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Monitoring joystick operations in power wheelchairs (PWCs) is promising for investigating user-wheelchair interaction and providing quantitative measures to assess the user's driving performance. In this paper, an add-on measurement system, Power Wheelchair Maneuvering Logger (PWhML), is developed to provide an easy-to-implement and cost-effective solution for monitoring the user's joystick operations in PWCs. The proposed system uses two compact inertial measurement units (IMUs), which are respectively attached to the joystick and wheelchair armrest for movement sensing. A coordinate transformation-based method is proposed to estimate the joystick operating angles using the acceleration data measured by the attached IMUs. The accuracy of the proposed method was thoroughly evaluated under different conditions. The evaluation trials in a stationary PWC reported a mean absolute error (MAE) of 0.59° in the forward/backward direction and 0.64° in the leftward/rightward direction, validating the established geometry model for coordinate transformation. The subsequent driving experiments on outdoor test courses demonstrated the effectiveness and robustness of the proposed method in various terrain conditions (MAE of less than 3°). A clustering analysis based on the t-distributed stochastic neighborhood embedding method correctly categorized different driving activities using the joystick operating angles measured by PWhML. These results indicate that integrating the developed PWhML into PWCs can facilitate a quantitative measurement of the user's driving behavior, providing valuable insights to identify careless operation patterns and help PWC users to improve driving performance. [ABSTRACT FROM AUTHOR]

With the growing demand from elderly persons for alternative mobility solutions, motorized mobility scooters (MMSs) have been gaining importance as an essential assistive technology to aid independent living in local communities. The increased use of MMSs, however, has raised safety issues during driving and magnified the necessity to evaluate and improve user driving skills. This study is intended to develop a novel quantitative monitoring method for MMS driving operation using inertial measurement units (IMUs). The proposed method used coordinate transformations around the rotational axes of the steering wheel and the throttle lever to estimate the steering and throttle operating angles based on gravitational accelerations measured by IMUs. Consequently, these operating angles can be monitored simply using an IMU attached to the throttle lever. Validation experiments with a test MMS in the stationary state confirmed the consistency of the proposed coordinate transformation with the MMS's geometrical structure. The driving test also demonstrated that the operating angles were estimated correctly on various terrains and that the effects of terrain inclination were compensated using an additional IMU attached to the scooter body. This method will be applicable to the quantitative monitoring of driving behavior and act as a complementary tool for the existing skills' evaluation methods. [ABSTRACT FROM AUTHOR]

To prevent individuals with thermoregulatory dysfunction from becoming hyperthermic in a hot environment, we propose a back-cooling (BC) system with Peltier devices mounted on a wheelchair backrest. Here, we characterize the changes in thermoregulatory responses induced by BC in order to confirm the feasibility of the proposed system. A cooling experiment in a climate chamber at 33°C with six able-bodied subjects demonstrated that the amount of sweating and systolic blood pressure were significantly lower in the BC trials than in the no-cooling trials, providing preliminary evidence that BC can partially replace thermoregulatory responses and reduce the heat burden. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Abstract: To improve the existing light-addressable electrode (LAE) for neuronal stimulation, we attempted to replace a photoconductive layer of hydrogenated amorphous silicon (a-Si:H), which is subject to corrosion in cell culture environments, with a TiO2 nanocrystalline film. As seen in previous LAEs with a-Si:H, the TiO2 film formed on a metal film electrode serves as a photo-switch: UV light illumination locally increases the conductivity of the TiO2 film and generates a virtual electrode. TiO2 is a lower cost material, easier to fabricate than a-Si:H, and more compatible with cell culture environments; thus, it does not require a passivation layer on top. The measurements of photoelectric characteristics of TiO2 LAE ascertained that adequate photo-switching properties for selective neuronal stimulation were achieved; however, two possible issues that could affect performance were identified: degradation of the photo-switching property due to electrolyte penetration into the TiO2 film and a slow switching response due to charge carrier trapping into surface defects. Despite these issues, however, the feasibility of light-addressed electrical stimulation with the proposed TiO2 LAE was successfully demonstrated in an experiment using a primary neuron-glia co-culture. Thus, TiO2 is an alternative candidate to a-Si:H in photo-electrochemical biointerfaces. [Copyright &y& Elsevier]

Light addressing is an emerging technique to optically address a virtual electrode on a photoconductive substrate. A thinner photoconductive layer of a light-addressable planar electrode can improve the spatial resolution of the light-addressed electrode. Voltage application to the electrode, however, causes a strong electric field across the thin photoconductive layer with a significant avalanche effect, which induces an undesired increase of dark current. In order to overcome this problem, we investigated how photoconductive-layer thickness and passivation-layer conductivity affect voltage-application-induced bright and dark charge densities. Suppression of the dark charge density with a thick photoconductive layer and a low-conductive passivation layer is found to be a key factor for optimization of the light-addressable electrode. With this design strategy, we developed a novel light-addressable electrode using titanium dioxide as a photoconductor. To suppress the avalanche effect, the thickness of the titanium-dioxide layer was designed to be 1.5 μm. The fabricated electrode turned out to have sufficient photoelectric properties: the bright charge density reached 70 μC/cm and the bright-to-dark charge density ratio was greater than 10, which allows stimulation to cultured dissociated neurons. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 94(1): 61-68, 2011; Published online in Wiley Online Library (). DOI 10.1002/ecj.10241 [ABSTRACT FROM AUTHOR]

Information transfer among neuronal populations has a directional bias. Some past studies demonstrated that microstructure could bias the direction of information transfer at a cellular level. However, the transfer at a population level has hardly been controlled to date. In order to control the information transfer, we attempt to bias the direction of neurite outgrowth of cultured neurons using a three-dimensional asymmetric microstructure. The proposed microstructure is an embossed barrier with a right-triangle cross section, namely, an ascending slope and vertical wall. Because of the asymmetricity, the neurite growth rate from the wall-side to the slope-side is expected to be lower than that of the slope-to-wall. We fabricated the microstructure on a polystyrene substrate by hot pressing, simultaneously embedding line electrodes for probing stimulation. To confirm the impact of the microstructure on neurite outgrowth, and thus the signal transfer direction between neuronal populations separated by the structure, we stimulated cultured neurons on both sides of the structure. There was a difference in neuronal responses to wall-side stimulation and slope-side stimulation, demonstrating the directional characteristic of information transfer. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(12): 17-25, 2010; Published online in Wiley Online Library (). DOI 10.1002/ecj.10240 [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a light-addressable electrolytic system to produce microscale pH gradients. Light illumination to a photoconductive planar electrode generates a conducting point serving as a photo-anode or cathode, where applied positive or negative voltage electrolytically produces protons or hydroxide ions leading to an increased or decreased pH gradient. A digital micromirror device (DMD) was installed in this system to provide a patterned light illumination. This flexible spatial addressability is a great advantage over previous on-chip pH gradient generation systems with metal thin film microelectrodes. The fluorescence pH imaging showed a proof of principle that electrolysis at the addressed photo-anodes and cathodes could generate localized pH gradients. The spatio-temporal patternability of photo-electrodes allowed characterization of various gradient profiles without any re-fabrication of electrode patterns, a prerequisite in conventional electrolytic generation with metal thin film microelectrodes. A spatio-temporal switching between the photo-anode and cathode allowing use of a combination of bimodal electrolysis enabled the fine-tuning of gradient profiles and enriched the variety of available gradient patterns. [ABSTRACT FROM AUTHOR]

Light addressing is an emerging and sophisticated technique that can induce pinpoint and/or patterned neuronal activation in cultured neurons. We previously developed a light-addressable electrode using hydrogenated amorphous silicon (α-Si:H), which was sandwiched between a tin oxide (SnO2) substrate and a passivation layer of zinc antimonate (ZnOSb2O5) dispersed epoxy. This research developed an experimental system that simultaneously implemented light-addressed stimulation and Ca2+ imaging of neuronal activities. The translucent and thin laminated structure of our electrode permitted optical accesses from two directions: Ca2+ imaging from above and light addressing from beneath. The submillisecond bright/dark switching property of our electrode offered light-addressed stimulation without causing interference with Ca2+ imaging. To provide patterned illumination for light addressing, a digital micromirror device was installed in the system as an active photomask. The system could induce pinpoint neuronal activation at a cellular level. [ABSTRACT FROM AUTHOR]

This paper proposes a penetration-type tungsten microelectrode array on a flexible silicone rubber substrate for neural recording from a desired cortical layer. Our evaluation experiments confirmed that the flexible substrate keeps the penetration depth of each electrode constant and allows simultaneous multipoint recording of spike potentials from a desired neocortical layer. Penetration of the stiff and flexible arrays into agarose specimens with a curvature comparable to that of the rat brain, revealed that the electrodes at the edge of the stiff array had up to 150 μm error in penetration depth, while the penetration depth of the flexible array was approximately constant across the electrodes (ANOVA, p=0.835). Electrophysiological experiments in the rat auditory cortex demonstrated that simultaneous multipoint recording of the acoustically evoked spike potentials was feasible with the flexible array. A series of penetration trials and characteristic frequency estimations successfully identified the primary auditory cortex by assuring a gradual increase in the characteristic frequencies from caudal to rostral. This result suggests that the proposed electrode is suitable for acute experiments requiring repeated penetration and precision positioning of penetration sites. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(7): 21-28, 2009; Published online in Wiley InterScience (). DOI 10.1002/ecj.10060 [ABSTRACT FROM AUTHOR]

This paper provides a detailed process flow for fabricating an easy-to-prepare, inexpensive, dense array of tungsten microelectrodes. We designed the process flow to minimize routine tasks by separating an initial preparation of a master mold from a routine preparation of substrate replication, array assembly and tip processing. Sandblast processing first produced a glass mold with a pattern of a series of protruding lines at a requested interval of a few hundred micrometers. Copying the groove pattern onto polystyrene mass-produced a replica substrate. Tungsten probes were then aligned on the substrate, and the tips of probes were finely processed in the block. [ABSTRACT FROM AUTHOR]

In order to improve direction stability of a power wheelchair on a cross-sloped surface, a downhill turning prevention control (DTPC) has been developed by some researchers and wheelchair suppliers. The DTPC-induced effect on wheelchair maneuver, however, has not been well clarified. In this study, we quantitatively assessed DTPC-induced changes in joystick control strategies during a driving task on a cross-sloped test course. Among several evaluation measures calculated from the joystick inputs during the test trials, the x-axis joystick displacement amount was found to be significantly decreased by the DTPC. This result suggests that the DTPC can save wheelchair users from the burden of compensation control on cross-sloped surfaces. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The authors propose a light-addressable planar electrode with a simple three-layer laminated structure that can induce pinpoint neuronal activation on the culture substrate. The structure consists of a tin oxide (SnO2), hydrogenated amorphous silicon (a-Si:H), and passivation layer. The passivation layer was a spin-coated low-conductive zinc antimonate (ZnOSb2O5)-dispersed epoxy, which was proved to be effective for preventing penetration of culture medium and thus avoiding deterioration of a-Si:H layer. Illumination to the electrode locally elevated the conductivity with 60-fold stimulus charge density. The fluo-4 calcium imaging of neurons cultured on the developed electrode showed that the neuronal activation was confined around the illuminated location, thus demonstrating the light-addressing capability of the proposed electrode. [ABSTRACT FROM AUTHOR]

Background: Clinical evaluation of novel assistive technologies is of utmost importance, as this would help in making such technologies practical and ensuring that they suit the user's requirements. Objective: The purpose of this study is to develop a new methodology for the addition of user and user's life centered clinical evaluation of assistive technologies (ULCEAT) to conventional evaluation methods. The proposed ULCEAT methodology consists of two steps: evaluation by rehabilitation professionals and evaluation by potential users. These evaluations were performed to identify target users and to ensure the effective use of new assistive technologies (ATs); the evaluations were based primarily on qualitative research involving the rehabilitation professionals and the potential users. Methods: The methodology was demonstrated by using it for the clinical evaluation of Roboticbed®, which was developed by the Panasonic Corporation. Results: The effective use of Roboticbed® was confirmed on the basis of the results, and three target user types were identified. The validity of this methodology was further confirmed by a user evaluation of Roboticbed® in an experimental environment. Conclusions: The findings of this study will be used to help conduct conventional clinical evaluations for novel and prototype ATs. [ABSTRACT FROM AUTHOR]

Abstract: Individual neurons are heterogeneous and have profound impact on population activity in a complex cortical network. Precise experimental control of the firing of multiple neurons would be therefore beneficial to advance our understanding of cell–network interactions. Except for direct intracellular stimulation, however, it is difficult to gain precise control of targeted neurons without inducing antidromic activation of untargeted neurons. To overcome this problem, we attempt to create a sparse group of photosensitized neurons via transfection of Channelrhodopsin-2 (ChR2) in primary dissociated cultures and then deliver light-addressed stimulation exclusively to these target neurons. We first show that liposome transfection was able to express ChR2 in 0.3–1.9% of cells plated depending on cell density. This spatially sparse but robust expression in our neuronal cultures offered the capability of single cell activation by illuminating a spot of light. We then demonstrated that delivering a pulsed train to photo-activate a single neuron had a substantial effect on the activity level of an entire neuronal culture. Furthermore, the activity level was controllable by altering the frequency of light illumination when 4 neurons were recruited as stimulation targets. These results suggest that organized activation of a very small population of neurons can provide better control over global activity of neuronal circuits than can single-neuron activities by themselves. [Copyright &y& Elsevier]