Sensors For Biomedical Applications Research Articles

Reconfigurable UWB Transceiver for Biomedical Sensor Application

This paper presented a new design of a reconfigurable ultra-wide band (UWB) transceiver for biomedical applications. The proposed transceiver was designed to cover the standard low band channel with a 525-MHz bandwidth, corresponding to the center frequencies of 3.5, 4, 4.5 GHz. The emitter is made up of a multi-band voltage-controlled oscillator (VCO), a D-latch, and a passive mixer. The receiver, based on a non-coherent IEEE 802.15.4a standard, consists of a reconfigurable low noise amplifier (LNA), a squarer, a low pass amplifier, and a high speed decision stage. The LNA uses a programmable current reuse topology to control the operation mode. This LNA was designed to operate in three sub-bands of low band UWB, UWB mode-1, UWB mode-2, and UWB mode-3. The multi-band pulse generator produces an output signal with a maximum power spectral density (PSD) of –43 dBm/MHz. It dissipates 9.66 mA from the 1.8-V power supply. The receiver power consumption is approximately equal to 15.56 mW. Simulation results show that this configuration can achieve a 200-Mbps data rate and −54-dBm@200Mbps receiving sensitivity. This topology was designed in 0.18 μm RF-CMOS technology.

On the Use of Knitted Antennas and Inductively Coupled RFID Tags for Wearable Applications.

Recent advancements in conductive yarns and fabrication technologies offer exciting opportunities to design and knit seamless garments equipped with sensors for biomedical applications. In this paper, we discuss the design and application of a wearable strain sensor, which can be used for biomedical monitoring such as contraction, respiration, or limb movements. The system takes advantage of the intensity variations of the backscattered power (RSSI) from an inductively-coupled RFID tag under physical stretching. First, we describe the antenna design along with the modeling of the sheet impedance, which characterizes the conductive textile. Experimental results with custom fabricated prototypes showed good agreement with the numerical simulation of input impedance and radiation pattern. Finally, the wearable sensor has been applied for infant breathing monitoring using a medical programmable mannequin. A machine learning technique has been developed and applied to post-process the RSSI data, and the results show that breathing and non-breathing patterns can be successfully classified.

Synthesis and Complexation of Well-Defined Labeled Poly(N,N-dimethylaminoethyl methacrylate)s (PDMAEMA)

We present the synthesis and characterization of well-defined polycationic copolymers containing thiazole dyes in the side chain. Atom transfer radical polymerization (ATRP) was used for the copolymerization of 3-azidopropyl methacrylate (AzPMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA) of different composition. Thiazole-based alkyne-functionalized dyes (e.g., 5-methyl-4-(prop-2-yn-1-yloxy)-2-(pyridin-2-yl)thiazole, (MPPT)) were afterwards covalently attached using copper catalyzed azide alkyne cycloadditions (CuAAC) reaching contents of up to 9 mol % dye. Subsequent quaternization of the tertiary nitrogen of DMAEMA with strong methylation agents (e.g., methyl iodide) led to permanently charged polyelectrolytes. The materials were characterized by size exclusion chromatography, as well as NMR- and UV/VIS-spectroscopy. Particular attention is paid to the spectroscopic properties of the dyes in the side chain upon environmental changes such as pH and salinity. We anticipate the application of such precisely functionalized polyelectrolytes as temperature- and pH-responsive sensors in biomedical applications, e.g., within interpolyelectrolyte complexes. Concerning the latter, first complex formation results are demonstrated.

Addition of molybdenum into amorphous glass‐coated microwires usable as temperature sensors in biomedical applications

Compared to other sensors, such as radio‐frequency identification sensors, microwires have a significant advantage due to their small dimensions and contact‐free reading. The most important advantage is that a microwire is considered to be a biocompatible material due to the glass‐coating insulator. This is particularly applicable in various titanium implants (dental, knee joint, replacement of damaged skull part, repair of the femur, etc.). The temperature dependence of the switching field can be employed to monitor inflammatory processes. In this contribution we present the influence of molybdenum (Mo) content on the magnetic properties and thermal treatment in order to obtain a strong variation of the switching field to temperature. We show that stress annealing of a FeMo9BCu microwire at 775 K under an applied axial stress of 309 MPa leads to the strongest variation in a temperature range from 300 to 315 K, which is highly desirable for biomedical applications.

Development of a Human Upper Limb Volume Sensor for Biomedical Applications

Muscle volume is an important indicator for the strength of the muscle. Many biomedical scientists use the muscle volume as an index for the athlete muscle power and also the health condition of the patients with muscular problems. The purpose of this study is to develop a sensor to easily and accurately gauge human upper limb muscle volume for biomedical applications. The developed sensor has many advantages for protable measurement of the human limb volume.

Ag-TiNx electrodes deposited on piezoelectric poly(vinylidene fluoride) for biomedical sensor applications

Electroactive polymers are one of the most interesting class of polymers used as smart materials in various applications, such as the development of sensors and actuators for biomedical applications in areas such as smart prosthesis, implantable biosensors and biomechanical signal monitoring, among others. For acquiring or applying the electrical signal from/to the piezoelectric material, suitable electrodes can be produced from Ti based coatings with tailored multifunctional properties, e.g., electrical conductivity and antibacterial characteristics, through Ag inclusions. TiN is a good candidate for this application since it is electrically conductive and shows superior chemical stability in relation to pure Ti, being also biocompatible.

Deep ultraviolet laser direct write for patterning sol-gel InGaZnO semiconducting micro/nanowires and improving field-effect mobility.

Deep-UV (DUV) laser was used to directly write indium-gallium-zinc-oxide (IGZO) precursor solution and form micro and nanoscale patterns. The directional DUV laser beam avoids the substrate heating and suppresses the diffraction effect. A IGZO precursor solution was also developed to fulfill the requirements for direct photopatterning and for achieving semi-conducting properties with thermal annealing at moderate temperature. The DUV-induced crosslinking of the starting material allows direct write of semi-conducting channels in thin-film transistors but also it improves the field-effect mobility and surface roughness. Material analysis has been carried out by XPS, FTIR, spectroscopic ellipsometry and AFM and the effect of DUV on the final material structure is discussed. The DUV irradiation step results in photolysis and a partial condensation of the inorganic network that freezes the sol-gel layer in a homogeneous distribution, lowering possibilities of thermally induced reorganization at the atomic scale. Laser irradiation allows high-resolution photopatterning and high-enough field-effect mobility, which enables the easy fabrication of oxide nanowires for applications in solar cell, display, flexible electronics, and biomedical sensors.

A low power, highly stabilized three electrode potentiostat for biomedical implantable systems

This paper presents a low-power three-electrode potentiostat for biomedical implantable glucose sensor applications. Low power consumption is one of the most important criteria for a wireless impla...

Hassle-Free Vitals: BioWireleSS for a Patient-Centric Health-Care Paradigm

Continuous monitoring of vital information via a wireless medium has become an integral part of next-generation health-care technologies. The benefits of a wireless monitoring technique include facilitating in-home care services, reduction of the cost of frequent visits to hospitals, and lightening of the burden to the elderly persons. The development of miniature, lightweight, and energy-efficient circuit solutions for biomedical sensor applications has been made possible by the tremendous recent advancements in health-care monitoring technologies, micro- and nanofabrication processes, and wireless communications. Exuberant growth of the wireless sensor networks has opened up a new and innovative application of wireless technology in health care. The advancement of wireless technology has led to the development of the recently proposed comprehensive patient monitoring systems such as wireless body area network (WBAN) and body sensor network (BSN). Implantable and wearable sensors are integral components of these networks and are employed for monitoring various levels of physiological activities. Wireless sensor technology provides an effective tool for instant access to patient data, laboratory test results, and clinical histories as well as insurance information, thereby ensuring immediate health care in case of emergency, eliminating the lengthy clinical decision. This biomedical wireless technology has resulted in a new health-care concept known as telemedicine, which facilitates the monitoring of in-home patient care by incorporating smart medical devices and WBANs. In this scheme, implantable and wearable sensors are placed within the vicinity of the patient's body and various physiological parameters are monitored and transmitted wirelessly to a nearby hub station and subsequently to the remote health-care provider via a secure wireless communication network. The telemedicine platform can also be configured for identification of the object location, medicine reminder, or emergency alert in case of any sign of fatal disease. As a result of the recent developments in biomedical wireless technologies, the traditional clinic-centric health care is giving way to a patient-care centric health-care concept. This translational health-care concept facilitates the multidirectional integration of basic research, patient-oriented research, and population-based research, with the long-term aim of improving the health of the public. However, the successful integration of this new health-care paradigm hinges on the proper interpretation, storage, and dissemination of the large data sets generated by the all implantable and wearable devices within the wireless network.

Synergistic Action of Alginate Chemical Reduction and Laser Irradiation for the Formation of Au Nanoparticles with Controlled Dimensions

Freestanding natural polymeric films with homogeneous dispersion of gold nanoparticles (Au NPs) are obtained via in situ reduction of gold(III) chloride trihydrate by sodium alginate (SA) biopolymer matrix, during water evaporation without the use of additional reducing agents. The size and size distribution of the prepared Au NPs can be tuned by changing the concentration of the precursor and/or the procedure of the films’ preparation. The nanocomposite films after preparation are stable in ambient conditions and can be used without the need of further processing, or can be redissolved in water. In the case of water dissolution, the aqueous solutions are irradiated with UV laser pulses turning the previously formed Au NPs into smaller ones with narrow size distributions through photofragmentation. This technique is proposed as a green way of synthesizing Au NPs of tunable size in aqueous solution of alginate, or incorporated in alginate freestanding polymeric films, that due to their biocompatibility can be used as passive labels or active sensors in biomedical applications.

A Wafer-Level Sn-Rich Au—Sn Bonding Technique and Its Application in Surface Plasmon Resonance Sensors

Sn-rich Au—Sn solder bonding is systematically investigated. High shear strength (64MPa) and good hermeticity (a leak rate lower than 1 × 10−7 torr·l/s) are obtained for Au—Sn solder with 54 wt% Sn bonded at 310°C. The AuSn2 phase with the highest Vickers-hardness among the four stable intermetallic compounds of the Au—Sn system makes a major contribution to the high bonding strength. This bonding technique has been successfully used to package the Surface Plasmon Resonance (SPR) sensors. The Sn-rich Au—Sn solder bonding provides a reliable, low-cost, low-temperature and wafer-level hermetic packaging solution for the micro-electromechanical system devices and has potential applications in high-end biomedical sensors.

Fabrication of a novel laccase biosensor based on silica nanoparticles modified with phytic acid for sensitive detection of dopamine

The development of novel nanomaterials for the ultra-sensitive detection of biological species has received great attention. Herein we report the design and synthesis of phytic acid functionalized silica nanoparticles (SiO2-PA NPs) and their biomedical sensor application for sensitive detection of dopamine. The SiO2-PA NPs were characterized by transmission electron microscopy (TEM) and Energy dispersive X-ray spectrometer (EDS). The biocompatibility between SiO2-PA NPs and laccase was also investigated by circular dichroism (CD) spectra. Moreover, the novel laccase biosensor based on SiO2-PA NPs for sensitive detection of dopamine (DA) was fabricated, and the electrochemical properties of this laccase biosensor were investigated. The results showed the biosensor had good electrocatalytic activity toward DA with a wide linear range (0.99–103.10μM) and a low detection limit 0.26±0.003μM. It can be attributed to the good biocompatibility and nano-effect of SiO2-PA NPs. The biosensor was successfully tested for determination of DA in pharmaceutical and rabbit blood serum samples. The development of biomimetic materials science will offer a novel platform for application to substance detection.

Telemetric Model for Passive Resistive Sensors in Biomedical Applications

Abstract The present work describes a telemetric resistive sensor to be exploited in biomedical applications, in order to monitor vital parameters in real time. The corresponding telemetry technique is based on an impedance measurement performed at its input terminal and on a theoretical study which identifies a complex mathematical relation between sensor's resistance and impedance phase value at a specific frequency point. A model for this system is proposed, analysed and discussed, while the telemetric technique based on it is described.

Optimal PID control of a nano-Newton CMOS-MEMS capacitive force sensor for biomedical applications

This paper presents closed loop simulation of a CMOS-MEMS force sensor for biomedical applications employing an optimal proportional-integral-derivative controller. Since the dynamic behavior of the sensor under investigation is nonlinear the iterative feedback tuning approach was proposed for optimal gains tuning of the proposed controller. Simulation results presented in this research illustrate that the proposed controller suppresses the undesired in-plane vibration induced by environment or gripper 40 times faster than the nonlinear controller proposed in the literature. To suppress the maximum input disturbance the maximum voltage was approximately 18 V which was less than the pull-in voltage of 30 V. The proposed controller is served to actuate two stator fingers adjacent to a rotor finger in order to provide both the attractive and repellent forces during manipulation. Employing the proposed mechanism not only resolves the drawbacks corresponding to the nonlinear controller presented in the literature but also improves its performance of the closed loop system by using the complete nonlinear dynamics of the force sensor. Also, applying complete non-linear dynamic of model improves the performance of controller and is one of superior features of proposed PID controller in comparison with the classical controller presented in literature.

Design of Portable Digital Microscope by Using Complementary-Metal-Oxide-Semiconductor Image Sensor for Biomedical Applications

Design of Portable Digital Microscope by Using Complementary-Metal-Oxide-Semiconductor Image Sensor for Biomedical Applications

Self-Assembly of DNA Nanostructures on Electron Beam Lithographically Patterned Templates for Biomedical and Nanoelectronic Sensor Applications

We demonstrate that the controlled self-assembly of DNA nanostructures can happen on electron beam lithographically patterned surfaces at lower energy. The fluorescent dye coupled amine modified DNA nanostructures were selectively attached to the patterned glass substrates. The optimized binding interaction between self-assembled DNA nanostructures occurred preferably at lower beam energy due to the attractive energy between the pattern and DNAs. Patterns containing self-assembled DNA molecules with dimensions as small as 2 nm in height and 68 nm in width have been successfully demonstrated. The periodicity in DNA self-assembly was observed. This technology of combination of “top-down” fabrication and “bottom-up” self-assembly may find use wherever there is a need to attach self-assembled DNA molecules in a nanometer scale patterned surface for various applications.

Digital Signal Processing by Virtual Instrumentation of a MEMS Magnetic Field Sensor for Biomedical Applications

We present a signal processing system with virtual instrumentation of a MEMS sensor to detect magnetic flux density for biomedical applications. This system consists of a magnetic field sensor, electronic components implemented on a printed circuit board (PCB), a data acquisition (DAQ) card, and a virtual instrument. It allows the development of a semi-portable prototype with the capacity to filter small electromagnetic interference signals through digital signal processing. The virtual instrument includes an algorithm to implement different configurations of infinite impulse response (IIR) filters. The PCB contains a precision instrumentation amplifier, a demodulator, a low-pass filter (LPF) and a buffer with operational amplifier. The proposed prototype is used for real-time non-invasive monitoring of magnetic flux density in the thoracic cage of rats. The response of the rat respiratory magnetogram displays a similar behavior as the rat electromyogram (EMG).

Distinguished Invited Speaker--Self-Assembly of Nanostructures On Electron Beam Lithographically Patterened Templates for Biomedical and Nanoelectronic Sensor Applications

not Available.

Immobilization of metal nanoparticles on polyurethane membranes: synthesis and electrical properties

AbstractAg and Cu nanoparticles were immobilized into crosslinked polyurethane (PU) membranes by taking advantage of the swelling characteristics of the membranes. The formation, shape and size of the nanoparticles inside the post‐swollen PU membranes were observed by transmission electron microscopy and atomic force microscopy. X‐ray diffraction indicated the presence of the pure Ag and Cu embedded in the amorphous PU matrix. Because of their compatibility, the nanoparticles improved the thermal stability and increased the glass transition temperature of PU. The membranes exhibited interesting conducting behavior with increasing temperature. The metal immobilization increased the ionic conductivity which further increased with temperature, with an activation energy of 0.15 eV indicating a thermally activated conduction mechanism. The optical and electrical properties of these starch‐based membranes can be utilized in the development of novel sensors for biomedical applications. Copyright © 2012 Society of Chemical Industry

Low-energy Formulations of Support Vector Machine Kernel Functions for Biomedical Sensor Applications

Although physiologically-indicative signals can be acquired in low-power biomedical sensors, their accurate analysis imposes several challenges. Data-driven techniques, based on supervised machine-learning methods provide powerful capabilities for potentially overcoming these, but the computational energy is typically too severe for low-power devices. We present a formulation for the kernel function of a support-vector machine classifier that can substantially reduce the real-time computations involved. The formulation applies to kernel functions employing polynomial transformations. Using two representative biomedical applications (EEG-based seizure detection and ECG-based arrhythmia detection) employing clinical patient data, we show that the polynomial transformation yields accuracy performance comparable to the most powerful available transformation (i.e., the radial-basis function), and the proposed formulation reduces the energy by over 2500× in the arrhythmia detector and 9.3-198× in the seizure detector (depending on the patient).