A self-referenced optical intensity sensor network using POFBGs for biomedical applications

This work bridges the gap between the remote interrogation of multiple optical sensors and the advantages of using inherently biocompatible low-cost polymer optical fiber (POF)-based photonic sensing. A novel hybrid sensor network combining both silica fiber Bragg gratings (FBG) and polymer FBGs (POFBG) is analyzed. The topology is compatible with WDM networks so multiple remote sensors can be addressed providing high scalability. A central monitoring unit with virtual data processing is implemented, which could be remotely located up to units of km away. The feasibility of the proposed solution for potential medical environments and biomedical applications is shown

Quantitative EMG Changes During 12-Week DeLorme's Axiom Strength Training

Strength training is one of the most common exercises practiced in the field of physical therapy or sports training. However, limited methodology is available to evaluate its effect on the target muscle. This study aimed to test the hypothesis that surface electromyographic (EMG) data from both isometric and isotonic exercise can express changes within the muscle during a 12-week strength training program. Ten healthy male volunteer students (5 for training, 5 for controls) from Yonsei University were recruited for evaluation in this study. DeLorme's axiom was practiced for 12 weeks in the dominant elbow flexors and knee extensors of the training group. Tension for 1 repetition maximum and maximal voluntary isometric contraction, and surface EMG information such as the integrated EMG and three variables from the regression line of median frequency (MDF) data were measured at weeks 0, 3, 6, 9, and 12. The limb circumference was measured at weeks 0 and 12. During the strength training, which was enough for the increment of muscle strength and limb circumference, the rectified-integrated EMG and initial MDF increased with a significant linear pattern in both types of contraction. The two surface EMG variables were able to monitor the physiologic muscle changes during the training. Based on these results, we propose that these two surface EMG variables can be used for monitoring electrophysiological changes in the specific muscle that is undergoing the training program, under conditions where the contraction mode for EMG data collection is either static or dynamic

Cognitive Contributions to Anterior Cruciate Ligament Injury Risk

The purpose of this dissertation was to explore how cognitive factors contribute to non-contact anterior cruciate ligament (ACL) injury risk in young females. We specifically wanted to develop a better understanding of how the movement patterns of females with varying cognitive attributes/abilities are influenced as the cognitive demands associated with a task progress (Chapter 2). We also wanted to explore how task-related cognitive demands influence movement. We altered the cognitive demands associated with a movement task by requiring participants to execute a maneuver while attending to a simulated teammate (Chapter 3) or to a ball overhead (Chapters 4 & 5). In addition, we also imposed temporal constraints on decision-making (i.e. movement selection) by requiring participants to maneuver in response to an external stimulus (Chapters 4 & 5). To investigate the influence of individual cognitive attributes, we utilized a computer-based clinical test to assess cognitive function for a group of 45 uninjured young females. The cohort was delineated into groups based on their performance on the reaction time component of the cognitive test (slow reaction times vs. fast reaction times). Both groups also performed a lateral cutting task in two conditions (un-planned, pre-planned). For the un-planned condition, participants initiated a trial and then reacted to a stimulus that dictated the movement they were to perform (land, jump, or cut), which imposed temporal constraints on decision-making. During the pre-planned condition, participants knew to perform the cut prior to initiating a trial. We expected that the mechanics of the participants with slower reaction times would be influenced to a greater extent when there were temporal constraints on decision-making. Interestingly, this was not the case. In fact, we found that the participants with slower reaction times landed with greater forces regardless of the cognitive demands associated with the task. It appears that cognitive function plays a prominent role in an individual’s ability to control their movement, even when there are not additional cognitive demands imposed. Our assessment of the impact of additional task-related cognitive demands on movement included 20 uninjured young females with basketball experience. In our first analysis, we found that requiring participants to perform a basketball chest pass immediately after landing from a cut altered their mechanics in a manner that may increase ACL injury risk in comparison to trials performed without the pass. We also performed an analysis where participants performed a drop vertical jump task with and without additional cognitive demands. When temporal constraints were imposed on decision-making, participants demonstrated landing mechanics that may increase their ACL injury risk compared to baseline (i.e. trials performed without additional cognitive demands). We found similar results when participants were required to attend to a ball suspended overhead during execution of the drop vertical jump. Our findings indicate that additional task-related cognitive demands have a prominent influence on movement. The results of this dissertation highlight how cognitive factors (individual and task-related) may contribute to non-contact ACL injury risk. Failure to incorporate cognitive factors could limit the effectiveness of ACL injury risk screening and prevention

Can the Voluntary Drive to a Paretic Muscle be Estimated from the Myoelectric Signal during Stimulation?

Patients with SCI sometimes recover lost function after using FES. This phenomenon, known as the carry-over effect, is not fully understood. One theory used to explain this mechanism is that electrical stimulation of the peripheral nerve causes antidromic action potentials to reach the anterior horn cells in time with the patient’s voluntary effort. This may reinforce the motor pathways and consequently restore voluntary control. However, the theory has never been properly tested and testing requires a method of measuring the voluntary drive. This project aims to find out whether it is possible to estimate the voluntary drive from measured myoelectric signals. The project is based on an FES cycling system with the ability to adjust the stimulation intensity relating to the corresponding voluntary drive. In paretic muscles, the weak voluntary contraction produces an EMG response. The EMG signal cannot be used directly as an indication of the voluntary drive because of the presence of stimulus artefact and reflexes. Two methods were investigated to estimate the voluntary drive. A time domain method was tested using RMS EMG extracted from a range of time windows following the stimulation pulse. This approach was unsatisfactory because the large variations seen in the RMS EMG amplitudes for the same power output as well as the low sensitivity of it to the change of power output. A frequency domain approach was then tested using coherence between co-contracting muscles. It was encouraging to see that the area under the coherence curve in the β band reflected changes in the power output level. However, further tests showed that this area was also greatly influenced by exercise time, becoming unpredictable after 3 minutes. In conclusion, neither of the two methods of using the myoelectric signal from muscles under stimulation is practical for the estimation of voluntary drive

Towards an Intelligent Intervertebral Disc Prosthesis for the Assessment of Spinal Loading

Low back pain is an economic and social burden to society. Low back pain is considered to be a chronic problem when the causes are due degenerative disc diseases and damaged vertebrae. The main causes for degenerative disc are extremely complex and still not well understood, although in their majority are strongly related to the acute and frequent mechanical loading on the spine. Knowledge that might shed more light on such pathologies is the availability of in vivo human spinal disc loading data, which at the moment does not exist. Many efforts had been made by researchers to investigate and understand the in vivo loading of the human spinal disc. All such techniques were not true in vivo techniques and hence, their findings are questionable. Not only a full understanding of the in vivo loading of the human spine, but also the distribution of the loading on the spinal disc are of prime importance in order to comprehensively understand the biomechanics of the human spine. Such new knowledge will also be helpful in the treatment of vertebrae compression fractures and also aid in the further improvement of current implantable spinal technologies. The aim of this work was to engage in such investigation by developing a prototype intelligent artificial spinal disc with the capability of mapping the loads applied to the disc when it's loaded in an in vitro and ex vivo environment. In this research, for the first time a commercial artificial intervertebral disc prosthesis was used as a base for a load-cell. Following a critical review of possible suitable sensors to be embedded within the artificial spinal disc, it was concluded that strain gauges and piezoresistive thin layer sensors were the most appropriate for incorporation within the body of the artificial spinal disc. The loading cell has been successfully designed and developed comprising of eight strain gauges and two piezoresistive sensors encapsulated inside the body of the artificial spinal disc. Further instrumentation and software were developed in order to interface the loading cell with a data acquisition system. A universal testing machine was used for all loading experiments. In vitro and ex vivo (using an animal spine) experiments were conducted in order to evaluate the developed technology and also to rigorously investigate the loading behaviour of the new loading cell. Following the in vitro and ex vivo experiments, it can be concluded that all the sensors' outputs are almost identical in characteristics. All results are very much predictable with moderate level of tolerances, uncertainty, accuracy and repeatability. Such results suggest that this new intelligent artificial intervertebral disc prosthesis could allow the in vivo investigation of loading on the human spine in the lumbar region and therefore enable the continuous postoperative assessment of patients that had a spinal disc surgical intervention

Boundaries in volatile organic compounds in human breath

Exhaled breath is a rich and complex matrix containing many hundreds of compounds. Every breath offers the potential of a non-invasive measurement of the biochemical processes occurring in the human body and it is this notion that has led to the application of breath analysis for the detection of disease. With the majority of research in the field being focused on the detection of biomarkers, little has been presented on how the seemingly homeostatic matrix of breath varies during the course of normal life events. The research in this thesis describes how a subject’s emotional state, physical state, and daily activities can alter the composition of exhaled breath. [Continues.

Biomechanical study of rigid ankle-foot orthoses in the treatment of stroke patients

Error on title page, date of award is 2021.Rigid Ankle-Foot Orthoses (AFOs) are commonly prescribed for stroke patients who exhibit equinovarus deformity as an orthotic intervention. The main purpose of prescribing a rigid AFO is to provide appropriate control of unwanted ankle and foot motions in any plane. To achieve the optimal effects of the AFO, appropriate stiffness and alignment optimisation (tuning) should be considered. The AFO provides moments (referred to as the orthotic moments) to control ankle motion. Orthotic moments are different from the moments generated by ground reaction forces, the later are known as total ankle moments. Reviewing the literature showed limited research in this area. The aims of this study are to investigate the biomechanical effects of using rigid AFO (before and after tuning) and to investigate the orthotic moment during walking in stroke patients. Gait data were collected from six stroke participants (2 females, 4 males) and six healthy participants (3 females, 3 males) using a Motekforce Link dual belt instrumented treadmill and a Vicon 3-dimensional motion analysis system. Each participant was fitted with a custom made rigid AFO instrumented using four strain gauges. Walking at a self-selected speed was investigated while wearing: (1) Standard shoes only (2) Rigid AFO with standard shoes (3) Rigid Tuned-AFO with standard shoes. Lower limb temporal-spatial, kinetic and kinematic parameters, and electromyographic activity (Delsys TrignoTM) of the knee muscles were compared among the test conditions. The orthotic moments were also quantified using the strain gauges data combined with gait analysis. Repeated measures ANOVA and Friedman’s ANOVA were used for statistical analysis. The rigid AFO showed immediate improvement in the temporal-spatial parameters and the kinematics and the kinetics of post stroke gait. Greater improvement in knee kinematics and kinetics was achieved when tuning the rigid AFO. The rigid AFO (before and after tuning) increased quadriceps muscle activity and reduced hamstring muscle activity compared to walking with standard shoes only. Tuning a rigid AFO further increased quadriceps muscle activity and reduced hamstring muscle activity compared to AFO before tuning. Strain gauges data combined with gait analysis can be used in evaluating the orthotic moment around the ankle in sagittal and frontal planes. Tuning a rigid AFO had no clear changes in the orthotic moment, and it did not alter the anatomical moments at the ankle joint in sagittal and at the subtalar joint in frontal plane.Rigid Ankle-Foot Orthoses (AFOs) are commonly prescribed for stroke patients who exhibit equinovarus deformity as an orthotic intervention. The main purpose of prescribing a rigid AFO is to provide appropriate control of unwanted ankle and foot motions in any plane. To achieve the optimal effects of the AFO, appropriate stiffness and alignment optimisation (tuning) should be considered. The AFO provides moments (referred to as the orthotic moments) to control ankle motion. Orthotic moments are different from the moments generated by ground reaction forces, the later are known as total ankle moments. Reviewing the literature showed limited research in this area. The aims of this study are to investigate the biomechanical effects of using rigid AFO (before and after tuning) and to investigate the orthotic moment during walking in stroke patients. Gait data were collected from six stroke participants (2 females, 4 males) and six healthy participants (3 females, 3 males) using a Motekforce Link dual belt instrumented treadmill and a Vicon 3-dimensional motion analysis system. Each participant was fitted with a custom made rigid AFO instrumented using four strain gauges. Walking at a self-selected speed was investigated while wearing: (1) Standard shoes only (2) Rigid AFO with standard shoes (3) Rigid Tuned-AFO with standard shoes. Lower limb temporal-spatial, kinetic and kinematic parameters, and electromyographic activity (Delsys TrignoTM) of the knee muscles were compared among the test conditions. The orthotic moments were also quantified using the strain gauges data combined with gait analysis. Repeated measures ANOVA and Friedman’s ANOVA were used for statistical analysis. The rigid AFO showed immediate improvement in the temporal-spatial parameters and the kinematics and the kinetics of post stroke gait. Greater improvement in knee kinematics and kinetics was achieved when tuning the rigid AFO. The rigid AFO (before and after tuning) increased quadriceps muscle activity and reduced hamstring muscle activity compared to walking with standard shoes only. Tuning a rigid AFO further increased quadriceps muscle activity and reduced hamstring muscle activity compared to AFO before tuning. Strain gauges data combined with gait analysis can be used in evaluating the orthotic moment around the ankle in sagittal and frontal planes. Tuning a rigid AFO had no clear changes in the orthotic moment, and it did not alter the anatomical moments at the ankle joint in sagittal and at the subtalar joint in frontal plane

Task planning, execution, and prediction-based coordination with the human wearer

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 87-89).Full automation of repetitive and/or specialized tasks has become a preferred means to meet the needs of manufacturing industries. However, some tasks cannot be fully automated due to their complexity or the nature of the work environment. In such cases, semi-automation through human-robot collaboration is a strong alternative that still maintains a high level of efficiency in task execution. This thesis focused on the control and coordination issues of the Supernumerary Robotic Limbs (SRL); a pair of wearable robotic limbs that are a potential solution to these issues. The first purpose of this study was to adequately model the collaborative aspect of a task that is conventionally performed by two coworkers. This was achieved through the Coloured Petri Nets (CPN) tool, which was able to model the collaboration between two coworkers by using the SRL and its operator instead. The second purpose of this work was to evaluate how to implement a sensor suit to establish reliable communication between the SRL and its operator. Using data-driven methods for detection, we were able to monitor the operator's current state. By combining this data with the CPN task model we were able to relay the operator's intentions to the SRL. This enabled the SRL to follow the CPN process model in a timely and coordinated manner together with its operator. The third and final section of this thesis focused on considering the interchangeability of roles between the SRL and its operator. We used a datadriven approach to model a task where the SRL and its operator had to perform a simultaneous dynamic task. This was performed by using teach by demonstration techniques on process data from two workers. A control algorithm was then extracted from the actions of the supporting worker. Both the process model and the sensor suit, together with the detection algorithms, were implemented and validated using the first prototype of the SRL. Results show that the SRL was successful in autonomously coordinating with its operator and completing an intercostal assembly task.by Baldin Adolfo Llorens - Bonilla.S.M