Khang, Gon

Mammalian collagens have been used as a base material for collagen matrices in tissue engineering applications. However, collagens of aquatic animals and human sources can potentially be utilized as a safe and viable substitute, because collagen products of bovine origin have been shown to be contaminated with some diseases. In the present study, we prepared and investigated collagen materials from several sources (bovine skin, porcine skin, amniotic membrane and starfish) as matrix biomaterials

Photoacoustic imaging (PAI) is a non-invasive and<br> non-ionizing imaging modality that combines the absorption contrast<br> of light with ultrasound resolution. Laser is used to deposit optical<br> energy into a target (i.e., optical fluence). Consequently, the target<br> temperature rises, and then thermal expansion occurs that leads to<br> generating a PA signal. In general, most image reconstruction<br> algorithms for PAI assume uniform fluence within an imaging object.<br> However, it is k

This study was designed to investigate how the electrically-elicited tactile sensation is affected by different types of electrical stimulation in terms of the sensory activation threshold and sensation specificity. The experiments were conducted on 49 healthy subjects varying 1) the modulation type (pulse amplitude modulation and pulse width modulation), 2) the polarity (anodic and cathodic), and 3) the waveform (monophasic and biphasic). Our findings include that 1) the sensation became adapte

This study was aimed to characterize and investigate the feasibility of the electrically-elicited sensation as a sensory feedback technique. Two experiments were performed using a monophasic rectangular pulse train of which either the current or the frequency was modulated. The activation and pain thresholds, the discrimination ability and the description of the sensations were defined,measured and analyzed for ten healthy subjects. Diverse thresholds were acquired due to the individual differen

This study was designed to answer the following three questions: (1) is it possible to elicit tactile stimulations by applying electrical stimulation to the skin?, (2) if so, how are the sensations affected by the stimulus parameters, pulse frequency, pulse amplitude (current), pulse width, polarity, and inter-electrode distance?, and (3) what is the relationship between the nerve afferents and the tactile sensations? The rectangular monophasic pulse train was applied to the subject's fingerpad

The importance of scaffold biomaterials has greatly been emphasized in in vitro culture of tissue-engineered cartilage and threedimensional (3D) environment. The development of new materials which are able to enhance cellular differentiation is critically important for the future use of biomaterial scaffolds in tissue engineering and regenerative medicine. Here, we demonstrated the feasibility of alginate coating method of fibrin/HA composite gel as a novel trial for cartilage formation. Rabbit

This study was designed to investigate the feasibility to utilize the electromyogram (EMG) for estimating the muscle torque. The muscle torque estimation plays an important role in functional electrical stimulation because electrical stimulation causes muscles to fatigue much faster than voluntary contraction, and the stimulation intensity should then be modified to keep the muscle torque within the desired range. We employed the neural network method which was trained using the major EMG parame

The purpose of this study is to develop a minimally constraint joint angle measurement system for the feedback control of FES (functional electrical stimulation) locomotion. Feedback control is desirable for the efficient FES locomotion, however, the simple on-off control schemes are mainly used in clinic because the currently available angle measurement systems are heavily constraint or cosmetically poor. We designed a new angle measurement system consisting of a magnet and magnetic sensors loc

This study was designed to apply the stimulation system developed in our laboratory to investigate how the stimulation conditions affect the muscle contractile characteristics in the isometric condition as well as during the FES standing/walking. Four paraplegic and ten healthy subjects participated in this study, and their knee extensors were voluntary contracted or electrically stimulated to measure the muscle force and the fatigue index for different waveforms of the pulse train. We also inve

This study was designed to propose a feedback muscle force (or joint torque) control system for incompletely paralyzed patients whose muscle(s) was contracted by electrical stimulation and voluntary activation simultaneously. For this end, the joint torque needed to be monitored so as to adjust the electrical stimulation intensity accordingly. A new method named as the parallel filter algorithm was developed to separate the mixed electromyogram (MEMG) into the evoked electromyogram (EEMG) and vo

The purpose of this work is to develop the FES controller that can cope with the muscle fatigue which is one of the most important problems of current FES (Functional Electrical Stimulation). The feasibility of the proposed FES controller was evaluated by simulation. We used a fitness function to describe the effect of muscle fatigue and recovery process. The FES control system was developed based on the biological neuronal system. Specifically, we used PD (Proportional and Derivative) and GC (G

This study was designed to investigate the feasibility of utilizing an adaptation for selective elicitation of tactile sensations by means of transcutaneous electrical stimulation. We conducted the first experiment to investigate how the stimulation frequency affected the adaptation. Twenty healthy subjects participated in the second experiment to confirm our proposal that the perception intensity of the low-frequency vibration can be enhanced after a high-frequency adaptation, and vice versa. I

We proposed a transcutaneous electrical stimulation method to elicit pressure and vibration at any intended intensity and/or frequency. First, pressure and vibration were induced via a series of rectangular pulse trains delivered to the surface electrodes placed on the index finger pad of 46 healthy subjects in total. Load cells and coin motors were employed to quantify the perception intensity and frequency of the elicited sensations. We observed that the perception intensity and frequency were

This study was designed to develop a new algorithm to extract the voluntary EMG and the evoked EMG from a mixed EMG generated when the muscle is stimulated both voluntarily and by electrical stimulation in the FES system. The proposed parallel filter algorithm consists of three phases: (1) Fourier transform of the mixed EMG, (2) multiplication of the transformed signal to two frequency functions, and (3) inverse Fourier transform. Four incomplete spinal cord injured patients participated in the