Smartphone-Powered Electrochemical Dongle for Point-of-Care Monitoring of Blood β-Ketone

DNA origami-based aptasensors

Traditional analytical techniques face many limitations such as time-consuming process, complicated sample preparation, high consumption of reagents and need for expensive equipment. So, it is important that simple, rapid and sensitive detection methods are introduced. Nucleic acids-based assays, particularly aptamers, have a great impact on modern life sciences for biological analysis and target detection. Aptamer-based biosensors with unique recognition properties including high specificity and affinity, rapid response and simple fabrication have attracted much attention. It is believed that two- and three-dimensional structures, sometimes referred to as DNA origami, using DNA aptamers can show more selective binding affinity and better stability over other nucleic acids forms. In this review, we will focus on recent advances in the development and uses of electrochemical and optical DNA origami-based aptasensors to supply readers with a comprehensive understanding of their improvements. Also, the challenges and awards of these approaches are discussed.

Combination of medical and health care based on digital smartphone-powered photochemical dongle for renal function management

Currently, the global healthcare market is increasing at high speed with the impendent global aging issue. Healthcare Industry 4.0 has emerged as an efficient solution towards the aging issue since it was integrated with ubiquitous medical sensors, big health processing platform, high bandwidth, speed technologies, and medical services, etc. It is believed to fulfil the requirement of the tremendously growing health market. The acquisition of medical data acts as the dominant precondition to implement the Healthcare Industry 4.0. In the same way, the widely available smartphone could serve as the best biomedical information collect station. In this study, a smartphone-powered photochemical dongle is demonstrated to precisely estimate blood creatinine from the fingertip blood, which works as a highly compact reflectance spectral analyzer with an enzymatically dry chemical test strip. Comparing with conventional laboratory facility for the evaluation and treatment of chronic kidney disease (CKD), it implemented the platform of point care with agreed accuracy. In order to estimate the efficiency of treatment and recovery of the CKD, the proposed photochemical dongle would provide a flexible and rapid platform for point of care. Furthermore, the proposed measured technology is very promising method for remote CKD management.

Noncontact RF Vital Sign Sensor for Continuous Monitoring of Driver Status

In this paper, a radio frequency vital sign sensor based on double voltage-controlled oscillators (VCOs) combined with a switchable phase-locked loop (PLL) is proposed for a noncontact remote vital sign sensing system. Our sensing system primarily detects the periodic movements of the human lungs and the hearts via the impedance variation of the resonator. With a change in impedance, both the VCO oscillation frequency and the PLL feedback voltage also change. Thus, by tracking the feedback voltage of the PLL, breath and heart rate signals can be acquired simultaneously. However, as the distance between the body and the sensor varies, there are certain points with minimal sensitivity, making it is quite difficult to detect vital signs. These points, called impedance null points, periodically occur at distances proportional to the wavelength. To overcome the impedance null point problem, two resonators operating at different frequencies, 2.40 and 2.76 GHz, are employed as receiving components. In an experiment to investigate the sensing performance as a function of distance, the measurement distance was accurately controlled by a linear actuator. Furthermore, to evaluate the sensing performance in a real environment, experiments were carried out with a male and a female subject in a static vehicle. To demonstrate the real-time vital sign monitoring capability, spectrograms were utilized, and the accuracy was assessed relative to reference sensors. Based on the results, it is demonstrated that the proposed remote sensor can reliably detect vital signs in a real vehicle environment.

Smartphone-imaged microfluidic biochip for measuring CD64 expression from whole blood

Sepsis, a life-threatening syndrome that contributes to millions of deaths annually worldwide, represents a moral and economic burden to the healthcare system. Although no single, or even a combination of biomarkers has been validated for the diagnosis of sepsis, multiple studies have shown the high specificity of CD64 expression on neutrophils (nCD64) to sepsis. The analysis of elevated nCD64 in the first 2-6 hours after infection during the pro-inflammatory stage could significantly contribute to early sepsis diagnosis. Therefore, a rapid and automated device to periodically measure nCD64 expression at the point-of-care (POC) could lead to timely medical intervention and reduced mortality rates. Current accepted technologies for measuring nCD64 expression, such as flow cytometry, require manual sample preparation and long incubation times. For POC applications, however, the technology should be able to measure nCD64 expression with little to no sample preparation. In this paper, we demonstrate a smartphone-imaged microfluidic biochip for detecting nCD64 expression in under 50 min. In our assay, first unprocessed whole blood is injected into a capture chamber to immunologically capture nCD64 along a staggered array of pillars, which were previously functionalized with an antibody against CD64. Then, an image of the capture channel is taken using a smartphone-based microscope. This image is used to measure the cumulative fraction of captured cells (γ) as a function of length in the channel. During the image analysis, a statistical model is fitted to γ in order to extract the probability of capture of neutrophils per collision with a pillar (ε). The fitting shows a strong correlation with nCD64 expression measured using flow cytometry (R² = 0.82). Finally, the applicability of the device to sepsis was demonstrated by analyzing nCD64 from 8 patients (37 blood samples analyzed) along the time they were admitted to the hospital. Results from this analysis, obtained using the smartphone-imaged microfluidic biochip were compared with flow cytometry. Again, a correlation coefficient R² = 0.82 (slope = 0.99) was obtained demonstrating a good linear correlation between the two techniques. Deployment of this technology in ICU could significantly enhance patient care worldwide.

Flexible Antenna Design on PDMS Substrate for Implantable Bioelectronics Applications

In the current field of biomedical engineering, the research on implanted antennas has attracted more and more attention. This paper presents a flexible terrestrial radiating antenna with circular polarization characteristics that satisfy various requirements for biomedical implantable antennas. The new type of flexible material is adopted and a novel model is proposed. The square ground with small gap is implemented in the proposed antenna. The passive components can match the impedance and meet the requirements of the circular polarization wave. Simulation is carried out in a single layer tissue model to estimate the performance of the antenna and compared with multilayer tissue model. In addition, the flexible circularly polarized antenna has low profile characteristics and a wide axial ratio bandwidth of 250 MHz, ranging from 2.28 GHz to 2.53 GHz. This paper uses pork to simulate single layer and multi layer tissue model. The flexible circular polarized antenna prototype is placed in the organization model for performance simulation test, and the measurement impedance bandwidth of 500 MHz is realized in the industrial scientific medical frequency band of 2.4GHz-2.48 GHz. This article is protected by copyright. All rights reserved.

Advances in nanoplasmonic biosensors for clinical applications

Plasmonic biosensors can be conveniently used as portable diagnostic devices for attaining timely and cost-effective clinical outcomes. Nanoplasmonics technology opens the way for sensor miniaturization, multiplexing and point of care testing.

A novel rhodamine-based fluorescent probe for selective detection of ClO– and its application in living cell imaging

A novel fluorescent rhodamine-based probe L for selective responding to ClO– has been synthesized and characterized. The spectroscopy showed that probe L can detect ClO– in aqueous solution without interaction with other interfering ions, and the detection is also evident by the colour change from colourless to reddish purple under white light. The remarkable fluorescence enhancement showed the high selectivity and sensitivity of probe L for the detection of ClO–. Furthermore, probe L was applied to intracellular fluorescent imaging of HeLa cells treated with ClO– and MTT assay showed nontoxicity in living cells.

Electrochemical immunosensor utilizing electrodeposited Au nanocrystals and dielectrophoretically trapped PS/Ag/ab-HSA nanoprobes for detection of microalbuminuria at point of care

In this study, we have fabricated a simple disposable electrochemical immunosensor for the point of care testing of microalbuminuria, a well-known clinical biomarker for the onset of chronic kidney disease. The immunosensor is fabricated by screen-printing carbon interdigitated microelectrodes on a flexible plastic substrate and utilizes electrochemical impedance spectroscopy to enable direct and label free immunosensing by analyzing interfacial changes on the electrode surface. To improve conductivity and biocompatibility of the screen-printed electrodes, we have modified it with gold nanoparticles, which are electrodeposited using linear sweep voltammetry. To enable efficient immobilization of HSA antibodies, we have developed novel PS/Ag/ab-HSA nanoprobes (polystyrene nanoparticle core with silver nanoshells covalently conjugated to HSA antibodies), and these nanoprobes are trapped on the electrode surface using dielectrophoresis. Each immunosensor has two sensing sites corresponding to test and control to improve specificity by performing differential analysis. Immunosensing results show that the normalized impedance response is linearly dependent on albumin concentration in the clinically relevant range with good repeatability. We have also developed a portable impedance readout module that can analyze the data obtained from the immunosensor and transmit it wirelessly for cloud computing. Consequently, the developed immunosensing platform can be extended to the detection of a range of immunoreactions and shows promise for point of diagnosis and public healthcare monitoring.

A Numerical Model of Blood Flow Velocity Measurement Based on Finger Ring

Aiming to measure the blood flow velocity in a finger, a novel noninvasive method, i.e., a ring with a heat source chip and a temperature sensor, is designed in this paper. The heat source chip is used to heat the finger and generate heat diffusion between the chip and the temperature sensor. And the temperature sensor is designed to measure the temperature difference. Since the blood flow is the main medium of heat diffusion in bodies, part from the heat energy in the tissue will be taken away by the flowing blood. Therefore, the blood flow velocity can be acquired via its relationship with the temperature difference. Compared to the ultrasound Doppler method and the laser Doppler method, the proposed method guarantees a more convenient operation in more flexible work sites. We also analyze the theory between heat transfer and laminar flow. Finally, several simulations are conducted, and the influence of the relevant factors (i.e., the number of blood vessels, the radius, etc.) corresponding to the simulation results is also discussed.

Smartphone-based differential pulse amperometry system for real-time monitoring of levodopa with carbon nanotubes and gold nanoparticles modified screen-printing electrodes

Parkinson's disease caused by lack of dopamine in brain is a common neurodegenerative disorder. The traditional treatment is to replenish levodopa since it could pass through blood brain barrier and form dopamine. However, its accumulation can cause patients' movement disorders and uncontrollable emotion. Therefore, it is critical to control the levodopa dosage accuracy to improve the curative effect in clinical. In this study, a smartphone-based electrochemical detection system was developed for rapid monitoring of levodopa. The system involved a disposable sensor, a hand-held electrochemical detector, and a smartphone with designed application. Single-wall carbon nanotubes and gold nanoparticles modified screen-printed electrodes were used to convert and amplify the electrochemical current signals upon presence of levodopa molecules. The electrochemical detectors were used to generate electrochemical excitation signals and detect the resultant currents. Smartphone was connected to the detector, which was used to control the detector, calculate data, and plot graph in real-time. The smartphone-based differential pulse amperometry system was demonstrated to monitor levodopa at concentrations as low as 0.5 µM in human serum. Furthermore, it has also been verified to be able to distinguish levodopa from other representative substances in the body. Therefore, its performance was more sensitive and rapid than electrochemical workstation. With these advantages, the system can be used in the field of point-of-care testing (POCT) to detect levodopa and provide the possibility to solve clinical demand for levodopa detection.

Numerical and experimental investigation of 'water fan' effect due to electrohydrodynamic force in a microchamber

Electrohydrodynamics is commonly used in microfluidics to control and manipulate the fluid. Though there are studies on the rotation flow in suspended films, the thin film liquid is easily broken and cannot last long hence not applicable in specific applications. Here, we established a three-dimensional microchamber embedded with two pairs of microelectrodes to investigate the rotational phenomenon of bulk of liquid which we called 'water fan' effect based on the electrohydrodynamics force. When proper voltages were applied on these microelectrodes, the tornado-like rotation would be generated. Both the numerical and experimental results showed that the controllable and continuous rotation could be achieved in the microchamber. In addition, the concentration effect resulting from the rotation flow was also observed. The proposed method offers great promises in providing theoretical and practical guideline in microfluidic devices for mixing, separating, and cooling applications.

Blood glucose monitoring with smartphone as glucometer

In this short communication, we redefine smartphone and enable it to monitor blood glucose as glucometer. The proposed smartphone is not only a mobile phone but also a medical device-glucometer. An electrometer module, acquiring the electrochemical current from the disposable enzymatic test strip on which a 0.5 μL human peripheral whole blood drop is placed, was integrated in the smartphone. The medical smartphone is capable of directly measuring blood glucose concentration and uploading into personal health center by the 4G mobile communication internet.

Blood Cholesterol Monitoring With Smartphone as Miniaturized Electrochemical Analyzer for Cardiovascular Disease Prevention

Currently, cardiovascular diseases become one of the major threat to human's life. The early prevention of cardiovascular diseases plays a critical role in the healthcare engineering. Point of care monitoring the blood lipid level is capable of making the positive contribution to the prevention of cardiovascular disease. Ubiquitous smartphones paved the way as the flexible and widespread platform for the interaction of various health information. In this manuscript, we report the world's first medical smartphone as an electrochemical analyzer for blood lipid monitoring. Integrating an electrochemical analyzer into a smartphone allows us to measure the current generated by the enzymatic reaction with the total cholesterol test strip. The disposable test strip is used to convert the biochemical signal to electrical signal through the electrochemical reaction. The proposed medical smartphone can provide accurate evaluation of patient's blood lipid level as compared to the clinical biochemical analyzer. The proposed medical smartphone system is a promising platform as a point-of-care device for blood total cholesterol (TC) monitoring, which can be applied for long-term prevention of cardiovascular disease due to its portability, reliability, lower cost, convenience, and internet-based medical data interaction.

Microfluidic Mass Production of Stabilized and Stealthy Liquid Metal Nanoparticles

Functional nanoparticles comprised of liquid metals, such as eutectic gallium indium (EGaIn) and Galinstan, present exciting opportunities in the fields of flexible electronics, sensors, catalysts, and drug delivery systems. Methods used currently for producing liquid metal nanoparticles have significant disadvantages as they rely on both bulky and expensive high-power sonication probe systems, and also generally require the use of small molecules bearing thiol groups to stabilize the nanoparticles. Herein, an innovative microfluidics-enabled platform is described as an inexpensive, easily accessible method for the on-chip mass production of EGaIn nanoparticles with tunable size distributions in an aqueous medium. A novel nanoparticle-stabilization approach is reported using brushed polyethylene glycol chains with trithiocarbonate end-groups negating the requirements for thiol additives while imparting a "stealth" surface layer. Furthermore, a surface modification of the nanoparticles is demonstrated using galvanic replacement and conjugation with antibodies. It is envisioned that the demonstrated microfluidic technique can be used as an economic and versatile platform for the rapid production of liquid metal-based nanoparticles for a range of biomedical applications.

The Insertion Mechanism of a Living Cell Determined by the Stress Segmentation Effect of the Cell Membrane during the Tip-Cell Interaction

Atomic force microscopy probes are proved to be powerful tools to measure and manipulate the individual cell, providing potential applications for the controlled drug/protein delivery. However, the measured insertion efficiency varies dramatically from 20 to 80%, in some cases, the nanotip can never penetrate the cell membrane no matter how much force is applied to it. Thus, the insertion mechanism of a living cell during the tip-cell interaction must be thoroughly investigated before this technology comes into practical applications. In this work, a multistructural cell model is established to study the tip-membrane interaction. The simulation results show that the stress of the cell membrane can be divided into two stages by the stress segmentation point S. After point S, the stress of the cell membrane increases slightly and most of the indentation force is allocated to the cytoskeleton. This phenomenon is called "stress segmentation effect of the cell membrane," which confirms the hypothesis based on the experimental studies. Moreover, according to the experimental and numerical studies, the hypothesis of the stress segmentation effect also explains the reason that modifying the cell membrane or using the manmade sharpened nanotip can increase the insertion efficiency.

Biophysical measurement of red blood cells by laboratory on print circuit board chip

Microfluidic impedance pulse sensor has emerged as an easily handled and low-cost platform in the electrical analysis of biological cells. In the conventional method, impedance sensor demanded expensive patterning metal electrodes on the substrate, which are directly in touch with electrolytes in order to measure the microfluidic channel impedance change. In this article, a cost-effective microfluidic impedance sensor built upon a dielectric film coated printed circuit board is introduced. Impedance electrodes are protected by a dielectric film layer from electrochemical erosion between electrodes and electrolyte. Human red blood cells from adult and neonatal were utilized to demonstrate the feasibility of the proposed device in the electroanalysis of biological cells.

Smartphone-based analytical biosensors

With the rapid development, mass production, and pervasive distribution of smartphones in recent years, they have provided people with portable, cost-effective, and easy-to-operate platforms to build analytical biosensors for point-of-care (POC) applications and mobile health.