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  • 1.
    Elhadi, Mustafa M. O.
    et al.
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Ma, Christina Zong-Hao
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Lam, Wing K.
    Li Ning Sports Science Research Center, Li Ning (China) Sports Goods, Co. Ltd., Beijing, China.
    Lee, Winson C.-C.
    School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, Australia.
    Biomechanical approach in facilitating long-distance walking of elderly people using footwear modifications2018In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 64, p. 101-107Article in journal (Refereed)
    Abstract [en]

    Background: Long-distance walking is a convenient way for prompting physical activity of elderly people. However, walking ability declines with aging.

    Research question: This study assessed if silicone insoles with heel lifts (named here the prescribed insoles) could facilitate long-distance walking of older adults.

    Methods: Fifteen adults aged over 65, who did not have obvious lower-limb problems, walked on a treadmill for totally 60 min in two separate walking sessions: 1) with the prescribed insoles, and 2) with original insoles of the standardized shoes. Gait tests using force plates and a motion analysis system, and subjective evaluation using visual analog and Borg's CR10 scales were conducted at different time points of the treadmill walking.

    Results: Objective gait anaylsis showed that without using the prescribed insoles, there were significant reductions (p < 0.05) in stance time, vertical ground reaction force, ankle dorsiflexion angle and ankle power generation of the dominant leg after the 60-minute treadmill walk. Such significant reductions were not observed in the same group of subjects upon using the prescribed insoles. Meanwhile, significant improvements in subjective perception of physical exertion, pain and fatigue were observed.

    Significance: Heel lifts and silicone insoles are generally used to relieve plantar pain and reduce strain of plantar flexors in patients. This study showed they might also be solutions to facilitate long-distance walking of older adults, an approach which could prompt their physical activity. 

  • 2.
    Elhadi, Mustafa M. O.
    et al.
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong.
    Ma, Christina Zong-Hao
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong.
    Wong, Duo W. C.
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong.
    Wan, Anson H. P.
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong.
    Lee, Winson C. C.
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong.
    Comprehensive gait analysis of healthy older adults who have undergone long-distance walking2017In: Journal of Aging and Physical Activity, ISSN 1063-8652, E-ISSN 1543-267X, Vol. 25, no 3, p. 367-377Article in journal (Refereed)
    Abstract [en]

    Many older adults do not adhere to the recommended physical activity levels. This study examines the gait changes upon longdistance walking among healthy older adults. Gait tests of 24 adults aged 65 or more were conducted at baseline and at the end of 30 and 60min of treadmill walking. Spatial temporal, kinematic, and kinetic gait data were computed. Perceived level of exertion was evaluated for each subject. Ten subjects (group B) perceived higher exertion levels than the remaining 14 subjects (group A). After walking, group B had significant reductions in dominant-side ankle joint range of motion and power, suggesting lower-leg muscle fatigue, which appeared to be compensated by significantly increased nondominant-side knee and hip motions. These changes were not observed in group A. Differences in gait parameters between groups A and B implied that some biomechanical factors might contribute to the lack of walking of some older adults. 

  • 3.
    Lam, Wing-Kai
    et al.
    Department of Kinesiology, Shenyang Sport University, Shenyang, China.
    Lee, Winson C.-C.
    School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW, Australia.
    Lee, Wei M.
    Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore, Singapore.
    Ma, Christina Zong-Hao
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Hong Kong, Hong Kong.
    Kong, Pui W.
    Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore, Singapore.
    Segmented forefoot plate in basketball footwear: Does it influence performance and foot joint kinematics and kinetics?2018In: Journal of Applied Biomechanics, ISSN 1065-8483, E-ISSN 1543-2688, Vol. 34, no 1, p. 31-38Article in journal (Refereed)
    Abstract [en]

    This study examined the effects of shoes' segmented forefoot stiffness on athletic performance and ankle and metatarsophalangeal joint kinematics and kinetics in basketball movements. Seventeen university basketball players performed running vertical jumps and 5-msprints atmaximumeffort with 3 basketball shoes of various forefoot plate conditions (medial plate, medial + lateral plates, and no-plate control). One-way repeated measures ANOVAs were used to examine the differences in athletic performance, joint kinematics, and joint kinetics among the 3 footwear conditions (α = .05). Results indicated that participants wearing medial + lateral plates shoes demonstrated 2.9% higher jump height than those wearing control shoes (P = .02), but there was no significant differences between medial plate and control shoes (P > .05). Medial plate shoes produced greater maximum plantar flexion velocity than the medial + lateral plates shoes (P < .05) during sprinting. There were no significant differences in sprint time. These findings implied that inserting plates spanning both the medial and lateral aspects of the forefoot could enhance jumping, but not sprinting performances. The use of a medial plate alone, although induced greater plantar flexion velocity at the metatarsophalangeal joint during sprinting, was not effective in improving jump heights or sprint times.

  • 4.
    Ma, Christina Zong-Hao
    Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Improving balance and gait using biomechanical and electronic approaches2018Doctoral thesis, comprehensive summary (Other academic)
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  • 5.
    Ma, Christina Zong-Hao
    et al.
    Department of Mechanical Engineering, University of Michigan; Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Bao, Tian
    Department of Mechanical Engineering, University of Michigan.
    Le, Victor C.
    Department of Mechanical Engineering, University of Michigan.
    Chambers, April
    Department of Bioengineering, University of Pittsburgh.
    Cham, Rakie
    Department of Bioengineering, University of Pittsburgh, Pittsburgh, USA.
    Shull, Peter
    Department of Mechanical Engineering, Shanghai Jiao Tong University.
    Zheng, Yong-Ping
    Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Sienko, Kathleen H.
    Department of Mechanical Engineering, University of Michigan.
    A feasibility study for gait training with foot-floor contact angle feedback2019Conference paper (Refereed)
    Abstract [en]

    Background and Aim: Slip events are responsible for up to 20% of falls and often result in severe injuries, and significant mortality and morbidity. Prior research has revealed several factors that increase the likelihood of a slip event including walking with a large foot-floor contact angle (FFCA) at heel-strike (>20°). Numerous feedback systems leveraging wearable sensors that measure gait-related kinematic or kinetic data have been used to improve balance and gait performance. In this feasibility study we demonstrated the use of a wearable feedback device for modifying FFCA during treadmill walking.

    Methods: Ten healthy participants (3 females and 7 males, aged 22.0±1.6 years) with fewer than 75% of baseline overground FFCA values falling within a range of 10-20° were recruited for inclusion in the study. A feedback system comprising two IMUs attached to the mid-foot regions of participants' dominant and non-dominant feet to measure FFCA during heel strike events, a laptop for calculating FFCA, and speakers for providing auditory cues to participants was used. Participants received cues during the non-dominant foot stance phase if the average of the two preceding dominant FFCAs was outside of the target range (10-20°). Participants performed 2-min baseline and post-training treadmill trials with a speed of 1.35 m/s prior to and following four 4-min treadmill training trials with FFCA feedback. The percentage of FFCAs within the target range, and the mean and variability of FFCAs were computed for baseline, training, and post-training trials, and one-way repeated measures ANOVA and post-hoc comparisons were performed. The significance level was 0.05.

    Results: Participants increased their percentage of FFCAs within the target range when feedback was provided during the training trials compared to the no feedback condition during the baseline trials (66.9% vs. 53.9%, P=0.028). Increased percentages of FFCAs within the target range were also observed during the post-training trials (75.8% vs. 53.9%, P=0.027). The average FFCA increased from 9.9° during baseline trials to 13.7° during training trials (P=0.028). The FFCAs were less variable during the training (P=0.028) and post-training (P=0.028) trials compared to the baseline trials.

    Conclusions: The findings suggest that participants could use the auditory cues to dynamically adjust their FFCAs while walking on a treadmill and that the training effects were present for a short period of time following the completion of the training. The FFCA is one of several gait parameters that could be used for gait training purposes to potentially reduce the likelihood of a slip event. Future work should examine the effects of gait training with FFCA feedback on the incidence and severity of slips, and on other gait parameters.

  • 6.
    Ma, Christina Zong-Hao
    et al.
    Jönköping University, School of Health and Welfare, HHJ. Prosthetics and Orthotics. The Hong Kong Polytechnic University.
    Chung, Alan Kai-Lun
    The Hong Kong Polytechnic University.
    Ling, Yan To
    The Hong Kong Polytechnic University.
    Huang, Zi-Hao
    The Hong Kong Polytechnic University.
    Cheng, Connie Lok-Kan
    The Hong Kong Polytechnic University.
    Zheng, Yong-Ping
    The Hong Kong Polytechnic University.
    A Newly-Developed Smart Insole System with Instant Reminder: Paves the Way towards Integrating Artificial Intelligence (AI) Technology to Improve Balance and Prevent Falls2019In: Age and Ageing, ISSN 0002-0729, E-ISSN 1468-2834, Vol. 48, no Issue Supplement_4, p. iv28-iv33, article id 121Article in journal (Refereed)
    Abstract [en]

    Background

    Falls in senior people have high incidence& lead to severe injuries [1]. Application of smart wearable systems (with sensors to monitor user’s balance and corresponding instant reminder to let tusers adjust posture/motion) can effectively improve static standing balance [2], reduce reaction time and body sway in response to balance perturbation [3], improve walking pattern [4], and reduce the risk of falls [5, 6]. However, previous systems have not considered the daily monitor of user’s balance and falling risks, and the personalized reminder. Artificial intelligence (AI) and big data analytics have been widely used to monitor the daily physical activity [7], while few studies have utilized them to improve balance/gait and prevent falls.

    Methods

    This study has optimized previous devices by integrating AI technology and developed a new smart insole system. The system consisted of insoles with embedded sensors that can capture the foot motion and plantar pressure, smart watch that connected with insoles wirelessly and then transmitted the foot motion and force data to Cloud server via Wi-Fi, central Cloud server for big data transmission and storage, workstation for big data analytics and machine learning, and user interface for data visualization (e.g. smartphone, tablet, and/or laptop).

    Results & Discussion

    The system transmission rate was up to 30 Hz. The collected big data contained all sensor signals captured before and after delivering reminder, and from day-to-day monitoring of users. The customized reminder varied in the type, frequency, magnitude, and amount/dosage. This AI smart insole system enabled the monitor of daily balance and falling risks and the provision of timely-updated and customized reminder to users, which could potentially reduce the risk of falls and slips. It can also act as a balance-training device.

  • 7.
    Ma, Christina Zong-Hao
    et al.
    Jönköping University, School of Health and Welfare, HHJ, Dep. of Rehabilitation. Department of Mechanical Engineering, University of Michigan; Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Chung, Alan Kai-Lun
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Ling, Yan To
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Huang, Zihao
    ngineering, The Hong Kong Polytechnic University, Hong Kong.
    Cheng, Connie Lok-Kan
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Zheng, Yong-Ping
    Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Smart Insole and Smartwatch System with Big Data Analytics to Improve Balance Training and Walking Ability2019Conference paper (Refereed)
    Abstract [en]

    BACKGROUND 

    Applying wearable motion sensors to capture balance/gait performance and provide the corresponding biofeedback/reminder have been proved effective in improving users’ balance/gait [1-5]. Unfortunately, previous approach of providing pre-set biofeedback did not consider user’s individual balance performance or training process during various tasks. Big data analytics and machine learning technologies have been widely used to monitor the daily physical activity [6-8]. However, few previous studies have utilized these technologies to improve balance/gait training.

    AIM

    This study aimed to develop a foot-motion based smart insole and smartwatch system integrated with big data analytics, and investigate its effect on improvement of balance training in patients with stroke.

    METHOD 

    The newly-developed system with big data analytics can collect and store patients’ balance performance and their response to the reminder/biofeedback during each session of balance/gait training. With the collected huge amount of data (big data) of patients’ balance and response to the biofeedback, the system can identify and extract the feature of patients’ response upon receiving the biofeedback, and further deliver the customized biofeedback (that gradually changed according to the balance improvement) for patients to further improve balance and gait training outcomes (machine learning).

    A randomized controlled trial will be conducted on 12 patients with stroke by evaluating patient’s balance/gait training outcomes with and without using the developed system.

    RESULTS

    The development of hardware of the system were completed, and the development of software were in progress. The system contained: 1) personal unit with force and motion sensors placed at both feet to capture the foot motion, and a smartwatch at wrist to collect data from both feet via Bluetooth and then transmit the data to the central cloud server via WiFi; 2) central cloud servers for data transmission and storage; 3) user interface for data analysis, which included a smartphone, tablet, and/or laptop; and 4) workstation for big data analytics (Figure 1). The collected data involved all sensor signals the system received before and after delivering biofeedback, and from day to day monitoring of patients. The customized biofeedback pattern included various type, frequency, magnitude, and amount/dosage of biofeedback.

    DISCUSSION AND CONCLUSION 

    The introduced system adopted big data and machine learning technologies to provide the repetitive targeted balance and gait training based on each patient’s condition. With further optimization, this system can also be applied in elderly and other patients with balance disorders for various daily tasks, including standing, walking, and obstacle crossing. This will enhance the balance training outcomes and potentially reduce the risk of falls in the future.

    REFERENCES

    1. Ma, C.Z.-H.; 2018 Top Stroke Rehabil.
    2. Ma, C.Z.-H.; 2017 Hum Mov Sci.
    3. Ma, C.Z.-H.; 2016 Sensors.
    4. Ma, C.Z.-H.; 2015 Sensors.
    5. Wan, A.-H.; 2016 Arch Phys Med Rehabil.
    6. Wu, J.; 2017 INT J PROD RES.
    7. Badawi, H.F.; 2017 Future Gener Comput Syst.
    8. Gravina, R.; 2017 Future Gener Comput Syst.

     

    ACKNOWLEDGEMENTS

    This work was partially supported by The Hong Kong Polytechnic University [grant number: G-YBRN].

  • 8.
    Ma, Christina Zong-Hao
    et al.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Lee, Winson C.-C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    A wearable vibrotactile biofeedback system improves balance control of healthy young adults following perturbations from quiet stance2017In: Human Movement Science, ISSN 0167-9457, E-ISSN 1872-7646, Vol. 55, p. 54-60Article in journal (Refereed)
    Abstract [en]

    Maintaining postural equilibrium requires fast reactions and constant adjustments of the center of mass (CoM) position to prevent falls, especially when there is a sudden perturbation of the support surface. During this study, a newly developed wearable feedback system provided immediate vibrotactile clues to users based on plantar force measurement, in an attempt to reduce reaction time and CoM displacement in response to a perturbation of the floor. Ten healthy young adults participated in this study. They stood on a support surface, which suddenly moved in one of four horizontal directions (forward, backward, left and right), with the biofeedback system turned on or off. The testing sequence of the four perturbation directions and the two system conditions (turned on or off) was randomized. The resulting reaction time and CoM displacement were analysed. Results showed that the vibrotactile feedback system significantly improved balance control during translational perturbations. The positive results of this preliminary study highlight the potential of a plantar force measurement based biofeedback system in improving balance under perturbations of the support surface. Future system optimizations could facilitate its application in fall prevention in real life conditions, such as standing in buses or trains that suddenly decelerate or accelerate. 

  • 9.
    Ma, Christina Zong-Hao
    et al.
    Jönköping University, School of Health and Welfare, HHJ. Prosthetics and Orthotics. Jönköping University, School of Health and Welfare, HHJ, Dep. of Rehabilitation. Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Lee, Winson
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Zheng, Yong-Ping
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Foot orthosis could improve elderly balance and gait control by changing plantar mechanical stimulations2016Conference paper (Refereed)
    Abstract [en]

    Background: Plantar sensory input is a crucial component of proprioceptive system, which is important for maintaining balance and gait control. Foot orthoses with arch supports, metatarsal pads, and heel cups are traditionally prescribed to correct/compensate foot deformity and relieve foot pain in patients. It was reported that upon achieving these therapeutic functions, the body balance could also be enhanced [1]. However, the underlying mechanism of such balance improvement and the effect of foot orthoses on dynamic balance and gait in healthy adults without foot pain/deformity remained unclear.

    In this study, we applied custom-fitted foot orthoses with arch supports, metatarsal pads and heel cups among elderly people. The gait variability decreased after using them, suggesting that they were effective in improving elderly balance and gait control.

    Aim: This study aimed to identify the underlying mechanism of balance improvement upon using foot orthoses by investigating the relationship between plantar mechanical stimulations and dynamic balance in healthy older adults without foot pain or deformity.

    Method: Foot orthoses with medial arch supports, metatarsal pads and heel cups (Fig.1) were provided and fitted for healthy older adults by a Certified Orthotist. Subjects then performed over-ground walking while wearing 1) flat insoles (control), or 2) foot orthoses with arch supports, metatarsal pads, and heel cups. The sequence of 2 experimental conditions was randomized, and each condition was repeated 3 times consecutively. Commercially available flat insoles and pads (Foot Specialist Footcare & Products Co. Ltd, HK) were made of medium firm (15-20 Shore A Hardness) ethylene-vinyl acetate (EVA). An in-shoe plantar pressure measurement system (PedarTM, novel GmbH, Munich, DE) was used to measure subject’s plantar pressure distribution and gait parameters in 2 experimental conditions. The variability of gait parameters was calculated.

    Results: Four healthy male older adults (aged 72±4.7 years, height 166.7±29.3 cm, and weight 73.8±4.1 kg) without foot pain/deformity participated in this study. The foot orthosis re-distributed plantar pressure at metatarsal heads, lateral foot and heel to the medial longitudinal arch, metatarsal shafts and margin of the heel (Fig.2). Additionally, the contact area between foot and support surface also increased during walking while wearing custom-fitted foot orthosis as compared to wearing flat insoles (Fig.2). The variability of contact area, maximum ground reaction force, and peak plantar pressure during walking decreased while wearing foot orthosis in participants, indicating reduced gait variability (Fig.3). Subjects also verbally reported that the comfortableness while wearing foot orthosis was higher than wearing flat insoles.

    Discussion & Conclusion: Reduced gait variability is associated with improved dynamic balance performance and reduced risk of falls in older adults. In this study, foot orthosis improved dynamic balance and gait control by changing mechanical stimulations at plantar foot. More specially, foot orthosis  re-distributed plantar pressure to the medial longitudinal arch, metatarsal shafts and margin of the heel, where reveal higher sensitivity to mechanical stimulations [2]; and enlarged the contact area between plantar foot and support surface. The changed plantar mechanical stimulations enhanced sensory input at plantar surface of foot, and consequently improved dynamic balance and gait performance.

    This study revealed that foot orthoses with arch supports, metatarsal pads, and heel cups could improve dynamic balance and gait control in healthy older adults without foot pain or deformity, and further provided evidence about the underlying mechanism of balance and gait improvement. This potentially provided a cost-effective approach to reduce risk of falls and inspired future research in this field.

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  • 10.
    Ma, Christina Zong-Hao
    et al.
    Jönköping University, School of Health and Welfare, HHJ, Dep. of Rehabilitation. Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Ling, Yan To
    Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Shea, Queenie Tsung Kwan
    Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Wang, Li-Ke
    Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Wang, Xiao-Yun
    GuangdongWork Injury Rehabilitation Center.
    Zheng, Yong-Ping
    Department of Biomedical Engineering, The Hong Kong Polytechnic University.
    Towards Wearable Comprehensive Capture and Analysis of Skeletal Muscle Activity during Human Locomotion2019In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 1, article id 195Article in journal (Refereed)
    Abstract [en]

    Background: Motion capture and analyzing systems are essential for understanding locomotion. However, the existing devices are too cumbersome and can be used indoors only. A newly-developed wearable motion capture and measurement system with multiple sensors and ultrasound imaging was introduced in this study. Methods: In ten healthy participants, the changes in muscle area and activity of gastrocnemius, plantarflexion and dorsiflexion of right leg during walking were evaluated by the developed system and the Vicon system. The existence of significant changes in a gait cycle, comparison of the ankle kinetic data captured by the developed system and the Vicon system, and test-retest reliability (evaluated by the intraclass correlation coefficient, ICC) in each channel’s data captured by the developed system were examined. Results: Moderate to good test-retest reliability of various channels of the developed system (0.512 ≤ ICC ≤ 0.988, p < 0.05), significantly high correlation between the developed system and Vicon system in ankle joint angles (0.638R ≤ 0.707, p < 0.05), and significant changes in muscle activity of gastrocnemius during a gait cycle (p < 0.05) were found. Conclusion: A newly developed wearable motion capture and measurement system with ultrasound imaging that can accurately capture the motion of one leg was evaluated in this study, which paves the way towards real-time comprehensive evaluation of muscles and joint motions during different activities in both indoor and outdoor environments.

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  • 11.
    Ma, Christina Zong-Hao
    et al.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Wan, Anson H. -P
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Wong, Duo W.-C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Zheng, Yong-Ping
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Lee, Winson C.-C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    A vibrotactile and plantar force measurement-based biofeedback system: Paving the way towards wearable balance-improving devices2015In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 15, no 12, p. 31709-31722Article in journal (Refereed)
    Abstract [en]

    Although biofeedback systems have been used to improve balance with success, they were confined to hospital training applications. Little attempt has been made to investigate the use of in-shoe plantar force measurement and wireless technology to turn hospital training biofeedback systems into wearable devices. This research developed a wearable biofeedback system which detects body sway by analyzing the plantar force and provides users with the corresponding haptic cues. The effects of this system were evaluated in thirty young and elderly subjects with simulated reduced foot sensation. Subjects performed a Romberg test under three conditions: (1) no socks, system turned-off; (2) wearing five layers of socks, system turned-off; (3) wearing five layers of socks, and system turned-on. Degree of body sway was investigated by computing the center of pressure (COP) movement measured by a floor-mounted force platform. Plantar tactile sensation was evaluated using a monofilament test. Wearing multiple socks significantly decreased the plantar tactile sensory input (p < 0.05), and increased the COP parameters (p < 0.017), indicating increased postural sway. After turning on the biofeedback system, the COP parameters decreased significantly (p < 0.017). The positive results of this study should inspire future development of wearable plantar force-based biofeedback systems for improving balance in people with sensory deficits. 

  • 12.
    Ma, Christina Zong-Hao
    et al.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Wan, Anson H.P.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Wong, Duo W.C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Zheng, Yong-Ping
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Lee, Winson C.C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Improving Postural Control Using a Portable Plantar PressurebasedVibrotactile Biofeedback System2014Conference paper (Refereed)
    Abstract [en]

    A portable and lightweight vibrotactile biofeedback system is introduced here which acts as a real-time balance aid. The biofeedback system provided users with vibrotactile stimulation based on changes in plantar pressure distribution. An experiment was conducted to investigate its effectiveness in improvement of postural control. A Romberg test was performed requesting the subjects to stand as still as possible, while the degree of body sway was measured by a force platform. Two young healthy subjects and one older healthy subject participated in the study. A wearing wool socks and eye-closed intervention was used to simulate reduced sensory input, and the effect of provision of vibrotactile feedback was studied. The experiment was conducted in 3 conditions: 1) bare feet, eyes open (baseline), 2) wearing 5 layers of wool socks, eyes closed, 3) wearing 5 layers of socks, eyes closed, with biofeedback system turned-on. The range, root mean square (RMS) and coefficient of variance (CV) of center of pressure (COP) were studied. Results indicated a significant increase of postural sway after the intervention of reducing sensory inputs, and a considerable reduction of postural sway upon using the vibrotactile feedback reminding body motion in four directions. These results suggested that vibrotactile biofeedback system is effective in improving postural control of subjects. Future studies about the effects of this biofeedback system on dynamic balance control and gait are needed.

  • 13.
    Ma, Christina Zong-Hao
    et al.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Wong, Duo W.-C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Lam, Wing K.
    Li Ning Sports Science Research Center, Beijing, China.
    Wan, Anson H.-P.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Lee, Winson C.-C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Balance improvement effects of biofeedback systems with state-of-the-art wearable sensors: A systematic review2016In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 4, article id 434Article, review/survey (Refereed)
    Abstract [en]

    Falls and fall-induced injuries are major global public health problems. Balance and gait disorders have been the second leading cause of falls. Inertial motion sensors and force sensors have been widely used to monitor both static and dynamic balance performance. Based on the detected performance, instant visual, auditory, electrotactile and vibrotactile biofeedback could be provided to augment the somatosensory input and enhance balance control. This review aims to synthesize the research examining the effect of biofeedback systems, with wearable inertial motion sensors and force sensors, on balance performance. Randomized and non-randomized clinical trials were included in this review. All studies were evaluated based on the methodological quality. Sample characteristics, device design and study characteristics were summarized. Most previous studies suggested that biofeedback devices were effective in enhancing static and dynamic balance in healthy young and older adults, and patients with balance and gait disorders. Attention should be paid to the choice of appropriate types of sensors and biofeedback for different intended purposes. Maximizing the computing capacity of the micro-processer, while minimizing the size of the electronic components, appears to be the future direction of optimizing the devices. Wearable balance-improving devices have their potential of serving as balance aids in daily life, which can be used indoors and outdoors. 

  • 14.
    Ma, Christina Zong-Hao
    et al.
    The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Wong, Duo W.-C.
    The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Wan, Anson H.-P.
    The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Lee, Winson C.-C.
    Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW, Australia.
    Effects of orthopedic insoles on static balance of older adults wearing thick socks2018In: Prosthetics and orthotics international, ISSN 0309-3646, E-ISSN 1746-1553, Vol. 42, no 3, p. 357-362Article in journal (Refereed)
    Abstract [en]

    Background: The wearing of socks and insoles may affect the ability of the foot to detect tactile input influencing postural balance.

    Objectives: The aim of this study was to investigate whether (1) thick socks adversely affected the elderly postural balance and (2) orthopedic insoles could improve the elderly postural balance while wearing thick socks.

    Study design: Repeated-measures study design. Methods: In total, 14 healthy older adults were recruited. A monofilament test was conducted to evaluate foot plantar sensation with and without thick socks. Subjects then performed the Romberg tests under three conditions: (1) barefoot, (2) with socks only, and (3) with both socks and insoles. Postural balance was assessed by measuring the center of pressure movement during standing in each experimental condition.

    Results: Thick socks significantly decreased the monofilament score (p < 0.001), suggesting reduction in ability to detect external forces. All center of pressure parameters increased significantly while wearing thick socks (p < 0.017), implying reduction of postural stability. They then decreased significantly with the additional use of insoles (p < 0.017).

    Conclusion: Previous studies have documented the changes in plantar pressure distribution with the use of orthopedic insoles. This study further suggests that such changes in contact mechanics could produce some balance-improving effects, which appears not to have been reported earlier.

    Clinical relevance: Wearing thick socks reduces plantar pressure sensitivity and increases postural sway which may increase risk of falls. Orthopedic insoles and footwear with similar design could potentially be a cost-effective method in maintaining postural balance when wearing thick socks. 

  • 15.
    Ma, Christina Zong-Hao
    et al.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Zheng, Yong-Ping
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Lee, Winson C.-C.
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Changes in gait and plantar foot loading upon using vibrotactile wearable biofeedback system in patients with stroke2018In: Topics in Stroke Rehabilitation, ISSN 1074-9357, E-ISSN 1945-5119, Vol. 25, no 1, p. 20-27Article in journal (Refereed)
    Abstract [en]

    Background: Patients with stroke walk with excessive foot inversion at the affected side, which may disturb their balance and gait.

    Objectives: This study aimed to investigate the effects of instant biofeedback of plantar force at the medial and lateral forefoot regions on gait and plantar foot loading in patients with stroke.

    Methods: A total of eight patients with hemiplegic stroke, who had flexible rearfoot varus deformity at the affected side, participated in this study. A vibrotactile biofeedback system was developed and evaluated. It analyzed forces at the medial and lateral forefeet, and instantly provided vibration clues when the plantar force at medial forefoot was less than a threshold. Each subject’s three-dimensional gait parameters and plantar-pressure distribution during walking were measured under two experimental conditions (sequence randomized): with and without the device turned on (Trial-registration number: ChiCTR-IPB-15006530 and HKCTR-1853).

    Results: Providing biofeedback significantly reduced the foot inversion and increased the mid-stance foot–floor contact area and medial midfoot plantar pressure of the affected limb, bringing the values of these parameters closer to those of the unaffected side. The biofeedback also significantly reduced the unaffected side’s excessive knee flexion and hip abduction.

    Conclusions: There were signs of improved foot loading characteristics and gait upon provision of instant vibrotactile biofeedback of plantar force. The positive results of this study further support the development of wearable biofeedback devices for improving gait of patients with stroke. 

  • 16.
    Ma, Christina Zong-Hao
    et al.
    Jönköping University, School of Health and Welfare, HHJ. Prosthetics and Orthotics. Jönköping University, School of Health and Welfare, HHJ, Dep. of Rehabilitation. Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Zheng, Yong-Ping
    Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University.
    Lee, Winson Chiu-Chun
    School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong.
    Vibrotactile Wearable Biofeedback System Integrated with Force Sensors at Plantar Foot Could Relieve Foot Varus Deformity in Patients with Stroke2017Conference paper (Refereed)
    Abstract [en]

    BACKGROUNDPlantar sensory input is a crucial component of proprioceptive system, which is important for maintaining balance and gait control. Foot orthoses are traditionally prescribed to correct/compensate foot deformity and relieve foot pain in patients. Adding some electronic components at insoles to capture the plantar force information and providing corresponding feedback information could compensate sensory loss in patients and amputees [1-3], this may further be applied to help improve lower limb motor control.AIMTo investigate the effect of instant biofeedback of plantar pressure distribution at medial and lateral forefoot on alteration of foot inversion and push-off forces during stance phrase in patients with hemiplegic stroke.METHODThis study was conducted in a university locomotion laboratory. Convenience sampling approach was adopted to recruit 8 patients with hemiplegic stroke (7M+1F, age 54±10 years, height 175±6 cm, weight 72±11 kg) in this study. All participants walked with visible foot inversion and seven of them walked with visible foot plantarflexion in swing phrase. The foot inversion and plantarflexion deformities were flexible and can be corrected by external forces.A vibrotactile biofeedback system was developed and evaluated, which integrated two force sensors at plantar surface of foot in a pair of flat insoles measuring the plantar forces at medial and lateral forefoot, and wirelessly sent instant control signals to one vibrator at wrist when the magnitude of detected plantar force at medial-side forefoot was lower than 50% of the lateral-side’s.A three-dimensional motion capture system (3D) motion capture system (Vicon Nexus 1.8.1, Vicon NexusTM, Vicon Motion Systems Ltd., UK) and an in-shoe plantar pressure measurement system (novel pedar-x system, PedarTM, novel GmbH, Munich, DE) were used to measure each subject’s spatial-temporal gait parameters and plantar pressure distribution during walking in each of the two experimental conditions with randomized sequences: 1) with biofeedback system turned-off, and 2) with biofeedback system turned-on.RESULTSUpon turning on the biofeedback system, the medial-side plantar pressure at both forefoot and midfoot of the affected limb increased significantly and became close to that of the sound limb, while the plantar pressure at rearfoot and lateral-side midfoot of the affected limb decreased significantly in subjects (Figure 1, p<0.05). The subjects adjusted their gait pattern by significantly decreasing the foot external rotation and hip flexion, and increasing the pelvic backward rotation of both limbs during stance phrase (p<0.05). Although no significant difference was found, subject’s affected limb also revealed notable reduction of foot inversion in stance phrase and increase of plantar-flexion in terminal stance phrase during walking upon using the device.

    DISCUSSION & CONCLUSIONInstant vibrotactile biofeedback of plantar pressure distribution at medial and lateral forefoot helps relieve the foot inversion, facilitate initiation of swing phrase, and additionally increase weight-bearing symmetry in stance phrase during walking in patients with stroke. The positive results of this study shed new lights on future research of wearable plantar force-based biofeedback system for improving gait in people with impaired lower-limb motor control. It further allows the targeted gait training and improvement of motor control to be conducted in both indoor and outdoor environments.

  • 17.
    Ren, Long Jun
    et al.
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Wang, Li Ke
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Ma, Christina Zong-Hao
    Jönköping University, School of Health and Welfare, HHJ, Dep. of Rehabilitation. Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Yang, Ying Xin
    Department of Soft Tissue Injuries Center, General Hospital of Shenyang, P.R. China.
    Zheng, Yong Ping
    Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong.
    Effect of conventional physiotherapy on pain and muscle stiffness in patients with low back pain assessed by a wireless hand-held tissue ultrasound palpation system (TUPS)2019In: International Journal of Physical Medicine Rehabilitation, E-ISSN 2329-9096, Vol. 7, no 2, p. 1-5, article id 512Article in journal (Refereed)
    Abstract [en]

    Background: Low back pain (LPB) is a common health problem. While physiotherapy can relieve pain and the muscle stiffness of patients with LBP was shown to be different from healthy people, few studies have investigated the effect of physiotherapy on back muscle stiffness in patients with LBP.

    Objective: To investigate the effect of a 5-day conventional physiotherapy treatment on muscle stiffness of patients with LBP using a newly developed wireless hand-held ultrasound probe.

    Methods: A total of ten patients with LBP participated in this study. They received customized conventional physiotherapy containing electrical therapy, traditional Chinese medicine, manipulation and wax therapy. The pain level was evaluated by the visual analogue scale, and the muscle stiffness was measured by a wireless hand-held tissue ultrasound palpation system. The muscle stiffness of left and right sides at L1 and L4 levels and pain level were evaluated in two conditions, including baseline and 5-day post treatments.

    Results and discussion: After receiving the treatment, the muscle stiffness of all tested low back regions increased significantly (p=0.040). The muscle stiffness at L4 level was significantly higher than that of L1 level (p=0.021). No significant difference of muscle stiffness between left and right sides was found. The correlation between the muscle stiffness and VAS score appeared to decrease after receiving the treatment (R2 changed from 0.3598 to 0.0533).

    Conclusion: A five-day conventional physiotherapy treatment could relieve the pain level and increase the muscle stiffness of patients with LBP as evaluated by a wireless hand-held ultrasound probe. The stiffness of back muscle at L4 level was significantly higher than that of L1 level in patients with LBP. The treatment may change the correlation between the muscle stiffness and VAS score at low back region.

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  • 18.
    Wan, Anson H.
    et al.
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Wong, Duo W.
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Ma, Christina Zong-Hao
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Zhang, Ming
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Lee, Winson C.
    Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Wearable vibrotactile biofeedback device allowing identification of different floor conditions for lower-limb amputees2016In: Archives of Physical Medicine and Rehabilitation, ISSN 0003-9993, E-ISSN 1532-821X, Vol. 97, no 7, p. 1210-1213Article in journal (Refereed)
    Abstract [en]

    Objective: To evaluate a newly developed biofeedback device enabling lower-limb amputees to identify various floor conditions.

    Design: Self-control with repeated measures (with and without the biofeedback device) within the amputee group, and group control comparing between amputee and nonamputee groups.

    Setting: University locomotion laboratory.

    Participants: Five lower-limb amputees and 8 nonamputees (N=13).

    Interventions: A wearable biofeedback device, which identified different floor conditions by analyzing the force patterns under the prosthetic feet and provided vibration cues in response to different floor conditions, was provided to the amputees.

    Main Outcome Measures: The subjects stepped on a foam platform concealing a small object or no object at 1 of the 4 locations of the foot sole. Subjects were asked whether there was a small object under their feet and the location of the object if it existed. The test was repeated with 4 different object types and 4 object locations. The success rate of floor identification was evaluated.

    Results: Without the biofeedback device, nonamputee subjects (76.56%) identified floor conditions better than amputees (22.5%) significantly (P<.001). On using the biofeedback device, the amputees significantly improved (P<.01) their success rate showing no significant difference (P=.746) compared with the nonamputees. No significant differences were found among object types (P=.689).

    Conclusions: Amputees performed significantly worse than nonamputees in recognizing the different floor conditions used in this experiment. With the biofeedback device, amputees significantly improved their abilities in identifying different floor conditions. Future attempts could configure the device to allow it to provide warning signals in response to fall-inducing conditions.

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