Single-channel Devices Research Articles

Quality Assessment of Single-Channel EEG for Wearable Devices.

The recent embedding of electroencephalographic (EEG) electrodes in wearable devices raises the problem of the quality of the data recorded in such uncontrolled environments. These recordings are often obtained with dry single-channel EEG devices, and may be contaminated by many sources of noise which can compromise the detection and characterization of the brain state studied. In this paper, we propose a classification-based approach to effectively quantify artefact contamination in EEG segments, and discriminate muscular artefacts. The performance of our method were assessed on different databases containing either artificially contaminated or real artefacts recorded with different type of sensors, including wet and dry EEG electrodes. Furthermore, the quality of unlabelled databases was evaluated. For all the studied databases, the proposed method is able to rapidly assess the quality of the EEG signals with an accuracy higher than 90%. The obtained performance suggests that our approach provide an efficient, fast and automated quality assessment of EEG signals from low-cost wearable devices typically composed of a dry single EEG channel.

Multi-channel tri-gate normally-on/off AlGaN/GaN MOSHEMTs on Si substrate with high breakdown voltage and low ON-resistance

In this work, we present multi-channel tri-gate AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOSHEMTs) for high-voltage applications. A heterostructure with multiple AlGaN/GaN layers was used to form five parallel two-dimensional-electron-gas (2DEG) channels to reduce the ON-resistance (RON), simultaneously modulated by the 3-dimensional tri-gate electrodes. The tri-gate is a unique technology to control the multi-channels, providing enhanced electrostatics and device performance, and, in turn, the multi-channels are exceptionally suited to address the degradation in drain current (ID,max) caused by the tri-gate. With a tri-gate width (w) of 100 nm, normally-on multi-channel tri-gate transistors presented 3×-higher maximum drain current (ID,max), 47%-smaller RON, as well as 79%-higher maximum transconductance (gm,max), as compared to counterpart single-channel devices. Using the channel depletion through the tri-gate sidewalls, normally-off operation was also achieved by reducing w below the sidewall depletion width (wdep), resulting in a positive threshold voltage (VTH) of 0.82 V at 1 μA/mm. The devices presented a high breakdown voltage (VBR) of 715 V, which reveals a promising future platform for high-voltage low-RON GaN transistors.

Історія розвитку поліграфа в Україні: Науково-дослідний інженерний центр "Пульс" - перша в Україні наукова установа, яка займалася розробкою вітчизняних поліграфів у 2000-х роках

In July 2018, 10 years have passed since the liquidation of the first state scientific institution in Ukraine, which was professionally engaged in the development of domestic single-channel polygraphs for their mobile use in practical activities. Thus, by Resolution No. 320 of the Cabinet of Ministers of Ukraine dated May 5, 1995, the state institution "Research and Engineering Center "Pulse" was established in Ukraine, which was part of the Military Medical Department of the Security Service of Ukraine, with the class (type) of professional activity. Research and development in the field of natural and technical sciences" (KVED-2005: 73.10.0). Legal address: 01021, Kyiv, Pecherskyi district, Lypska street, 11. During 2001 - 2008, the Center was engaged in the development and implementation of registration devices emotional tension of a person - "lie detectors" of domestic production of the "Vector" series models - "Vector 01.1", "Vector 02.1", mock-up sample "Vector 14", as well as methodical support for scientific developments and introduction into professional activity of single-channel devices - "Vector 01.1 ", "Vector 02.1". Of the specified devices, the "Vector 14" model was produced in a single copy as an experimental, mock-up sample, which consisted of an open board of circuit elements and provided for the possibility of recording the research protocol and was supposed to become the first full-fledged Ukrainian multi-channel polygraph, however, in did not receive a connection with the suspended state funding for further development.

Monitoring driver fatigue using a single-channel electroencephalographic device: A validation study by gaze-based, driving performance, and subjective data

Driver fatigue can impair performance as much as alcohol does. It is the most important road safety concern, causing thousands of accidents and fatalities every year. Thanks to technological developments, wearable, single-channel EEG devices are now getting considerable attention as fatigue monitors, as they could help drivers to assess their own levels of fatigue and, therefore, prevent the deterioration of performance. However, the few studies that have used single-channel EEG devices to investigate the physiological effects of driver fatigue have had inconsistent results, and the question of whether we can monitor driver fatigue reliably with these EEG devices remains open. Here, we assessed the validity of a single-channel EEG device (TGAM-based chip) to monitor changes in mental state (from alertness to fatigue). Fifteen drivers performed a 2-h simulated driving task while we recorded, simultaneously, their prefrontal brain activity and saccadic velocity. We used saccadic velocity as the reference index of fatigue. We also collected subjective ratings of alertness and fatigue, as well as driving performance. We found that the power spectra of the delta EEG band showed an inverted U-shaped quadratic trend (EEG power spectra increased for the first hour and half, and decreased during the last thirty minutes), while the power spectra of the beta band linearly increased as the driving session progressed. Coherently, saccadic velocity linearly decreased and speeding time increased, suggesting a clear effect of fatigue. Subjective data corroborated these conclusions. Overall, our results suggest that the TGAM-based chip EEG device is able to detect changes in mental state while performing a complex and dynamic everyday task as driving.

All-optical regenerator of multi-channel signals

One of the main reasons why nonlinear-optical signal processing (regeneration, logic, etc.) has not yet become a practical alternative to electronic processing is that the all-optical elements with nonlinear input–output relationship have remained inherently single-channel devices (just like their electronic counterparts) and, hence, cannot fully utilise the parallel processing potential of optical fibres and amplifiers. The nonlinear input–output transfer function requires strong optical nonlinearity, e.g. self-phase modulation, which, for fundamental reasons, is always accompanied by cross-phase modulation and four-wave mixing. In processing multiple wavelength-division-multiplexing channels, large cross-phase modulation and four-wave mixing crosstalks among the channels destroy signal quality. Here we describe a solution to this problem: an optical signal processor employing a group-delay-managed nonlinear medium where strong self-phase modulation is achieved without such nonlinear crosstalk. We demonstrate, for the first time to our knowledge, simultaneous all-optical regeneration of up to 16 wavelength-division-multiplexing channels by one device. This multi-channel concept can be extended to other nonlinear-optical processing schemes.

Comparison of Single-Channel and Multi-Channel Cochlear Implants in Terms of Encoding Strategy and Speech Understanding: A Systematic Review

Introduction: The term channel in cochlear implant systems refers to the number of stimulation sites within the inner ear or cochlea that determines the range of frequencies or pitches. Unlike single-channel cochlear implant, a multi-channel cochlear implant system divides the incoming signal into various frequency bands, and then, transmits it to various stimulation areas within the inner ear. Having more stimulation sites entails two main goals: 1- As the auditory nerve fibers in the cochlea are tonotopically organized, higher number of electrodes leads to better frequency separation; 2- The areas in the cochlea with inappropriate or no response to electrical stimulation will be avoided in the programming of the device, and the components of the processed input frequency will accompany the stimulation. The goal of the present study was to compare the frequency encoding strategy and its effect on speech understanding of the recipients of single-channel and multi-channel cochlear implant systems. Materials and Methods: Published researches were identified by reviewing scientific databases (PubMed, Science Direct, and Google Scholar) from 1965 to 2016 using relevant keywords. The researches were selected based on the inclusion and exclusion criteria. Results: Single-channel cochlear implants encode the frequency based on the rate of firing of electrical impulses. Multi-channel cochlear implants ‎use the spatial strategy theory for frequency encoding, wherein the different frequencies of the auditory signal are separated and presented in a tonotopic manner along the length of the cochlea via the electrode array. The spatial and temporal encoding of the sound frequencies can be partly replicated by multi-channel stimulation of the auditory nerve. Encoding strategy in multi-channel cochlear implant consists of feature extraction and wave form. The resulting speech understanding of the single-channel and multi-channel systems was also assessed. Conclusion: Based on the findings, it can be concluded that single-channel cochlear implant systems with temporal encoding of frequency do not adequately convey speech information, whereas multi-channel cochlear implants ‎have more similarities to the tonotopic map of the cochlea and provide a better speech understanding in comparison to single channel devices.

Spontaneous jaw muscle activity in patients with acquired brain injuries—Preliminary findings

PatientsHigh or excessive parafunctional jaw muscle activity is a frequent complication of acquired brain injury (ABI) and may have some similarities to bruxism. Bruxism has been associated with increased tooth wear, masseter hypertrophy and headaches. The aim of this observational study was to identify the levels of jaw muscle activity from fourteen ABI patients having different functional and cognitive levels in their early phase of neurological rehabilitation (according to their Ranchos Los Amigos Scale (RLAS) score). Nine patients were severely cognitive impairement (RLAS score 1–3): with no or little response to any external stimuli due to low arousal and five patients were with RLAS score 4–8: depending on responses to stimuli and confusion level i.e. defining that patients had enough arousal to respond and react and therefore were able to follow the instructions. A single-channel electromyographic (EMG) device was used to assess the jaw muscle EMG activity in ABI patients for two hours continuously at two different days. DiscussionThe mean (±SD) jaw muscle activity observed in patients with ABI was 46.9±6.5 EMG events/h with a wide range between 1–163 EMG events/h but with no significant difference between days (P=0.230). ConclusionIrrespective of functional and cognitive ability scores patients with ABI had a wide range of EMG activity. The use of ambulatory single-channel EMG devices might open a path for further studies to determine levels of jaw muscle activity associated with potential side effects in ABI patients.

Cochlear Implantation

JOURNAL CLUB Cochlear Implantation: Asia–Pacific Symposium Is an Emerging Force By Fan-Gang Zeng, PhD; Shi-Ming Yang, MD, PhD; & Zhiqiang Gao, MD T he 10th Asia–Pacific Symposium on Cochlear Implants and Related Sciences (APSCI 2015) drew about 2,000 professionals to dis- cuss the latest research in Beijing from April 30 to May 3. The number of attendees was unprecedented, the weather cooperative, and the venue splendid, but the science was even better. One hot topic that consistently came up at the conference was how to narrow the re- maining gaps between prosthetic and normal hearing. Bruce J. Gantz, MD, of the University of Iowa designed special electrodes Blake S. Wilson, DSc, DEng, of Duke to produce a hybrid cochlear implant that preserves low-­frequency University reviewed the progress of co- acoustic hearing. chlear implant performance from essentially and 1,000 Hz needs to be preserved, preferably using the chance-level success with single-channel short (10-mm) electrodes while saving the long (16- or 20- devices in the 1980s to today’s multichannel devices that mm) electrodes for people who are older than 70 and have even allow most users to carry on cell phone conversations. more than 30 years of profound loss at high frequencies. He also noted a lack of improvement in unilateral cochlear Most surgeons also favored atraumatic insertion and struc- implant performance in the last two decades and suggested tural preservation in cochlear implantation, which are critical that improving unilateral performance serves as a “bedrock” to both short-term protection and long-term maintenance of critical to narrowing the gap between prosthetic and normal residual acoustic hearing. hearing. Using a biological approach in an animal model, Shi-Ming As a means to improve unilateral performance, Ingeborg Yang, MD, PhD, of Chinese People’s Liberation Army Gen- Hochmair, PhD, of MED-EL advocated the use of deep elec- eral Hospital in Beijing demonstrated that stem cells promote trodes to access low-frequency neurons while matching them auditory nerve growth toward the intra-cochlear electrodes, with appropriate temporal fine structure (Hear Res 2015; reducing power consumption while increasing spatial selec- tivity. For people with residual low-frequency acoustic hearing, This technique, similar to a gene-therapy approach (Sci Bruce J. Gantz, MD, of the University of Iowa designed spe- Transl Med 2014;6[233]:233ra54), may still be years away cial electrodes to produce a hybrid cochlear implant that pre- from human application, but it represents a promising future serves low-frequency acoustic hearing, augmenting and direction for enhancing the nerve–electrode interface and ul- enhancing the implant performance. timately the bionic ear performance. To achieve a hybrid hearing advantage, acoustic hearing better than 85 dB pure-tone average (PTA) between 125 Hz Dr. Zeng is chairman of The Hearing Journal Editorial Advisory Board, as well as director of the Center for Hearing Research and professor of anatomy and neurobiology, biomedical engineering, cognitive sciences, and otolaryngology at the University of Cali- fornia, Irvine. Dr. Yang is chairman of the Department of Otolaryngology–Head and Neck Surgery at the Chinese People’s Liberation Army Gen- eral Hospital in Beijing and copresident of the APSCI 2015 Scien- tific Committee. Dr. Gao is chairman of the Department of Otorhinolaryngology at Peking Union Medical College Hospital and the Chinese Acad- emy of Medical Sciences in Beijing, and copresident of the APSCI 2015 Scientific Committee. The Hearing Journal BINAURAL HEARING: SENSITIVE PERIOD Another major area covered at the conference was under- standing and utilizing brain plasticity in cochlear implanta- tion. Robert Briggs, MBBS, of the University of Melbourne re- viewed lessons learned from cochlear implant outcomes in children over the past 30 years, such as the younger the im- plant age, the better the outcome, particularly for children im- planted before their first birthday. Other significant factors are the child’s cognitive status and communication mode, with superior outcomes related to an oral versus a signing environment. A somewhat surprising finding was that children with bilateral implants have better July 2015

IMPLEMENTATION OF DETECTION STRUCTURE IN SINGLE-CHANNEL RADIO DEVICES OF THE NEAR RANGE

In article «Implementation of detection structure in single-channel radio devices of the near range» considered the devices used for the detection of objects in various control systems, defense and protection of open and closed areas. The purpose of the article is problems of estimating the parameters, enables us to justify the structure detection for wireless devices detec- tion. To solve the problem of object detection within a controlled area or space is determined by the value of the likelihood function. Analysis functions and likelihood ratios allows to create and optimize the structure of detection, to get maximum results in the reliability of the detection. Structure has been proposed for single-channel detection of radio sensors, based on the comparison of the correlation integrals arising from calculation of the likelihood ratio. In the structure of radio detection devices used two blocks production of the likelihood function. The results can be used to in a variety of electronic devices of the near range. So, based on the analysis of problems of detection and estimation of parameters in the electronic devices near range, to determine the influence functions and the likelihood ratio, consider the implementation structure of single-channel detection of radio sensors.

半正定値テンソル分解による瞬きアーチファクト除去手法の提案

In this paper, we aim to propose an eye blink artifact rejection technique for single-channel electroencephalographic (EEG) devices. Independent component analysis (ICA) is usually employed for eye blink artifact rejection. However, ICA cannot be used for the artifact rejection when we recorded EEG signals by single-channel EEG devices, since this method requires multichannel signals for source estimation. On the other hand, single-channel EEG devices have been attracted attention since 2000 because of its usability for measurement and portability. In this paper, we propose positive semi-definite tensor factorization (PSDTF) with 2 step learning method as a new eye blink artifact rejection technique for single-channel EEG analysis. We investigate its validity using signal-to-noise ratio (SNR) between eye blink artifact signals estimated by our proposed method or ICA. Average value of SNR across subjects and trials is 16.13dB. For the value, the validity of our proposed method for eye blink artifact rejection of single-channel EEG signals was confirmed.

Micro-channel plate photon detector studies for the TORCH detector

The Time Of internally Reflected Cherenkov light (TORCH) detector is under development. Charged particle tracks passing through a 1cm plate of quartz will generate the Cherenkov photons, and their arrival will be timed by an array of micro-channel plate photon detectors. As part of the TORCH R&D studies, commercial and custom-made micro-channel plate detectors are being characterized. The final photon detectors for this application are being produced in a three-phase program in collaboration with industry. Custom-made single-channel devices with extended lifetime have been manufactured and their performance is being systematically investigated in the laboratory. Optical studies for the preparation of beam and laboratory tests of a TORCH prototype are also underway.

Multiphysics simulation of ion concentration polarization induced by a surface-patterned nanoporous membrane in single channel devices.

Microfluidic devices utilize ion concentration polarization (ICP) phenomena for a variety of applications, but a comprehensive understanding of the generation of ICP is still necessary. Recently, the emergence of a novel single channel ICP (SC-ICP) device has stimulated further research on the mechanism of ICP generation, so that we developed a 2-D model of an SC-ICP device that integrates a nanoporous membrane on the bottom surface of the channel, allowing bulk flow over the membrane. We solved a set of coupled governing equations with appropriate boundary conditions to explore ICP numerically. As a result, we not only showed that the simulation results held a strong qualitative agreement with experimental results, but also found the distribution of ion concentrations in the SC-ICP device that has never been reported in previous studies. We confirmed again that the electrophoretic mobility (EPM) of counterions in the membrane is the most dominant factor determining the generation and strength of ICP, whereas the charge density of the membrane was dominant to the ICP strength only when a high EPM value was assumed. From the viewpoint of practical applications, an SC-ICP device with a long membrane under low buffer strength showed enhanced performance in the preconcentration of charged molecules. Therefore, we believe that the simulation results could not only provide sharp insight into ICP phenomena but also predict and optimize the performance of SC-ICP devices in various microfluidic applications.

High-performance ionic diode membrane for salinity gradient power generation.

Salinity difference between seawater and river water is a sustainable energy resource that catches eyes of the public and the investors in the background of energy crisis. To capture this energy, interdisciplinary efforts from chemistry, materials science, environmental science, and nanotechnology have been made to create efficient and economically viable energy conversion methods and materials. Beyond conventional membrane-based processes, technological breakthroughs in harvesting salinity gradient power from natural waters are expected to emerge from the novel fluidic transport phenomena on the nanoscale. A major challenge toward real-world applications is to extrapolate existing single-channel devices to macroscopic materials. Here, we report a membrane-scale nanofluidic device with asymmetric structure, chemical composition, and surface charge polarity, termed ionic diode membrane (IDM), for harvesting electric power from salinity gradient. The IDM comprises heterojunctions between mesoporous carbon (pore size ∼7 nm, negatively charged) and macroporous alumina (pore size ∼80 nm, positively charged). The meso-/macroporous membrane rectifies the ionic current with distinctly high ratio of ca. 450 and keeps on rectifying in high-concentration electrolytes, even in saturated solution. The selective and rectified ion transport furthermore sheds light on salinity-gradient power generation. By mixing artificial seawater and river water through the IDM, substantially high power density of up to 3.46 W/m(2) is discovered, which largely outperforms some commercial ion-exchange membranes. A theoretical model based on coupled Poisson and Nernst-Planck equations is established to quantitatively explain the experimental observations and get insights into the underlying mechanism. The macroscopic and asymmetric nanofluidic structure anticipates wide potentials for sustainable power generation, water purification, and desalination.

Automatic identification and removal of ocular artifacts in EEG--improved adaptive predictor filtering for portable applications.

Electroencephalogram (EEG) signals have a long history of use as a noninvasive approach to measure brain function. An essential component in EEG-based applications is the removal of Ocular Artifacts (OA) from the EEG signals. In this paper we propose a hybrid de-noising method combining Discrete Wavelet Transformation (DWT) and an Adaptive Predictor Filter (APF). A particularly novel feature of the proposed method is the use of the APF based on an adaptive autoregressive model for prediction of the waveform of signals in the ocular artifact zones. In our test, based on simulated data, the accuracy of noise removal in the proposed model was significantly increased when compared to existing methods including: Wavelet Packet Transform (WPT) and Independent Component Analysis (ICA), Discrete Wavelet Transform (DWT) and Adaptive Noise Cancellation (ANC). The results demonstrate that the proposed method achieved a lower mean square error and higher correlation between the original and corrected EEG. The proposed method has also been evaluated using data from calibration trials for the Online Predictive Tools for Intervention in Mental Illness (OPTIMI) project. The results of this evaluation indicate an improvement in performance in terms of the recovery of true EEG signals with EEG tracking and computational speed in the analysis. The proposed method is well suited to applications in portable environments where the constraints with respect to acceptable wearable sensor attachments usually dictate single channel devices.

Multi-channel PMMA microfluidic biosensor with integrated IDUAs for electrochemical detection.

A novel multi-channel poly(methyl methacrylate) (PMMA) microfluidic biosensor with interdigitated ultramicroelectrode arrays (IDUAs) for electrochemical detection was developed. The focus of the development was a simple fabrication procedure and the realization of a reliable large IDUA that can provide detection simultaneously to several microchannels. As proof of concept, five microchannels are positioned over a large single IDUA where the channels are parallel with the length of the electrode finger. The IDUAs were fabricated on the PMMA cover piece and bonded to a PMMA substrate containing the microfluidic channels using UV/ozone-assisted thermal bonding. Conditions of device fabrication were optimized realizing a rugged large IDUA within a bonded PMMA device. Gold adhesion to the PMMA, protective coatings, and pressure during bonding were optimized. Its electrochemical performance was studied using amperometric detection of potassium ferri and ferro hexacyanide. Cumulative signals within the same chip showed very good linearity over a range of 0-38 μM (R(2) = 0.98) and a limit of detection of 3.48 μM. The bonding of the device was optimized so that no cross talk between the channels was observed which otherwise would have resulted in unreliable electrochemical responses. The highly reproducible signals achieved were comparable to those obtained with separate single-channel devices. Subsequently, the multi-channel microfluidic chip was applied to a model bioanalytical detection strategy, i.e., the quantification of specific nucleic acid sequences using a sandwich approach. Here, probe-coated paramagnetic beads and probe-tagged liposomes entrapping ferri/ferro hexacyanide as the redox marker were used to bind to a single-stranded DNA sequence. Flow rates of the non-ionic detergent n-octyl-β-D-glucopyranoside for liposome lysis were optimized, and the detection of the target sequences was carried out coulometrically within 250 s and with a limit of detection of 12.5 μM. The robustness of the design and the reliability of the results obtained in comparison to previously published single-channel designs suggest that the multi-channel device offers an excellent opportunity for bioanalytical applications that require multianalyte detection and high-throughput assays.

Removal of Ocular Artifacts in EEG—An Improved Approach Combining DWT and ANC for Portable Applications

A new model to remove ocular artifacts (OA) from electroencephalograms (EEGs) is presented. The model is based on discrete wavelet transformation (DWT) and adaptive noise cancellation (ANC). Using simulated and measured data, the accuracy of the model is compared with the accuracy of other existing methods based on stationary wavelet transforms and our previous work based on wavelet packet transform and independent component analysis. A particularly novel feature of the new model is the use of DWTs to construct an OA reference signal, using the three lowest frequency wavelet coefficients of the EEGs. The results show that the new model demonstrates an improved performance with respect to the recovery of true EEG signals and also has a better tracking performance. Because the new model requires only single channel sources, it is well suited for use in portable environments where constraints with respect to acceptable wearable sensor attachments usually dictate single channel devices. The model is also applied and evaluated against data recorded within the EUFP 7 Project--Online Predictive Tools for Intervention in Mental Illness (OPTIMI). The results show that the proposed model is effective in removing OAs and meets the requirements of portable systems used for patient monitoring as typified by the OPTIMI project.

Imaging spin filter for electrons based on specular reflection from iridium (001)

As Stern-Gerlach type spin filters do not work with electrons, spin analysis of electron beams is accomplished by spin-dependent scattering processes based on spin-orbit or exchange interaction. Existing polarimeters are single-channel devices characterized by an inherently low figure of merit (FoM) of typically 10⁻⁴-10⁻³. This single-channel approach is not compatible with parallel imaging microscopes and also not with modern electron spectrometers that acquire a certain energy and angular interval simultaneously. We present a novel type of polarimeter that can transport a full image by making use of k-parallel conservation in low-energy electron diffraction. We studied specular reflection from Ir (001) because this spin-filter crystal provides a high analyzing power combined with a "lifetime" in UHV of a full day. One good working point is centered at 39 eV scattering energy with a broad maximum of 5 eV usable width. A second one at about 10 eV shows a narrower profile but much higher FoM. A relativistic layer-KKR SPLEED calculation shows good agreement with measurements.

THz Oscillations in a GaN Based Planar Nano-Device

Gunn oscillations in a GaN based planar nano-device have been studied by ensemble Monte Carlo (EMC) method. Simulation results show that when the channel length of the device reduces to 450 nm, THz oscillations (about 0.3 THz) can be obtained. Also the phase of the oscillations can be controlled by the initial conditions that excite the Gunn domains. Moreover, through adjusting the phase difference between the oscillations in a double-channels device, which attained by parallel connecting two single-channel devices, the frequency of the device shifts from 0.3 THz to 0.6 THz. This phenomenon remains in devices with shorter channel-length, unless the channel-length is too short to support Gunn oscillations. The possible underlying mechanisms are also discussed.

Horizontally Aligned Carbon Nanotubes on a Quartz Substrate for Chemical and Biological Sensing

We have developed electrolyte-gated sensors based on a field-effect transistor (FET) consisting of horizontally aligned single-walled carbon nanotubes (CNTs) synthesized on single-crystal quartz. Dense well-aligned CNTs serving as device channels enabled high current and large transconductance. Owing to these excellent device properties, the pH resolution was much better in the aligned-channel CNTFETs than in single-channel devices. For immunosensing, selective detection of human immunoglobulin E (IgE) by using aptamer-functionalized CNTFETs was demonstrated in the presence of nontarget proteins at much higher concentration. Moreover, measurements of sensor response versus IgE concentration produced data that fit well to the Langmuir adsorption isotherm. The developed sensors with aligned channels exhibited a drain current of 400-fold that of single-channel devices. Therefore, aligned-channel CNTFETs are useful for highly sensitive and practicable solution sensing.

Choice of biomaterials—Do soft occlusal splints influence jaw-muscle activity during sleep? A preliminary report

AimThe choice of biomaterials for occlusal splints may significantly influence biological outcome. In dentistry, hard acrylic occlusal splints (OS) have been shown to have a temporary and inhibitory effect on jaw-muscle activity, such as tooth clenching and grinding during sleep, i.e., sleep bruxism (SB). Traditionally, this inhibitory effect has been explained by changes in the intraoral condition rather than the specific effects of changes in occlusion. The aim of this preliminary study was to investigate the effect of another type of occlusal surface, such as a soft-material OS in addition to a hard-type OS in terms of changes in jaw-muscle activity during sleep. Materials and methodsSeven healthy subjects (mean±SD, six men and one woman: 28.9±2.7 year old), participated in this study. A soft-material OS (ethylene vinyl acetate copolymer) was fabricated for each subject and the subjects used the OS for five continuous nights. The EMG activity during sleep was compared to baseline (no OS). Furthermore, the EMG activity during the use of a hard-type OS (Michigan-type OS, acrylic resin), and hard-type OS combined with contingent electrical stimulation (CES) was compared to baseline values. Each session was separated by at least two weeks (washout). Jaw-muscle activity during sleep was recorded with single-channel ambulatory devices (GrindCare, MedoTech, Herlev, Denmark) in all sessions for five nights. ResultsJaw-muscle activity during sleep was 46.6±29.8 EMG events/hour at baseline and significantly decreased during the hard-type OS (17.4±10.5, P=0.007) and the hard-type OS+CES (10.8±7.1, P=0.002), but not soft-material OS (36.3±24.5, P=0.055). Interestingly, the soft-material OS (coefficient of variance=98.6±35.3%) was associated with greater night-to-night variations than baseline (39.0±11.8%) and the hard-type OS+CES (53.3±13.7%, P<0.013). ConclusionThe present pilot study in small sample showed that a soft-material occlusal splint does not seem to inhibit jaw-muscle activity during sleep. Within the limitation of the study, it appears that the choice of biomaterials for occlusal splints may have a significant impact on the neurobiological regulation of jaw-muscle activity during sleep.