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Afzal, Muhammad Raheel,Eizad, Amre,Palo Peñ,a, Carlos Ernesto,Yoon, Jungwon Hindawi 2018 Journal of healthcare engineering Vol.2018 No.-
<P>Aging, injury, or ailments can contribute to impaired balance control and increase the risk of falling. Provision of light touch augments the sense of balance and can thus reduce the amount of body sway. In this study, a wearable reaction wheel-based system is used to deliver light touch-based balance biofeedback on the subject's back. The system can sense torso tilt and, using reaction wheels, generates light touch. A group of 7 healthy young individuals performed balance tasks under 12 trial combinations based on two conditions each of standing stance and surface types and three of biofeedback device status. Torso tilt data, collected from a waist-mounted smartphone during all the trials, were analyzed to determine the efficacy of the system. Provision of biofeedback by the device significantly reduced RMS of mediolateral (ML) trunk tilt (<I>p</I> < 0.05) and ML trunk acceleration (<I>p</I> < 0.05). Repeated measures ANOVA revealed significant interaction between stance and surface on reduction in RMS of ML trunk tilt, AP trunk tilt, ML trunk acceleration, and AP trunk acceleration. The device shows promise for further applications such as virtual reality interaction and gait rehabilitation.</P>
Afzal, Muhammad Raheel,Oh, Min-Kyun,Lee, Chang-Hee,Park, Young Sook,Yoon, Jungwon Hindawi Publishing Corporation 2015 BioMed research international Vol.2015 No.-
<P>Gait asymmetry caused by hemiparesis results in reduced gait efficiency and reduced activity levels. In this paper, a portable rehabilitation device is proposed that can serve as a tool in diagnosing gait abnormalities in individuals with stroke and has the capability of providing vibration feedback to help compensate for the asymmetric gait. Force-sensitive resistor (FSR) based insoles are used to detect ground contact and estimate stance time. A controller (Arduino) provides different vibration feedback based on the gait phase measurement. It also allows wireless interaction with a personal computer (PC) workstation using the XBee transceiver module, featuring data logging capabilities for subsequent analysis. Walking trials conducted with healthy young subjects allowed us to observe that the system can influence abnormality in the gait. The results of trials showed that a vibration cue based on temporal information was more effective than intensity information. With clinical experiments conducted for individuals with stroke, significant improvement in gait symmetry was observed with minimal disturbance caused to the balance and gait speed as an effect of the biofeedback. Future studies of the long-term rehabilitation effects of the proposed system and further improvements to the system will result in an inexpensive, easy-to-use, and effective rehabilitation device.</P>
Comparative analysis of switched inductor-based quasi-Z-source inverters
Afzal, Raheel,Tang, Yu,Song, Yinghao The Korean Institute of Power Electronics 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.10
A switched-inductor quasi-Z-source inverter (SI-qZSI) exhibits a higher gain than a quasi-Z-source inverter (qZSI) while keeping continuous input current. Like renewable power generation systems that result in low input voltage, SI-qZSI exhibits boosting ability that may not be adequate in some cases. A voltage-lifting unit can be formed by alternating one of the diodes in the switch inductor unit. A high step-up topology, such as qZSI with voltage-lifting unit (qZSI-VL), can be derived. The boosting factor of qZSI-VL can be enhanced further by retaining all the merits of the SI-qZSI. The overall conduction loss can be reduced under the same output and input voltage for the qZSI-VL, thereby enhancing efciency. In this study, the analysis of the qZSI-VL and its operating principle are explained. The characteristic comparison of qZSI-VL with the SI-qZSI and qZSI is discussed in detail. Finally, the prototypes of qZSI-VL and SI-qZSI are designed in the lab. Simulation and experiments are performed to verify the analysis.
Design of a Haptic Cane for Walking Stability and Rehabilitation
Muhammad Raheel Afzal,Irfan Hussain,Yasir Jan,Jungwon Yoon 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
Rehabilitation is suggested to be achieved by natural walk, and it may require assistive devices. Assistance provided should motivate the patient to use his own muscle strength rather than be dependent upon the device. Therefore, the devices should only provide minimum support required for the safety, stability, confidence building and guidance. These can be achieved with light touch cue provided at the patient’s hands. The proposed haptic cane design has an active haptic handle that can give light touch cue depending upon the body orientation sensed through smartphone. The active haptic handle can be manipulated by a Pantograph mechanism. The Pantograph and arm support’s positions and orientation are adjustable. The handle and arm support are mounted on the cane having a single wheel, coupled with motor, shaft encoder and an active brake, for achieving a controlled movement. The proposed design will be able to provide rehabilitation and postural stability for the patients.
Muhammad Raheel Afzal,Carlos Ernesto Palo Pena,Jungwon Yoon 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10
Reaction Wheels (RW) have traditionally been used in spacecraft to control their attitude. This paper presents a novel application of RW to deliver kinesthetic cues for balance training through the development of a wearable device that can deliver kinesthetic cues alike light touch. A prototype wearable device has been designed that has 4 RWs as main actuators to generate kinesthetic cues, and additionally the system includes a wireless interface to a computer for evaluation purposes. Two modes of controlling the device output were implemented, PID and Saturated PID (S.PID). For experimental verification, seven young healthy participants performed several balance tasks. The results thus obtained indicate significant (P<0.05) difference in participant’s Mediolateral (ML) trunk sway between experiments conducted without and with kinesthetic cues, and differences in ML trunk sway between PID and S.PID control modes. Thus the relatively small torques delivered by RWs of the proposed device can provide kinesthetic cues for balance assistance.
Raheel Ahmad,Ghulam Destgeer,Muhammad Afzal,Husnain Ahmed,Jin Ho Jung,Jinsoo Park,Kwangseok Park,Hyung Jin Sung 한국가시화정보학회 2017 한국가시화정보학회 학술발표대회 논문집 Vol.2017 No.5
We designed a robust bio-chemo-mechanical hybrid system capable to capture and separate specific target molecules. The system composed of aptamer15 modified streptavidin-coated polystyrene microsphere (PSMs-apt15) and acoustofluidic device to show non-destructive target molecule separation. In this study, thrombin is selected as target molecule. First, the thrombin was captured by target-specific aptamer15 functionalized on PSMs (PSMs-apt15-thrombin) from a mixture of protein solution and separated with acoustofluidic device which consist of single-layered starting polydimethylsiloxane (PDMS) microchannel with interdigital transducer (IDT) patterned on lithium niobate (LiNbO3) substrate to produce high frequency (130 MHz) travelling surface acoustic waves (TSAWs). Once the IDT was actuated, the thrombin captured complex (PSMs-apt15-thrombin) were separated from the proteins solution due to the vertical component of acoustic radiation force, as >1 for green fluorescent microsphere and collected at outlet 2 by sheath focusing, while other proteins solution with some unbound thrombin passed through outlet 1. This hybrid system based on TSAWs could greatly enable the separation of various low abundant protein biomarkers.
Acoustic Wave-Driven Functionalized Particles for Aptamer-Based Target Biomolecule Separation
Ahmad, Raheel,Destgeer, Ghulam,Afzal, Muhammad,Park, Jinsoo,Ahmed, Husnain,Jung, Jin Ho,Park, Kwangseok,Yoon, Tae-Sung,Sung, Hyung Jin American Chemical Society 2017 ANALYTICAL CHEMISTRY - Vol.89 No.24
<P>We developed a hybrid microfluidic device that utilized acoustic waves to drive functionalized microparticles inside a continuous flow microchannel and to separate particle-conjugated target proteins from a complex fluid. The acoustofluidic device is composed of an interdigitated transducer that produces high-frequency surface acoustic waves (SAW) and a polydimethylsiloxane (PDMS) microfluidic channel. The SAW interacted with the sample fluid inside the microchannel and deflected particles from their original streamlines to achieve separation. Streptavidin-functionalized polystyrene (PS) microparticles were used to capture aptamer (single-stranded DNA) labeled at one end with a biotin molecule. The free end of the customized aptamer15 (apt15), which was attached to the microparticles via streptavidin–biotin linkage to form the PS–apt15 conjugate, was used to capture the model target protein, thrombin (th), by binding at exosite I to form the PS–apt15–th complex. We demonstrated that the PS–apt15 conjugate selectively captured thrombin molecules in a complex fluid. After the PS–apt15–th complex was formed, the sample fluid was pumped through a PDMS microchannel along with two buffer sheath flows that hydrodynamically focused the sample flow prior to SAW exposure for PS–apt15–th separation from the non-target proteins. We successfully separated thrombin from mCardinal2 and human serum using the proposed acoustofluidic device.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2017/ancham.2017.89.issue-24/acs.analchem.7b03474/production/images/medium/ac-2017-03474b_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac7b03474'>ACS Electronic Supporting Info</A></P>