25 research outputs found
Portable haptic device for lower limb amputee gait feedback: Assessing static and dynamic perceptibility
Loss of joints and severed sensory pathway cause reduced mobility capabilities in lower limb amputees. Although prosthetic devices attempt to restore normal mobility functions, lack of awareness and control of limb placement increase the risk of falling and causing amputee to have high level of visual dependency. Haptic feedback can serve as a cue for gait events during ambulation thus providing sense of awareness of the limb position. This paper presents a wireless wearable skin stretch haptic device to be fitted around the thigh region. The movement profile of the device was characterized and a preliminary work with able-bodied participants and an above-knee amputee to assess the ability of users to perceive the delivered stimuli during static and dynamic mode is reported. Perceptibility was found to be increasing with stretch magnitude. It was observed that a higher magnitude of stretch was needed for the stimuli to be accurately perceived during walking in comparison to static standing, most likely due to the intense movement of the muscle and increased motor skills demand during walking activity
Real-time gait event detection using a miniature gyroscope to improve rehabilitation for artificial lower limb users
This paper presents a simple heuristic rule based on real-time gait event detection algorithm for transfemoral amputees based on gyroscope signal and validate with footswitches for ramp activities with different inclinatio
A Wearable Skin Stretch Haptic Feedback Device: Towards Improving Balance Control in Lower Limb Amputees
Haptic feedback to lower limb amputees is essential to maximize the functionality of a prosthetic device by providing information to the user about the interaction with the environment and the position of the prostheses in space. Severed sensory pathway and the absence of connection between the prosthesis and the Central Nervous System (CNS) after lower limb amputation reduces balance control, increases visual dependency and increases risk of falls among amputees. This work describes the design of a wearable haptic feedback device for lower limb amputees using lateral skin-stretch modality intended to serve as a feedback cue during ambulation. A feedback scheme was proposed based on gait event detection for possible real-time postural adjustment. Preliminary perceptual test with healthy subjects in static condition was carried out and the results indicated over 98% accuracy in determining stimuli location around the upper leg region, suggesting good perceptibility of the delivered stimuli
Muscle Synergy Analysis in Transtibial Amputee during Ramp Ascending Activity
In developed countries, the highest number of amputees are elderly with transtibial amputation. Walking on inclined surfaces is difficult for amputees due to loss of muscle volume and strength thereby transtibial amputees (TA) rely on the intact limb to maintain stability. The aim of this study was to use the concatenated non-negative matrix factorization (CNMF) technique to calculate muscle synergy components and compare the difference in muscle synergies and their associated activation profiles in the healthy and amputee groups during ramp ascending (RA) activity. Healthy subjects' dominant leg and amputee's intact leg (IL) were considered for recording surface electromyography (sEMG). The muscle synergies comparison showed a reasonable correlation between the healthy and amputee groups. This suggests the central nervous system (CNS) activates the same group of muscles synergistically. However, the activation coefficient profile (C) results indicated statistically significant difference (p <; 0.05) in some parts of the gait cycle (GC) in healthy and amputee groups. The difference exhibited in activation profiles of amputee's IL could be due to the instability of the prosthetic leg during the GC which resulted in alteration of the IL muscles activations. This information will be useful in rehabilitation and in the future development of prosthetic devices by using the IL muscles information to control the prostheses
Real-time gait event detection for transfemoral amputees during ramp ascending and descending
Events and phases detection of the human gait are vital for controlling prosthesis, orthosis and functional electrical stimulation (FES) systems. Wearable sensors are inexpensive, portable and have fast processing capability. They are frequently used to assess spatio-temporal, kinematic and kinetic parameters of the human gait which in turn provide more details about the human voluntary control and ampute-eprosthesis interaction. This paper presents a reliable real-time gait event detection algorithm based on simple heuristics approach, applicable to signals from tri-axial gyroscope for lower limb amputees during ramp ascending and descending. Experimental validation is done by comparing the results of gyroscope signal with footswitches. For healthy subjects, the mean difference between events detected by gyroscope and footswitches is 14 ms and 10.5 ms for initial contact (IC) whereas for toe off (TO) it is -5 ms and -25 ms for ramp up and down respectively. For transfemoral amputee, the error is slightly higher either due to the placement of footswitches underneath the foot or the lack of proper knee flexion and ankle plantarflexion/dorsiflexion during ramp up and down. Finally, repeatability tests showed promising results
A Real-Time Gait Event Detection for Lower Limb Prosthesis Control and Evaluation
Lower extremity amputees suffer from mobility limitations which will result in a degradation of their quality of life. Wearable sensors are frequently used to assess spatio-temporal, kinematic and kinetic parameters providing the means to establish an interactive control of the amputee-prosthesis-environment system. Gait events and the gait phase detection of an amputee’s locomotion are vital for controlling lower limb prosthetic devices. The paper presents an approach to real-time gait event detection for lower limb amputees using a wireless gyroscope attached to the shank when performing level ground and ramp activities. The results were validated using both healthy and amputee subjects and showed that the time differences in identifying Initial Contact (IC) and Toe Off (TO) events were larger in a transfemoral amputee when compared to the control subjects and a transtibial amputee (TTA). Overall, the time difference latency lies within a range of ± 50 ms while the detection rate was 100% for all activities. Based on the validated results, the IC and TO events can be accurately detected using the proposed system in both control subjects and amputees when performing activities of daily living and can also be utilized in the clinical setup for rehabilitation and assessing the performance of lower limb prosthesis users
Real-time gait event detection for lower limb amputees using a single wearable sensor
This paper presents a rule-based real-time gait event/phase detection system (R-GEDS) using a shank mounted inertial measurement unit (IMU) for lower limb amputees during the level ground walking. Development of the algorithm is based on the shank angular velocity in the sagittal plane and linear acceleration signal in the shank longitudinal direction. System performance was evaluated with four control subjects (CS) and one transfemoral amputee (TFA) and the results were validated with four FlexiForce footswitches (FSW). The results showed a data latency for initial contact (IC) and toe off (TO) within a range of ± 40 ms for both CS and TFA. A delay of about 3.7 ± 62 ms for a foot-flat start (FFS) and an early detection of -9.4 ± 66 ms for heel-off (HO) was found for CS. Prosthetic side showed an early detection of -105 ± 95 ms for FFS whereas intact side showed a delay of 141 ±73 ms for HO. The difference in the kinematics of the TFA and CS is one of the potential reasons for high variations in the time difference. Overall, detection accuracy was 99.78% for all the events in both groups. Based on the validated results, the proposed system can be used to accurately detect the temporal gait events in real-time that leads to the detection of gait phase system and therefore, can be utilized in gait analysis applications and the control of lower limb prostheses
Heuristic Real-Time Detection of Temporal Gait Events for Lower Limb Amputees
This paper presents a complete system and algorithm to estimate temporal gait events during stance and inner-stance phases using a single inertial measurement unit (IMU) in real-time. Validation of the proposed system was carried out by placing the foot-switches (FSW) directly underneath the foot. The performance of the system was assessed with eleven control subjects (CS), one unilateral transfemoral amputee (TFA), and one unilateral transtibial amputee (TTA), while performing level ground walk and ramp activities. The experimental results showed reasonable agreement in timing differences of all the gait events in both groups when compared against the reference system. However, high data latency was observed for TFA in the case of Foot-Flat Start (FFS) and Heel-Off (HO). The slight variation in the positioning of IMU on the shank and the foot-switches underneath the foot and the difference in the kinematics of CS and lower limb amputees are probable reasons for large variations in the time difference. Overall, the detection accuracy was found to be 100% for Initial Contact, FFS, and Toe-Off, and 98.3% for HO. In addition, a high correlation was observed between estimated stance phase duration (SPD) from IMU and the SPD from FSW data. The proposed system showed high accuracy in the detection of temporal gait events which could potentially be employed in the gait analysis applications and the finite-state control of lower limb prostheses/orthoses
Sex-dimorphism in Cardiac Nutrigenomics: effect of Trans fat and/or Monosodium Glutamate consumption
<p>Abstract</p> <p>Background</p> <p>A paucity of information on biological sex-specific differences in cardiac gene expression in response to diet has prompted this present nutrigenomics investigation.</p> <p>Sexual dimorphism exists in the physiological and transcriptional response to diet, particularly in response to high-fat feeding. Consumption of <it>Trans</it>-fatty acids (TFA) has been linked to substantially increased risk of heart disease, in which sexual dimorphism is apparent, with males suffering a higher disease rate. Impairment of the cardiovascular system has been noted in animals exposed to Monosodium Glutamate (MSG) during the neonatal period, and sexual dimorphism in the growth axis of MSG-treated animals has previously been noted. Processed foods may contain both TFA and MSG.</p> <p>Methods</p> <p>We examined physiological differences and changes in gene expression in response to TFA and/or MSG consumption compared to a control diet, in male and female C57BL/6J mice.</p> <p>Results</p> <p>Heart and % body weight increases were greater in TFA-fed mice, who also exhibited dyslipidemia (P < 0.05). Hearts from MSG-fed females weighed less than males (P < 0.05). 2-factor ANOVA indicated that the TFA diet induced over twice as many cardiac differentially expressed genes (DEGs) in males compared to females (P < 0.001); and 4 times as many male DEGs were downregulated including <it>Gata4</it>, <it>Mef2d </it>and <it>Srebf2</it>. Enrichment of functional Gene Ontology (GO) categories were related to transcription, phosphorylation and anatomic structure (P < 0.01). A number of genes were upregulated in males and downregulated in females, including pro-apoptotic histone deacetylase-2 (HDAC2). Sexual dimorphism was also observed in cardiac transcription from MSG-fed animals, with both sexes upregulating approximately 100 DEGs exhibiting sex-specific differences in GO categories. A comparison of cardiac gene expression between all diet combinations together identified a subset of 111 DEGs significant only in males, 64 DEGs significant in females only, and 74 transcripts identified as differentially expressed in response to dietary manipulation in both sexes.</p> <p>Conclusion</p> <p>Our model identified major changes in the cardiac transcriptional profile of TFA and/or MSG-fed mice compared to controls, which was reflected by significant differences in the physiological profile within the 4 diet groups. Identification of sexual dimorphism in cardiac transcription may provide the basis for sex-specific medicine in the future.</p