Inertia Coupling Analysis of a Self-Decoupled Wheel Force Transducer under Multi-Axis Acceleration Fields

Wheel force transducer (WFT), which measures the three-axis forces and three-axis torques applied to the wheel, is an important instrument in the vehicle testing field and has been extremely promoted by researchers with great interests. The transducer, however, is typically mounted on the wheel of a moving vehicle, especially on a high speed car, when abruptly accelerating or braking, the mass/inertia of the transducer/wheel itself will have an extra effect on the sensor response so that the inertia/mass loads will also be detected and coupled into the signal outputs. The effect which is considered to be inertia coupling problem will decrease the sensor accuracy. In this paper, the inertia coupling of a universal WFT under multi-axis accelerations is investigated. According to the self-decoupling approach of the WFT, inertia load distribution is solved based on the principle of equivalent mass and rotary inertia, thus then inertia impact can be identified with the theoretical derivation. The verification is achieved by FEM simulation and experimental tests. Results show that strains in simulation agree well with the theoretical derivation. The relationship between the applied acceleration and inertia load for both wheel force and moment is the approximate linear, respectively. All the relative errors are less than 5% which are within acceptable and the inertia loads have the maximum impact on the signal output about 1.5% in the measurement range.     

Passive wireless MEMS microphones for biomedical applications

This paper introduces passive wireless telemetry based operation for high frequency acoustic sensors. The focus is on the development, fabrication, and evaluation of wireless, battery-less SAW-IDT MEMS microphones for biomedical applications. Due to the absence of batteries, the developed sensors are small and as a result of the batch manufacturing strategy are inexpensive which enables their utilization as disposable sensors. A pulse modulated surface acoustic wave interdigital transducer (SAW-IDT) based sensing strategy has been formulated. The sensing strategy relies on detecting the ac component of the acoustic pressure signal only and does not require calibration. The proposed sensing strategy has been successfully implemented on an in-house fabricated SAW-IDT sensor and a variable capacitor which mimics the impedance change of a capacitive microphone. Wireless telemetry distances of up to 5 centimeters have been achieved. A silicon MEMS microphone which will be used with the SAW-IDT device is being microfabricated and tested. The complete passive wireless sensor package will include the MEMS microphone wire-bonded on the SAW substrate and interrogated through an on-board antenna. This work on acoustic sensors breaks new ground by introducing high frequency (i.e., audio frequencies) sensor measurement utilizing SAW-IDT sensors. The developed sensors can be used for wireless monitoring of body sounds in a number of different applications, including monitoring breathing sounds in apnea patients, monitoring chest sounds after cardiac surgery, and for feedback sensing in compression (HFCC) vests used for respiratory ventilation. Another promising application is monitoring chest sounds in neonatal care units where the miniature sensors will minimize discomfort for the newborns.     

Insertional protein engineering for analytical molecular sensing

The quantitative detection of low analyte concentrations in complex samples is becoming an urgent need in biomedical, food and environmental fields. Biosensors, being hybrid devices composed by a biological receptor and a signal transducer, represent valuable alternatives to non biological analytical instruments because of the high specificity of the biomolecular recognition. The vast range of existing protein ligands enable those macromolecules to be used as efficient receptors to cover a diversity of applications. In addition, appropriate protein engineering approaches enable further improvement of the receptor functioning such as enhancing affinity or specificity in the ligand binding. Recently, several protein-only sensors are being developed, in which either both the receptor and signal transducer are parts of the same protein, or that use the whole cell where the protein is produced as transducer. In both cases, as no further chemical coupling is required, the production process is very convenient. However, protein platforms, being rather rigid, restrict the proper signal transduction that necessarily occurs through ligand-induced conformational changes. In this context, insertional protein engineering offers the possibility to develop new devices, efficiently responding to ligand interaction by dramatic conformational changes, in which the specificity and magnitude of the sensing response can be adjusted up to a convenient level for specific analyte species. In this report we will discuss the major engineering approaches taken for the designing of such instruments as well as the relevant examples of resulting protein-only biosensors.     

Biosensors

Biosensors are analytical devices that respond selectively to analytes in an appropriate sample and convert their concentration into an electrical signal via a combination of a biological recognition system and an electrochemical, optical or other transducer. Such devices will find application in medicine, agriculture, environmental monitoring and the bioprocessing industries. The last few years have seen great advances in the design of sensor architectures, the marriage of biological systems with monolithic silicon and optical technologies, the development of effective electron-transfer systems and the configuration of direct immunosensors. Recent progress in these areas has already led to the introduction of new-generation biosensors into the competitive diagnostics market place.     

Biosensors

Two decades of research into biosensors has been accelerated recently by the commercial potential offered by biotechnology. New developments in biosensor technology in which a biologically sensitive material is immobilized in intimate contact with a suitable potentiometric, amperometric, optical or other transducer are described. It is expected that some of these devices will be commercialized in 1984.     

Potential impacts from the release of transgenic plants into the environment

Transformation techniques are making it possible to produce novel and unusual plant phenotypes. When considering the environmental impact of these, it is important to do so in the context of what is known about conventional plant breeding and the thousands of varieties that have been produced during this century and earlier. There has now been over ten years of experience of environmental impact assessment with transgenic plants, and research has enabled that assessment process to be better informed scientifically. There are, however, important challenges for the future. Fundamental changes in plant biology, including enhanced tolerance to stressful environments, may create a class of plants that are different from those that have been produced so far, and there may be lessons to be learnt from the experience worldwide of the release of exotic species into different countries. Scale-dependent effects of transgenic plants in agriculture can only effectively be measured by large scale production and monitoring. The monitoring process presents a number of challenges to provide oversight that is meaningful and helpful in assessing environmental impact. The international transboundary movement of transgenic plants is already a reality, and it is important that our environmental impact assessments take this possibility into account. This includes both intentional transboundary movement, through trade of commodity crops, but also unintentional transboundary movement, including the possibility of seeds being moved by animals, by transportation and by humans across the world. There are some major challenges in devising agricultural strategies for the transgenic crops that will become available in the future. The responsibility for developing agricultural strategy rests at a number of levels. To achieve this, it will be necessary to have effective dialogue between the regulatory authorities, the plant breeding and agrochemical industries, and the farming industry. There are already encouraging moves in this direction and hopefully this will continue.     

A theory for analysis of cell populations with non-cycling S phase cells

Analyses of cell populations that have been labeled in vivo with analogs of thymidine that are incorporated by cells synthesizing DNA and then monitored over time by bivariate flow cytometry sometimes detect populations of cells that have S phase DNA content but that have not acquired label. Two alternative explanations for the lack of labeling are that either the cells were not exposed to the label or that the cells stopped DNA synthesis and ceased progression through S phase. To help determine which scenario is the more likely, a model has been devised for studying a population of cells that includes the possibility that cells in S phase will cease DNA synthesis. In this model, the initial fraction of unlabeled cells in S phase depends on two rates: the growth rate of the total population and the number of cells that cease progression through S phase per unit time. The model is used to analyze the changing quantities which can be measured by monitoring the population of cells over time and is used to estimate the two rates required to compute the initial fraction of unlabeled S phase cells. Thus, the initial fraction of unlabeled cells can be compared with that predicted by the population dynamics to determine whether one explanation for the failure of some cells to be labeled is preferable to the other, which in turn might offer information about tumor microvascular or cytologic properties.     

Transducer for monitoring respiration during imaging procedures

A transducer system for monitoring respiration is described; it uses a ‘liquid column’ sensor with a remote integrated circuit pressure module. It was designed primarily for non-invasive monitoring and control of respiration during diagnostic imaging procedures, but has also found applications in other areas, e.g. physiotherapy and pulse monitoring. The device is a new version of a system developed several years ago and takes advantage of relatively low cost commercial ‘building blocks’. The output is an analogue voltage (from a low impedance source) capable of driving a wide range of recorders, amplifiers and computer interfaces. Reference is also made in the text to a bio-feedback signal processing and display unit (described elsewhere) which, when used with this transducer, provides a versatile respiratory control system.     

Determination of Fc function with frozen red blood cells.

The Fc function of immunoglobulins is commonly determined by an assay based on monitoring immunoglobulin induced, complement mediated red cell lysis. This assay requires a continuous source of fresh red cells. We have shown that the assay can be successfully performed with frozen red cells. The possibility of access to a stored standard stock of red cells will improve the convenience of performing the assay and could contribute to improved assay reproducibility.     

Four Theorems on the Psychometric Function

In a 2-alternative forced-choice (2AFC) discrimination task, observers choose which of two stimuli has the higher value. The psychometric function for this task gives the probability of a correct response for a given stimulus difference, . This paper proves four theorems about the psychometric function. Assuming the observer applies a transducer and adds noise, Theorem 1 derives a convenient general expression for the psychometric function. Discrimination data are often fitted with a Weibull function. Theorem 2 proves that the Weibull “slope” parameter, , can be approximated by , where is the of the Weibull function that fits best to the cumulative noise distribution, and depends on the transducer. We derive general expressions for and , from which we derive expressions for specific cases. One case that follows naturally from our general analysis is Pelli''s finding that, when , . We also consider two limiting cases. Theorem 3 proves that, as sensitivity improves, 2AFC performance will usually approach that for a linear transducer, whatever the actual transducer; we show that this does not apply at signal levels where the transducer gradient is zero, which explains why it does not apply to contrast detection. Theorem 4 proves that, when the exponent of a power-function transducer approaches zero, 2AFC performance approaches that of a logarithmic transducer. We show that the power-function exponents of 0.4–0.5 fitted to suprathreshold contrast discrimination data are close enough to zero for the fitted psychometric function to be practically indistinguishable from that of a log transducer. Finally, Weibull reflects the shape of the noise distribution, and we used our results to assess the recent claim that internal noise has higher kurtosis than a Gaussian. Our analysis of for contrast discrimination suggests that, if internal noise is stimulus-independent, it has lower kurtosis than a Gaussian.     

Taurine and Its Chloramine: Modulators of Immunity

Taurine is a semiessential amino acid that is not incorporated into proteins. In mammalian tissues, taurine is ubiquitous and is the most abundant free amino acid in the heart, retina, skeletal muscle, and leukocytes. Taurine reaches up to 50 mM concentration in leukocytes. Taurine has been shown to be tissue-protective in many models of oxidant-induced injury. One possibility is that taurine reacts with HOCl, produced by the myeloperoxidase (MPO) pathway, to produce the more stable but less toxic taurine chloramine (Tau-Cl). However, data from several laboratories demonstrate that Tau-Cl is a powerful regulator of the immune system. Specifically, Tau-Cl has been shown to downregulate the production of proinflammatory mediators in both rodent and human leukocytes. Recent molecular studies on the function of taurine provide evidence that taurine is a constituent of biological macromolecules. Specifically, two novel taurine-containing modified uridines have been found in both human and bovine mitrochondria. In studies on mechanism of action, Tau-Cl inhibits the activation of NFkappaB, a potent signal transducer for inflammatory cytokines, by oxidation of IkappaB alpha at methionine45. Taurine transporter knockout mice show reduced taurine, reduced fertility, and loss of vision resulting from severe retinal degeneration, which was found to be due to apoptosis. Apoptosis induced by amino chloramines is a current and important finding because oxidants derived from leukocytes play a key role in killing pathogens. The fundamental importance of taurine in adaptive and acquired immunity will be revealed using genetic manipulation.     

Bioelectronic nose and its application to smell visualization

There have been many trials to visualize smell using various techniques in order to objectively express the smell because information obtained from the sense of smell in human is very subjective. So far, well-trained experts such as a perfumer, complex and large-scale equipment such as GC-MS, and an electronic nose have played major roles in objectively detecting and recognizing odors. Recently, an optoelectronic nose was developed to achieve this purpose, but some limitations regarding the sensitivity and the number of smells that can be visualized still persist. Since the elucidation of the olfactory mechanism, numerous researches have been accomplished for the development of a sensing device by mimicking human olfactory system. Engineered olfactory cells were constructed to mimic the human olfactory system, and the use of engineered olfactory cells for smell visualization has been attempted with the use of various methods such as calcium imaging, CRE reporter assay, BRET, and membrane potential assay; however, it is not easy to consistently control the condition of cells and it is impossible to detect low odorant concentration. Recently, the bioelectronic nose was developed, and much improved along with the improvement of nano-biotechnology. The bioelectronic nose consists of the following two parts: primary transducer and secondary transducer. Biological materials as a primary transducer improved the selectivity of the sensor, and nanomaterials as a secondary transducer increased the sensitivity. Especially, the bioelectronic noses using various nanomaterials combined with human olfactory receptors or nanovesicles derived from engineered olfactory cells have a potential which can detect almost all of the smells recognized by human because an engineered olfactory cell might be able to express any human olfactory receptor as well as can mimic human olfactory system. Therefore, bioelectronic nose will be a potent tool for smell visualization, but only if two technologies are completed. First, a multi-channel array-sensing system has to be applied for the integration of all of the olfactory receptors into a single chip for mimicking the performance of human nose. Second, the processing technique of the multi-channel system signals should be simultaneously established with the conversion of the signals to visual images. With the use of this latest sensing technology, the realization of a proper smell-visualization technology is expected in the near future.     

Biosensor technology: technology push versus market pull

Biosensor technology is based on a specific biological recognition element in combination with a transducer for signal processing. Since its inception, biosensors have been expected to play a significant analytical role in medicine, agriculture, food safety, homeland security, environmental and industrial monitoring. However, the commercialization of biosensor technology has significantly lagged behind the research output as reflected by a plethora of publications and patenting activities. The rationale behind the slow and limited technology transfer could be attributed to cost considerations and some key technical barriers. Analytical chemistry has changed considerably, driven by automation, miniaturization, and system integration with high throughput for multiple tasks. Such requirements pose a great challenge in biosensor technology which is often designed to detect one single or a few target analytes. Successful biosensors must be versatile to support interchangeable biorecognition elements, and in addition miniaturization must be feasible to allow automation for parallel sensing with ease of operation at a competitive cost. A significant upfront investment in research and development is a prerequisite in the commercialization of biosensors. The progress in such endeavors is incremental with limited success, thus, the market entry for a new venture is very difficult unless a niche product can be developed with a considerable market volume.     

Computer cardiokymography. On its way to long-term noninvasive monitoring of cardiac performance in daly life

A functioning heart generates low-frequency and low-amplitude movements (up to 40 (mrn) of soft tissues in the percardial area. Since the 1950-s of the XX-th century cardiologists have studied these movements to employ them in the diagnostics of ischemic heart disease (IHD). Indeed, changes of the movements have found their diagnostic application in this field. If blood supply to a certain area of ventricular myocardium is insufficient the contractions in this area diminish and even ceases. After systolic increase in ventricular pressure this area dilates and forces intercostal tissues out, causing a "bulge" wave on the record. For recording the patient must be in supine position and hold the breath. High frequency electromagnetic field generator was used in an attempt to examine the heart movements. It was found that such instrument measures the thickness of the air-gap that serves as a dielectric or a "capacitor" which forms between the skin and approaching it flat inductive coil. Nevertheless, such an instrument (cardiokymograph, CKG) can reveal changes in contractions of ischemic myocardium and markedly increases the sensitivity of the exercise ECG test. However, CKG can be recorded only after termination of the test. This principal disadvantage has been overcome by software that allowed the recording of CKG during the test. A low-frequency capacitance transducer developed recently by Chinese researchers has provided a simultaneous recording of several CKG. After modifying the transducer, we have established that 1) the shape of CKGs is the same as that CKGs recorded by all our predecessors, 2) CKGs are reproducible even within a 3-month interval, 3) the enormous mechanical interference caused by respiratory movements and, to a greater extent, by the vigorous movements of the legs and trunk during veloergometry can be eliminated by digital processing of the transducer signals, and 4) pathological changes appear in CKG of patients with IHD, which enables one to stop veloergometry at lower loads, thus increasing the safety of the test. Since for large medical insurance companies very simple and inexpensive cardiokymograph are quite unprofitable, their commercially production in USA and in Germany has been stopped. However, the goal of cardiokymography: a real-time, beat-to-beat, long-term monitoring of cardiac function in daily life, remains the major factor determining the future of the method.     

Piezoelectric biosensors: strategies for coupling nucleic acids to piezoelectric devices

The development of a piezoelectric biosensor based on nucleic acids interaction is presented focusing on the methodology for probe immobilization. This is a key step in any DNA biosensor development. Often, the detection limits and, in general, the analytical performances of the biosensor can be improved by optimizing the immobilization of the receptor on the transducer surface. DNA must be attached to the solid support, retaining native conformation, and binding activity. This attachment must be stable over the course of a binding assay and, in addition, sufficient binding sites must be presented to the solution phase to interact with the analyte. In this paper, the optimization of the coating of the gold quartz crystal surface, to immobilize an oligonucleotide probe, is reported. Two immobilization procedures are illustrated in details with a comparison regarding the immobilization of the probe, the detection of the hybridization reaction, and the possibility of regeneration. The two procedures are based on the use of biotinylated or thiolated DNA probes. Specific applications will be also presented.     

Transducers,sensors, and instrumentation in clinical biomechanics

Successful measurements in any field are dependent on the availability of appropriate transducer materials and the associated instrumentation. In recent years there has been a most welcome advance in both these areas. If we consider first the transducer developments that have recently taken place, these have much to do with the discovery and application of new materials such as electroactive polymers, fibre optic devices and many others. Instrumentation has largely benefitted from the microelectronics revolution. Our ability to process and ultimately display data has improved to a remarkable extent. Indeed, the designer of instrumentation is under enormous pressure to convert the data into the digital domain as early as possible simply because the resulting instrument will usually be easier to design and construct, more accurate, more reliable, smaller and possibly more important still, cheaper. This paper reviews some of these developments, gives a number of examples of applications in the clinical biomechanics area and makes some predictions for future developments.     

Pharmacogenetic testing, informed consent and the problem of secondary information

Numerous benefits for patients have been predicted if prescribing decisions were routinely accompanied by pharmacogenetic testing. So far, little attention has been paid to the possibility that the routine application of this new technology could result in considerable harm to patients. This article emphasises that pharmacogenetic testing shares both the opportunities and the pitfalls with 'conventional' disease-genetic testing. It demonstrates that performing pharmacogenetic tests as well as interpreting the results are extraordinarily complex issues requiring a high level of expertise. It further argues that pharmacogenetic testing can have a huge impact on clinical decisions and may influence the therapeutic strategy as well as the clinical monitoring of a patient. This view challenges the predominant paradigm that pharmacogenetic testing will predict patients' responses to medicines, but that it will not provide any other significant disease-specific predictive information about the patient or family members. The article also questions published proposals to reduce the consent procedure for pharmacogenetic testing to a simple statement that the physician wishes to test a sample of the patient's DNA to see if a drug will be safe or whether it will work, and presents an alternative model that is better suited to protect patient's interests and to obtain meaningful informed consent. The paper concludes by outlining conditions for the application of pharmacogenetic testing in clinical practice in a way that can make full use of its potential benefits while minimising possible harm to patients and their families.