Electronic Transducer Research Articles

High-Density Immobilization of Tobacco Mosaic Virus Nanotubes As Enzyme Nanocarriers Onto Field-Effect Biosensor Structures

Introduction Viruses are not only infectious agents, they are also known as promising functional building blocks for application in nano- and biotechnologies. The tobacco mosaic virus (TMV) was the first studied plant virus and is widely distributed; it infects vegetables, like tomato, bell pepper, beans and other members of the family Solanaceae, while it is totally harmless for mammals [1]. It is one of the most studied plant viruses and its genome is completely sequenced, whereby genetical and chemical modification is easy. TMV has a nanotube-like shape with a length of 300 nm, an outer diameter of 18 nm and an inner diameter of 4 nm. Since it possesses a high chemical and physical robustness, it can be integrated with different electronic transducers for bio- and chemical sensing applications [2].Recently, we presented a TMV-based amperometric glucose biosensor [3] and a potentiometric penicillin biosensor [4]. TMV was used as enzyme nanocarrier for the enzyme glucose oxidase and penicillinase, respectively [3,4]. The sensitivity and detection limit of these biosensors, among others, depend on the density of TMVs on the sensor surface. The surface density of the immobilized TMVs is strongly influenced by the electrostatic interactions between the charged TMVs and sensor surface as well as by the inter-TMV-nanotubes repulsion, which could be changed by varying the pH value and the ionic strength of the TMV solution. In this study, we investigated an impact of the pH value and ionic strength of the TMV solution on the surface density of TMV nanotubes immobilized onto Ta2O5-gate capacitive field-effect electrolyte-insulator-semiconductor (EIS) sensors. Materials and Methods TMV particles modified with biotin-linker molecules (TMVBio), which serve as binding sites for streptavidin-conjugated enzymes, have been immobilized onto capacitive field-effect EIS sensors with Ta2O5 as transducer layer, as shown in Fig. 1. Immobilization was performed from TMVBiosolutions with different values of pH between pH 3.0 and pH 9.5 and ionic strength between 0.1 mM and 750 mM. The sensors have been electrochemically characterized before and after TMVBio immobilization by capacitance-voltage- and constant-capacitance methods, respectively. In addition, the density of the immobilized TMVs and morphology of the sensor surface has been investigated by means of scanning electron microscopy (SEM). Results and Conclusions The TMVBio density on the Ta2O5 sensor surface was influenced by varying the pH value (as exemplarily shown in Fig. 1) and ionic strength (not shown) of the TMVBio solution. The amplitude of the field-effect sensor signal correlates well with the density of the immobilized TMVBionanotubes. Thus, optimized conditions for the high-density immobilization of TMVBio nanotubes onto the Ta2O5 surface and thereby enhanced biosensing have been found. Details of the experiments and the obtained results will be presented and discussed.Figure 1: Measurement set-up with schematic layer structure of the capacitive EIS sensor modified with negatively charged TMVBio particles (a). SEM images of the Ta2O5-sensor surface modified with TMVBio nanotubes at pH 4.5 (b) and pH 7.0 (c), respectively. Acknowledgements The authors like to thank Dr. Claudia Koch and Rebecca Hummel, Stuttgart, for scientific and technical support.

Inlet Effect Caused by Multichannel Structure for Molecular Electronic Transducer Based on a Turbulent-Laminar Flow Model

The actual fluid form of an electrolyte in a molecular electronic converter is an important factor that causes a decrease in the accuracy of a molecular electronic transducer (MET) liquid motion sensor. To study the actual fluid morphology of an inertial electrolyte in molecular electron transducers, an inlet effect is defined according to the fluid morphology of turbulent-laminar flow, and a numerical simulation model of turbulent-laminar flow is proposed. Based on the turbulent-laminar flow model, this paper studies the variation of the inlet effect intensity when the thickness of the outermost insulating layer is 50 µm and 100 µm, respectively. Meanwhile, the changes of the inlet effect intensity and the error rate of central axial velocity field are also analyzed when the input signal intensity is different. Through the numerical experiment, it verifies that the thickness of the outermost insulating layer and the amplitude of the input signal are two important factors which can affect the inlet effect intensity and also the accuracy of the MET. Therefore, this study can provide a theoretical basis for the quantitative study on the performance optimization of a MET liquid sensor.

The Emergence of Insect Odorant Receptor-Based Biosensors.

The olfactory receptor neurons of insects and vertebrates are gated by odorant receptor (OR) proteins of which several members have been shown to exhibit remarkable sensitivity and selectivity towards volatile organic compounds of significant importance in the fields of medicine, agriculture and public health. Insect ORs offer intrinsic amplification where a single binding event is transduced into a measurable ionic current. Consequently, insect ORs have great potential as biorecognition elements in many sensor configurations. However, integrating these sensing components onto electronic transducers for the development of biosensors has been marginal due to several drawbacks, including their lipophilic nature, signal transduction mechanism and the limited number of known cognate receptor-ligand pairs. We review the current state of research in this emerging field and highlight the use of a group of indole-sensitive ORs (indolORs) from unexpected sources for the development of biosensors.

Study on Additional Dynamic Component of Electronic Current Transducer Based on Rogowski Coil and Its Test Approach

Electronic current transducers based on Rogowski coil are commonly used for power system protection. However, they may generate additional dynamic components in some cases that may cause misoperation of protection devices. In order to check the hidden danger of this undesired phenomenon, this article studies the transfer characteristics of Rogowski coil and proposes an approach to detect the possible occurrence of the additional dynamic component phenomenon. First, the root cause for the appearance of additional dynamic component is analyzed and investigated. Then, using the electromagnetic transient simulation modeling and variable delay scanning method, the simulation data of the grid operation are injected into the actual acquisition unit and the integral unit to obtain the output response of the current transducer. Therefore, the additional dynamic component phenomenon can be reproduced and identified. Finally, the test results of the application example demonstrate the effectiveness of the proposed method.

SU-8 inkjet patterning for microfabrication

Controlled SU-8 inkjet printing constitutes an attractive approach to realize electronic microstructures, MEMS, microfluidic devices or transducers. Indeed, inkjet printing is the most promising low-cost manufacturing process capable of depositing functional materials with high resolution, making this technique attractive for micrometric patterning. On the base of these premises, it's here presented the possibility to successfully print SU-8 complex patterned structures. Indeed, two different diluted SU-8 mixtures are successfully printed and a deep analysis on the effect of the physical parameters of the solvent is presented. The main challenges in SU-8 inkjet patterning are individuated and discussed through the evaluation of different shapes presenting critical printing aspects. In addition, some possible approaches to address such challenges are presented. Finally, the possibility to use inkjet printed SU-8 masks as templates for metal electrodeposition is demonstrated.

Organic Transistors Incorporating Lipid Monolayers for Drug Interaction Studies

AbstractCell membranes are fundamental for cellular function as they protect the cell and control passage in and out of the cell. Despite their clear significance, cell membranes are often difficult to study, due to their complexity and the lack of available technologies to interface with them and transduce their functions. Overcoming this complexity by developing simple, reductionist models can facilitate their study. Indeed, lipid layers represent a simplified yet representative model for a cell membrane. Lipid layers are highly insulating, a property that is directly affected by changes in lipid packing or membrane fluidity. Such physical changes in the membrane models can be characterized by coupling them with an electronic transducer. Herein, a lipid monolayer that is stabilized between two immiscible solvents is integrated with an organic electrochemical transistor, which is capable of operating in a biphasic solvent mixture. The platform is used to evaluate how lidocaine, a widely used anesthetic the working mechanism of which is still a matter of debate, interacts with the cell membrane. The present study provides evidence that the anesthetic directly interacts with the lipids in the membrane, affecting their packing and therefore the monolayer permeability. The proposed platform provides an elegant solution for studying compound–membrane interactions.

Feasibility of a Portable Abdominal Insufflation Device for Controlling Intraperitoneal Bleeding After Abdominal Blunt Trauma.

Uncontrolled bleeding contributes to 30% to 40% of trauma-related deaths and is the leading cause of potentially preventable deaths. Currently, there is no effective method available to first responders for temporary control of noncompressible intraabdominal bleeding while patients are transported to the hospital. Our previous studies demonstrated that abdominal insufflation provides effective temporary bleeding control. The study aims to prove the feasibility (insufflation to a target pressure) and safety (cardiovascular and respiratory effects) of a novel portable abdominal insufflation device (PAID) designed to control the intraperitoneal bleeding caused by abdominal trauma. The PAID prototype is based on a patented design and manufactured via additive manufacturing. PAID contains a 16-g CO2 cartridge and an electronic pressure transducer. PAID was tested on a bench top and a swine animal model. For the animal model study, the intraperitoneal pressure as well as cardiorespiratory parameters (hearth rate, SpO2 [peripheral capillary oxygen saturation], and blood pressure) were continuously monitored during the insufflation procedure. The prototype functioned according to specifications on both bench top and animal models. CO2 insufflation of the peritoneal cavity was delivered up the target 20 mm Hg and maintained for 30 minutes from 1 or 2 cartridges in the swine model. No intraoperative incidents were registered, and all the recorded physiological parameters were within normal limits. The PAID prototype is a feasible, easy to use device that provides quick, controlled, and safe insufflation of the peritoneal cavity. Future studies will focus on testing the next-generation, semiautomatic PAID prototype in a severe intraabdominal injury model.

Rotational Superconducting Gravitational Wave Detectors Based on Cooper-Pair Electronic Transducers

We report here on experimental and theoretical developments of a new method for gravitational wave (GW) detection. It is based on two principal steps: 1) Conversion of the GW action into rotational motion and 2) conversion of the rotational motion into an electric current. The ability to detect extremely tiny currents empowers this approach. Preliminary experiments confirm the theoretical expectations and suggest that gravitational waves beyond the reach of present interferometric devices can be detected.

Mechanism of Spasmogenic Activity Stimulated by Aqueous Ethanolic Leaf Extract of Mucuna pruriens on Isolated Uterine Muscle of Albino Rats

Aims: To investigate the effect of aqueous ethanolic leaf extract of this medicinal plant on isolated uterine smooth muscle strips of the rat and to determine its mechanism of action.
 Study Design: Laboratory-experimental design was used in this study.
 Place and Duration of Study: The study was carried out in the Department of Veterinary Physiology and Biochemistry of Michael Okpara University of Agriculture, Umudike, Nigeria, Department of Pharmacology and Toxicology of the Faculty of Pharmacy, University of Nigeria, Nsukka, and the Department of Veterinary Physiology and Pharmacology, University of Nigeria, Nsukka, Nigeria between June and October 2014.
 Methodology: Fresh leaves of Mucuna pruriens were identified and collected by a taxonomist from Nsukka, Nigeria. The leaves were then air dried and pulverized into powder. This was then subjected to cold extraction using petroleum ether (70-90) and 70% aqueous ethanol, after which the extract was left to dry at room temperature. Estrogenised uterine strips (12mm) were harvested from non-pregnant, sexually matured albino rats (180 g -250 g) and suspended in a 35ml organ bath containing Krebs’ physiological salt solution. The organ bath was connected to an isometric electronic force displacement transducer and a physiograph. Drugs such as Salbutamol, Isoprenaline, Adrenaline, Propranolol, Atipamezole and Prazosin were used as either agonists or antagonists to determine the mechanism of action of the extract. Atropine sulphate and Cyproheptadine were also used as test drugs. Concentrations of these drugs presented in the body of this work represent the final nutrient bath concentrations.
 Results: M. pruriens caused a dose -dependent increase in uterine muscle contraction with an EC50 of 0.88 mg/ml, n=4. The contraction was unaffected by atropine sulphate (0.042 µmol), but abolished by salbutamol (0.012-0.4 µmol), isoprenaline (0.06-0.23 µmol), and adrenaline (16 nmol). The uterine muscle contractions were enhanced by propranolol (1 µmol) in a dose- dependent manner. Prazosin (0.069-0.14 µmol) and atipamezole (3.3-13.7 nmol) were unable to abolish contractions stimulated by the extract. However, 0.2 µmol of cyproheptadine caused 80% suppression of the extract –induced uterine contraction
 Conclusion: It is concluded that aqueous ethanolic leaf extract of M. pruriens, has ability to cause uterine smooth muscle contraction hence, justifies its reported use traditionally as a uterine stimulant. This contraction is most likely exerted via the 5-HT receptor activation (activated by low concentrations of serotonin).

Multiphysics Simulation of Biosensors Involving 3D Biological Reaction–Diffusion Phenomena in a Standard Circuit EDA Environment

The topic of this paper is the development of biological models for 3D reaction–diffusion phenomena that can be used in any circuit electronic design automation environment for the simulation of biosensors. Biological systems that involve such 3D phenomena are described by partial differential equations. Our approach consists in discretizing these equations according to the finite-difference method and converting the resulting ordinary differential equations into an assembly of elementary electronic equivalent circuits that are directly simulated with SPICE. The main interest of this approach is the ability to couple such models with third-party SPICE models of electronic circuits, sensors, and transducers, i.e., models from any physical domain ruled by Kirchhoff laws, allowing modeling and simulation of any multi-physics systems in a conventional circuit design environment, here CADENCE. The tool is validated on simple problems for which analytical solutions are known. Then, the interest of the approach is illustrated on the study of a biosensor.

3D-microfabrication by two-photon polymerization of an integrated sacrificial stencil mask

This work aims at developing a new and unconventional Sacrificial Stencil Mask (SSM) technology by exploiting Two-Photon Polymerization (2PP) in an IP-L/SU-8 double layer resist system. The process consists of the sequential deposition of two different resists, such as SU-8 and IPL, onto the same glass substrate, followed by 2PP lithography and distinct development processes. The 2PP writing process was used to polymerize structures inside the top and bottom resist layers to form, in one single exposure process, both SSM and a permanent polymeric structure, in our case a plain pedestal. The top IPL resist was developed using Isopropyl Alcohol (IPA), which does not affect either exposed or un-exposed SU-8 regions. In this way, structures written into the bottom layer remained latent, while exposed areas of the top IPL resist, including the stencil mask, were developed. The realization of 3D stencil masks, designed to be anchored inside the un-exposed bottom layer, was combined with metal evaporation to demonstrate the deposition of a plain metal line through the stencil mask. The final development of the bottom layer led to the lift off of the sacrificial stencil mask, uncovering the underlying, permanent polymer-metal structure. The combination of sacrificial polymer structures with permanent ones opens new possibilities in 3D MEMS design, enabling the integration of distributed electronic transducers in flexible polymeric structures.

A highly porous and conductive composite gate electrode for OTFT sensors.

Ionic/protonic to electronic transducers based on organic thin film transistors have shown great promise for applications in bioelectronic interface devices and biosensors, and development of materials that exhibit mixed ionic/electronic conduction are an essential part of these devices. In this work, we investigated the proton sensing properties of an all solid-state and low voltage operating organic thin film transistor (OTFT) that uses the organic mixed conductor poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) as the gate electrode. To address the limited sensitivity due to the lack of porosity in PEDOT:PSS base sensors, we proposed a composite gate electrode material composed of PEDOT:PSS and proton conducting mesoporous SO3H-Si-MCM-41 nanoparticles for improved proton sensitivity. The composite gate electrode doubles the proton sensitivity of the OTFT, indicating a clear advantage of adding SO3H-Si-MCM-41 in the PEDOT:PSS gate. Moreover, the OTFTs with the composite gate electrode maintained OTFT characteristics similar to that of the PEDOT:PSS gated OTFT. A detailed and systematic study of the effect of variation in the composition of PEDOT:PSS:SO3H-Si-MCM-41 on OTFT characteristics and sensing properties is carried out. Our results open up the possibility of combining inorganic nanomaterials with organic conductors in the development of highly efficient bioelectronic sensing platforms.

КОНТРОЛЬ І МОДЕЛЮВАННЯ ПАРАМЕТРІВ ДЛЯ ТЕПЛОВОЇ ДІАГНОСТИКИ ПОРУШЕНЬ СИЛОВОГО ЕЛЕКТРООБЛАДНАННЯ

It has been considered the heat processes of traction electric engines parts in the maintenance and possible ways of heat generation modeling, which intensity is interconnected with operating physical quantities and possible components failure of traction electric drives in urban electric transport. The reasonable choice of input parameters, which control is possible with the help of remote techniques, located outside the mobile vehicle, was used in the development of pilot plant. By means of experimental equipment set containing electromechanical device in the form of a traction drive and brake, means for setting, regulation and control of technological input values and experimental device for measuring heating temperature electric engine with a given accuracy, it was realized the prepared experiment plan, implemented the variation of thermal processes in possible duty cycles of traction power equipment occurring on real urban routes. By means of differential electronic transducer “temperature-frequency” (T–F), the results of changing output ordinate were recorded and used in polynomial modeling of heating process in electric engine. The regression second order model, describing the thermal process, a spectral analyzer for record and visual control of output ordinate, were used for studying heat generation in laboratory-like environments and for evaluating the possibility of using standard and experimental control device for real traction substations of urban electric transport during remote technical diagnostics equipment according to its heating temperature. Using experimental differential electronic transducer T–F with a modulator and short mathematical description of heating process of traction electric drive allow to identify thermal processes with using of computing tools, which are different in few resources. It has been considered hardware-based ways to achieve the desired measuring set accuracy of the output ordinate and a program solution variant of the spectral low-frequency signal analyzer, which realization is possible by means of popular microcontrollers. The results have confirmed the appropriateness of studying thermal processes in electrical equipment and devices for synthesis of local compact remote equipment, which allows to create technical diagnostics devices and neural networks for possible failures evaluation, determined by the heat gradient in parts of power equipment of urban electric vehicles, operated on various routes and in different conditions.

A machine vision platform for measuring imbibition of maize kernels: quantification of genetic effects and correlations with germination

BackgroundImbibition (uptake of water by a dry seed) initiates the germination process. An automated method for quantifying imbibition would enable research on the genetic elements that influence the underlying hydraulic and biochemical processes. In the case of crop research, a high throughput imbibition assay could be used to investigate seed quality topics or to improve yield by selecting varieties with superior germination characteristics.ResultsAn electronic force transducer measured imbibition of single maize kernels with very high resolution but low throughput. An image analysis method was devised to achieve high throughput and sufficient resolution. A transparent fixture held 90 maize kernels in contact with water on the imaging window of a flatbed document scanner that produced an image of the kernels automatically every 10 min for 22 h. Custom image analysis software measured the area A of each indexed kernel in each image to produce imbibition time courses. The ultimate change in area (ΔA) ranged from 19.3 to 23.4% in a population of 72 hybrids derived from 9 inbred parents. Kernel area as a function of time was fit well by Aleft( t right) = A_{f} left( {1 - e^{ - kt} } right) where Af is the final kernel area. The swelling coefficient, k, ranged from 0.098 to 0.159 h−1 across the genotypes. The full diallel structure of the population enabled maternal genotype effects to be assessed. In a separate experiment, measurements of kernels of the same 25 inbreds produced in three different years demonstrated that production and storage variables affected imbibition much less than genotype. In a third experiment, measurements of 30 diverse inbred lines showed that k varied inversely with germination time (r = − 0.7) and directly with germination percentage (r = 0.7).ConclusionsNonspecialized imaging hardware and custom analysis software running on public cyber infrastructure form a low-cost platform for measuring seed imbibition with high resolution and throughput. We measured imbibition of thousands of kernels to determine that genotype influenced imbibition of maize kernels much more than seed production and storage environments. In some hybrids, k depended on which inbred parent was maternal. Quantitative relationships between k and germination traits were discovered.

Characteristics of the cerebrospinal fluid pressure waveform and craniospinal compliance in idiopathic intracranial hypertension subjects

BackgroundIdiopathic intracranial hypertension (IIH) is a condition of abnormally high intracranial pressure with an unknown etiology. The objective of this study is to characterize craniospinal compliance and measure the cerebrospinal fluid (CSF) pressure waveform as CSF is passively drained during a diagnostic and therapeutic lumbar puncture (LP) in IIH.MethodsEighteen subjects who met the Modified Dandy Criteria, including papilledema and visual field loss, received an ultrasound guided LP where CSF pressure (CSFP) was recorded at each increment of CSF removal. Joinpoint regression models were used to calculate compliance from CSF pressure and the corresponding volume removed at each increment for each subject. Twelve subjects had their CSFP waveform recorded with an electronic transducer. Body mass index, mean CSFP, and cerebral perfusion pressure (CPP) were also calculated. T-tests were used to compare measurements, and correlations were performed between parameters.ResultsCerebrospinal fluid pressure, CSFP pulse amplitude (CPA), and CPP were found to be significantly different (p < 0.05) before and after the LP. CSFP and CPA decreased after the LP, while CPP increased. The craniospinal compliance significantly increased (p < 0.05) post-LP. CPA and CSFP were significantly positively correlated.ConclusionsBoth low craniospinal compliance (at high CSFP) and high craniospinal compliance (at low CSFP) regions were determined. The CSFP waveform morphology in IIH was characterized and CPA was found to be positively correlated to the magnitude of CSFP. Future studies will investigate how craniospinal compliance may correlate to symptoms and/or response to therapy in IIH subjects.

Ultra-thin bimetallic alloy nanowires with porous architecture/monolayer MoS2 nanosheet as a highly sensitive platform for the electrochemical assay of hazardous omethoate pollutant

A novel electrochemical biosensor was designed for sensitive detection of organophosphate pesticides based on three-dimensional porous bimetallic alloy architecture with ultrathin nanowires (PdCo NWs, PdCu NWs, PdNi NWs) and monolayer MoS2 nanosheet (m-MoS2). The bimetallic alloy NWs/m-MoS2 nanomaterials were used as a sensing platform for electrochemical analysis of omethoate, a representative organophosphate pesticide, via acetylcholinesterase inhibition pathway. We demonstrated that all three bimetallic alloy NWs enhanced electrochemical responses of enzymatic biosensor, benefited from bimetallic synergistic action and porous structure. In particular, PdNi NWs outperformed other two bimetallic alloy. Moreover, PdNi NWs/m-MoS2 as an electronic transducer is superior to the corresponding biosensor in the absence of monolayer MoS2 nanosheet, which arise from synergistic signal amplification effect between different components. Under optimized conditions, the developed biosensor on the basis of PdNi NWs/m-MoS2 shows outstanding performance for the electrochemical assay of omethoate, such as a wide linear range (10−13 M∼10-7 M), a low detection limit of 0.05 pM at a signal-to-noise ratio of 3, high sensitivity and long-time stability. The results demonstrate that bimetallic alloy NWs/m-MoS2 nanocomposites could be excellent transducers to promote electron transfer for the electrochemical reactions, holding great potentials in the construction of current and future biosensing devices.

Exploiting interfacial phenomena in organic bioelectronics: Conformable devices for bidirectional communication with living systems.

A novel fully organic bioelectronic device is presented and validated as electronic transducer and current stimulator for brain implants. The device integrates polymeric electrodes made of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) on paper thin foils, resulting in a high surface-to-volume ratio architecture that exhibits high sensitivity to interfacial ionic transport phenomena. The prototyping technique herein presented yields devices for the bidirectional communication with biological systems whose dimensionality can be controlled according to the desired application. Transduction of ultra-low local-field potentials and delivery of voltage pulse-trains alike those used in deep-brain stimulation are herein assessed, paving the way towards novel theranostic strategies for the treatment of Parkinson's Disease and other severe neurodegenerative and/or traumatic pathologies of the central nervous system.

High-performance piezoelectric (K,Na,Li)(Nb,Ta,Sb)O3 single crystals by oxygen annealing

Ferroelectric single crystals exhibit the largest known piezoelectric constants and therefore show high potential for application in electronic devices, including sensors, actuators, and transducers. Their large properties, however, can only be fully exploited if the behavior is not influenced by lattice defects, formed during high-temperature processing. Such defects can inhibit domain-wall movement, increase leakage currents, and are predominantly responsible for the poor performance of the emerging ferroelectric crystals. Here, an approach to considerably enhance the piezoelectric and ferroelectric properties of (K,Na,Li)(Nb,Ta,Sb)O3 crystals by oxygen annealing is investigated. As compared to the non-annealed crystals, polarization, strain, and piezoelectric constant of the annealed sample were enhanced by a factor of two, resulting in an outstanding room-temperature value of piezoelectric constant d33 = 732 pC/N and a peak value of d33 = 1431 pm/V at the orthorhombic-tetragonal transition. The behavior was analyzed using electromechanical measurements, Mössbauer spectroscopy, and impedance spectroscopy, revealing decreased concentrations of both oxygen vacancies and Sb3+ ions after annealing. The findings indicate that the control of the defect chemistry enables these ferroelectric (K,Na)NbO3-based single crystals to outperform their polycrystalline counterparts and reach the values of lead-containing compositions. Moreover, the present strategy enables further detailed studies of the inherent crystal anisotropy and the possibilities for domain engineering.

Micro-patterned graphene-based sensing skins for human physiological monitoring

Ultrathin, flexible, conformal, and skin-like electronic transducers are emerging as promising candidates for noninvasive and nonintrusive human health monitoring. In this work, a wearable sensing membrane is developed by patterning a graphene-based solution onto ultrathin medical tape, which can then be attached to the skin for monitoring human physiological parameters and physical activity. Here, the sensor is validated for monitoring finger bending/movements and for recognizing hand motion patterns, thereby demonstrating its future potential for evaluating athletic performance, physical therapy, and designing next-generation human-machine interfaces. Furthermore, this study also quantifies the sensor’s ability to monitor eye blinking and radial pulse in real-time, which can find broader applications for the healthcare sector. Overall, the printed graphene-based sensing skin is highly conformable, flexible, lightweight, nonintrusive, mechanically robust, and is characterized by high strain sensitivity.

EFFECT OF MOUTAIN BIKE SPIRGRIPS® ON TRANSMISSIBILITY OF MECHANICAL VIBRATIONS, PERCEIVED COMFORT, MUSCULAR ACTIVITY AND HAND GRIP FORCE

Background: Prolonged mountain biking can involve pain complain in the wrists due to the ulnar nerve compression when using traditional grips (Capitani et al., 2002; Eckman et al., 1975). This phenomenon seems to be amplified by mechanical vibrations that are largely encountered during MTB practice despite the use of damping systems located in the fork and/or the frame. Recently, SPIRGRIPS® (SG) have been designed to correct the position of the hands of the user naturally by aligning the joints of his forearms correctly which is not the case with traditional grips. Purpose: The aim of this experimental study was to evaluate the effect of SG on transmissibility of mechanical vibrations, perceived comfort, muscular activity and hand grip force during a prolonged pedalling exercise. Methods: Sixteen trained cyclists without SG experience (age: 27 ± 10 years; height: 178 ± 6 cm; mass: 70 ± 7 kg) volunteered to participate in the study. Each participant performed a one-day laboratory cycling test on an aluminium hardtail mountain bike (Merida, Taiwan, Taiwan) equipped with a wireless SRM crank powermeter (Schoberer Rad Messtechnik, Fuchsend, Germany; accuracy ± 1%). The rear wheel of the bike was fixed onto an electromagnetic-braked ergometer (Elite, Fontaniva, Italy) while the front fork of the bike was connected to an electrical motor by a mechanical pivot. The test included two 20-minutes pedalling sessions at ~200 W that were separated by 20-minutes of passive recovery. Each pedalling session contained two pedalling periods of 9 minutes with fork vibrations interspersed by 2 min of pedalling without fork vibrations. Mechanical vibrations delivered by the motor were characterized by vertical acceleration from 12 to 53 m.s -2 and vibration frequency from 4 to 17 Hz. Participants had to keep their hands on the traditional grips (TG) or on the ergonomic SG throughout the pedalling session. All the subjects reported their ratings of perceived comfort (RPC) on a visual numeric scale graded from 0 (very much uncomfortable) to 10 (very much comfortable) approximately 10 seconds before the end of pedalling bout. Mechanical vibrations were simultaneously measured at 1350 Hz on the mechanical pivot of the ergometer and the right wrist of the rider by two Hikob Fox inertial measurement units (HIKOB, Vileurbanne, France). Surface EMG activity of flexor carpi radialis (FCR), extensor digitorum (ED) and triceps brachii (TB) were continuously measured by Trigno sensors (Delsys, Boston, USA) which are composed of two dry bar electrodes (1 mm x 10 mm) spaced by 10 mm. Maximum voluntary grip force (MVGF) of right hand was measured by an electronic force transducer one minute before and one minute after each pedalling session. Statistical analysis was assessed by paired t-test (MVGF) and two way (grips x vibration frequency) repeated measured ANOVA (RMS of EMG and vertical acceleration data) by Statistica (Statsoft, Tulsa, USA). Results: While MVGF decreased by 7% after pedalling exercise with TG (p < 0.05), no significant change in MVGF was found with SG. Transmissibility of vertical acceleration to the wrist was higher with SG when vibration frequency exceeds 8 Hz (Figure 2), but the difference with the TG was only significant at 17 Hz. EMG activity of FCR and TB muscles was lower with SG, notably for the highest vibration frequencies (12 and 14 Hz). RPC was not significantly different between the two grips whatever the vibration frequency.  Conclusion: This study showed that the use of MTB SPIRGRIPS® decreases fingers flexor and elbow extensor muscle activity while increasing vibration transmissibility to the wrist. In addition, maximum voluntary grip force was not altered after a prolonged pedalling exercise with vibrations. Therefore, these ergonomic grips would be interesting for mountain bikers to keep force reserve in hand and forearm for braking in steeper downhill and/or driving bike in technical sections. Acknowledgment : The authors would like to thank Pascal Badollet founder of SPIRGRIPS®, for his technical helpful.