A starfish robot based on soft and smart modular structure (SMS) actuated by SMA wires.

This paper describes the design, fabrication and locomotion of a starfish robot whose locomotion principle is derived from a starfish. The starfish robot has a number of tentacles or arms extending from its central body in the form of a disk, like the topology of a real starfish. The arm, which is a soft and composite structure (which we call the smart modular structure (SMS)) generating a planar reciprocal motion with a high speed of response upon the actuation provided by the shape memory alloy (SMA) wires, is fabricated from soft and smart materials. Based on the variation in the resistance of the SMA wires during their heating, an adaptive regulation (AR) heating strategy is proposed to (i) avoid overheating of the SMA wires, (ii) provide bending range control and (iii) achieve a high speed of response favorable to successfully propelling the starfish robot. Using a finite-segment method, a thermal dynamic model of the SMS is established to describe its thermal behavior under the AR and a constant heating strategy. A starfish robot with five SMS tentacles was tested with different control parameters to optimize its locomotion speed. As demonstrated in the accompanying video file, the robot successfully propelled in semi-submerged and underwater environments show its locomotion ability in the multi-media, like a real starfish. The propulsion speed of the starfish robot is at least an order of magnitude higher than that of those reported in the literature-thanks to the SMS controlled with the AR strategy.

An individual-specific gait pattern prediction model based on generalized regression neural networks.

Robotics is gaining its popularity in gait rehabilitation. Gait pattern planning is important to ensure that the gait patterns induced by robotic systems are tailored to each individual and varying walking speed. Most research groups planned gait patterns for their robotics systems based on Clinical Gait Analysis (CGA) data. The major problem with the method using the CGA data is that it cannot accommodate inter-subject differences. In addition, CGA data is limited to only one walking speed as per the published data. The objective of this work was to develop an individual-specific gait pattern prediction model for gait pattern planning in the robotic gait rehabilitation systems. The waveforms of lower limb joint angles in the sagittal plane during walking were obtained with a motion capture system. Each waveform was represented and reconstructed by a Fourier coefficient vector which consisted of eleven elements. Generalized regression neural networks (GRNNs) were designed to predict Fourier coefficient vectors from given gait parameters and lower limb anthropometric data. The generated waveforms from the predicted Fourier coefficient vectors were compared to the actual waveforms and CGA waveforms by using the assessment parameters of correlation coefficients, mean absolute deviation (MAD) and threshold absolute deviation (TAD). The results showed that lower limb joint angle waveforms generated by the gait pattern prediction model were closer to the actual waveforms compared to the CGA waveforms.

Detection of abnormal muscle activations during walking following spinal cord injury (SCI).

In order to identify optimal rehabilitation strategies for spinal cord injury (SCI) participants, assessment of impaired walking is required to detect, monitor and quantify movement disorders. In the proposed assessment, ten healthy and seven SCI participants were recruited to perform an over-ground walking test at slow walking speeds. SCI participants were given assistance from physiotherapists, if required, while they were walking. In agreement with other research, larger cadence and smaller step length and swing phase of SCI gait were observed as a result of muscle weakness and resultant gait instability. Muscle activation patterns of seven major leg muscles were collected. The EMG signal was processed by the RMS in frequency domain to represent the muscle activation power, and the distribution of muscle activation was compared between healthy and SCI participants. The alternations of muscle activation within the phases of the gait cycle are highlighted to facilitate our understanding of the underlying muscular activation following SCI. Key differences were observed (p-value=0.0006) in the reduced activation of tibialis anterior (TA) in single stance phase and rectus femoris (RF) in swing phase (p-value=0.0011). We can then conclude that the proposed assessment approach of gait provides valuable information that can be used to target and define therapeutic interventions and their evaluation; hence impacting the functional outcome of SCI individuals.

Synchronized walking coordination for impact-less footpad contact of an overground gait rehabilitation system: NaTUre-gaits.

Due to the labor-intensiveness and the shortage of therapists in the application of most forms of manually assisted gait training in neuro-rehabilitation, robotics rehabilitation gait systems have been developed to contribute in such fields of neuro-rehabilitation. This paper presents an overground gait rehabilitation robot, which consists of a pair of robotic orthosis (RO) connected to pelvic arm (PA) and mounted on a mobile platform (MP). As the robotic orthosis (RO) is connected to pelvic arm (PA), the compensation between the two modules should be considered. Possible problems that may surface during overground walking include: 1. Ground impact problem. 2. Poor coordination to mobile platform (MP) which would cause foot drag. To reduce, if not to avoid, the ground impact and dragging of the footpad occurring during the course of overground walking with help of the device, a gait motion generation is developed and specified to adjust the gait patterns for an impactless and smooth footpad contact. The initial tests demonstrate the effectiveness and smoothness of the overground walking on the system.

Modulation of weight off-loading level over body-weight supported locomotion training.

With the evolution of robotic systems to facilitate overground walking rehabilitation, it is important to understand the effect of robotic-aided body-weight supported loading on lower limb muscle activity, if we are to optimize neuromotor recovery. To achieve this objective, we have collected and studied electromyography (EMG) data from key muscles in the lower extremity from healthy subjects walking over a wide range of body-weight off-loading levels as provided by a bespoke gait robot. By examining the impact of body-weight off-loading, it was found that muscle activation patterns were sensitive to the level of off-loading. In addition, a large off-loading might introduce disturbance of muscle activation pattern, led to a wider range of motion in terms of dorsiflexion/plantarflexion. Therefore, any future overground training machine should be enhanced to exclude unnecessary effect of body off-loading in securing the sustaining upright posture and providing assist-as-needed BWS over gait rehabilitation.

Subject-specific lower limb waveforms planning via artificial neural network.

Robotic is gaining its popularity in gait rehabilitation. Gait pattern planning is important, in order to ensure the gait patterns induced by robotic systems on the patient are natural and smooth. It is known that the gait parameters (stride length, cadence) are the key factors, which affect gait pattern. However, a systematic methodology for gait pattern planning is missing. Therefore, a gait pattern generation methodology, GaitGen, was proposed in our previous work. In this paper, we introduce a new model to enhance the proposed methodology for generating the joint angle waveforms of the lower limb during walking, with the gait parameters and the lower limb anthropometric data as input. The walking motion was captured with a motion capture system using passive markers. The waveforms of lower limb joint angles were calculated from the experimental data and the waveforms were then decomposed into Fourier coefficients. Therefore, each joint angle waveform can be represented by a Fourier coefficient vector containing eleven elements to facilitate the waveform analysis. Multi-layer perceptron neural networks (MLPNNs) were designed to predict the Fourier coefficient vectors for specific subject and desired gait parameters. Assessment parameters such as correlation coefficient, mean absolute deviation (MAD) and threshold absolute deviation (TAD) were calculated to examine the quality of MLPNNs' prediction. The constructed waveforms from predicted Fourier coefficient vectors were compared with the actual waveforms calculated from experimental data by using the above-mentioned assessment parameters. The results show that the constructed waveforms closely match the experimental waveforms based on the assessment parameter outcomes.

Parametric study of the swimming performance of a fish robot propelled by a flexible caudal fin.

In this paper, we aim to study the swimming performance of fish robots by using a statistical approach. A fish robot employing a carangiform swimming mode had been used as an experimental platform for the performance study. The experiments conducted aim to investigate the effect of various design parameters on the thrust capability of the fish robot with a flexible caudal fin. The controllable parameters associated with the fin include frequency, amplitude of oscillation, aspect ratio and the rigidity of the caudal fin. The significance of these parameters was determined in the first set of experiments by using a statistical approach. A more detailed parametric experimental study was then conducted with only those significant parameters. As a result, the parametric study could be completed with a reduced number of experiments and time spent. With the obtained experimental result, we were able to understand the relationship between various parameters and a possible adjustment of parameters to obtain a higher thrust. The proposed statistical method for experimentation provides an objective and thorough analysis of the effects of individual or combinations of parameters on the swimming performance. Such an efficient experimental design helps to optimize the process and determine factors that influence variability.

Thermosensitive splicing of a clock gene and seasonal adaptation.

Similar to many diurnal animals, the daily distribution of activity in Drosophila exhibits a bimodal pattern with clock-controlled morning and evening peaks separated by a midday "siesta." In prior work, we showed that the thermosensitive splicing of a 3'-terminal intron in the RNA product from the Drosophila period (per) gene (dper) is critical for temperature-induced adjustments in the timing of evening activity. Cold temperatures enhance the splicing efficiency of this intron (termed dmpi8, Drosophila melanogaster per intron 8), an event that stimulates the daily accumulation of dper RNA and protein, leading to earlier evening activity. Conversely, warm temperatures attenuate dmpi8 splicing efficiency contributing to delayed evening activity, likely ensuring that flies avoid activity during the hot midday sun when they are at increased risk of desiccation. Here, we discuss the underlying molecular mechanisms governing the thermosensitive splicing of dmpi8 and how it contributes to seasonal changes in the daily activity patterns of Drosophila. On a broader perspective, RNA-RNA interactions likely have fundamental roles in the thermal adaptation of life forms to the daily and seasonal changes in temperature.

Characterization of microfeatures in selective laser sintered drug delivery devices.

From initial applications in the fields of prosthesis, implants, surgery planning, anthropology, paleontology and forensics, the scope of rapid prototyping (RP) biomedical applications has expanded to include areas in tissue engineering (TE) and controlled drug delivery. In the current investigation, the feasibility of utilizing selective laser sintering (SLS) to fabricate polymeric drug delivery devices (DDDs) that are difficult to make using conventional production methods was studied. Two features, namely porous microstructure and dense wall formation, inherent in SLS fabricated parts were investigated for their potential roles in drug storage and controlling the release of drugs through the diffusion process. A study to determine the influence of key SLS process parameters on dense wall formation and porous microstructure of SLS fabricated parts was carried out. Composite-type DDDs incorporating dense wall and porous matrix features were designed and fabricated using SLS. The characteristics of the fabricated devices were investigated through microstructural examination and in vitro release tests carried out using a drug model or dye in a simulated body environment.

Analysis of 'natural' and vaccine-induced haemophilus influenzae type B capsular polysaccharide serum antibodies for 3H1, a V3-23-associated idiotope.

The variable (V-) region repertoire of antibodies (Abs) to Haemophilus influenzae capsular polysaccharide (Hib PS) has been extensively studied in individuals vaccinated against the microbe, but to a lesser extent in subjects who generated such Abs in response to a 'natural' encounter with this microbe or its antigenic mimics. To gain an insight into the repertoire of Hib PS-reactive Abs in vaccinated and non-vaccinated individuals, we used a monoclonal Ab, 3H1, which detects an idiotypic marker associated with an Ab V-region gene, V3-23. We show here that Hib PS-reactive Abs with detectable 3H1 idiotope can be quantified by an indirect inimunoezymatic assay in serum samples of non-vaccinated healthy adults as well as of recently vaccinated healthy infants. The percentage of Abs that was simultaneously Hib PS-reactive and 3H1-positive ranged widely (from 0 to 68%) among individual serum samples from both groups of subjects. No dramatic differences in the expression of 3H1 idiotope on Hib PS-reactive Abs were found between vaccinated and non-vaccinated individuals. Our results are consistent with the hypothesis that the utilization of V-region genes in Hib PS-reactive Abs that individuals generate after a 'natural' encounter with Hib PS or its mimics is similar to that in these Abs elicited by Hib PS conjugate vaccines.

Pain relief with intravenous regional guanethedine in post-traumatic reflex sympathetic dystrophy--a case report.

Intravenous regional guanethedine (IVRG), using the Bier's block technique, was given to relieve pain in a 62 year old Indian woman suffering from reflex sympathetic dystrophy. The patient obtained complete pain relief with 2 injections and has remained pain-free for 18 months.