of the sensor can be conveniently processed by the designed signal processing system. The readily available starting materials and facile fabrication technique provide useful strategies for the development of multifunctional humidity sensors.

Determinación ambulatoria de glucohemoglobina en el seguimiento y el control de la diabetes mellitus: revisión sistemática de la literatura