Min-Chun Pan

Inertial Sensing Based Assessment Methods to Quantify the Effectiveness of Post-Stroke Rehabilitation

In clinical settings, traditional stroke rehabilitation evaluation methods are subjectively scored by occupational therapists, and the assessment results vary individually. To address this issue, this study aims to develop a stroke rehabilitation assessment system by using inertial measurement units. The inertial signals from the upper extremities were acquired, from which three quantitative indicators were extracted to reflect rehabilitation performance during stroke patients’ movement examination, i.e., shoulder flexion. Both healthy adults and stroke patients were recruited to correlate the proposed quantitative evaluation indices and traditional rehab assessment scales. Especially, as a unique feature of the study the weight for each of three evaluation indicators was estimated by the least squares method. The quantitative results demonstrate the proposed method accurately reflects patients’ recovery from pre-rehabilitation, and confirm the feasibility of applying inertial signals to evaluate rehab performance through feature extraction. The implemented assessment scheme appears to have the potential to overcome some shortcomings of traditional assessment methods and indicates rehab performance correctly.

NIR image reconstruction using a single-rotating-source/detector scanning device

The research aims at developing an NIR tomography system using a single rotating source/detector scanning device associated with an image reconstruction scheme. Several simulation results concerning the phantom with one, two or three targets are presented. Additionally, the developed system is validated by a hemoglobin phantom inserted by another different volume density one.

Wavelength optimization using available laser diodes in spectral near-infrared optical tomography

For employing optimized wavelengths, a near-infrared (NIR) tomographic imaging system with multiwavelengths in a continuous wave (CW) enables us to provide accurate information of chromophores. In this paper, we discuss wavelength optimization with a selection from commercial laser diodes. Through theoretical analysis, the residual norm (R) and the condition number (κ) represent the uniqueness of a matrix problem and the smooth singular-value distribution of each chromophore, respectively. The optimum wavelengths take place for large R and small κ. We considered a total of 38xa0wavelengths of laser diodes in the range of 633-980xa0nm commercially available to discover optimum sets for a broad range of chromophore combinations. In the 38xa0wavelengths, there exists 501,942 (C538), 2,760,681 (C638), and 12,620,256 (C738) combinations of five, six, and seven wavelength sets, respectively, for accurately estimating chromophores (HbO2, HbR, H2O, and lipids), water, lipids, and the scattering prefactor A. With the numerical calculation, the top 10xa0wavelength sets were selected based on the principle of large R and small κ. In the study, the chromophore concentration for young and elderly women are investigated; finally, choosing the laser diodes with a wavelength of 650, 690, 705, 730, 870/880, 915, and 937xa0nm is recommended either for young or elderly women to construct a spectral NIR tomographic imaging system in the CW domain. Simulated data were used to validate the claims.

NIR electro-optical measurement for pseudo-models of biological tissues

In the research, the pseudo-model technique is proposed and implemented to simulate biological tissues under the framework of investigating near infrared (NIR) light propagating in diffusive media. The same optical characteristics inhere in the corresponding pseudo-models as in real tissues, where pseudo-models are constructed by using various volume densities of Intralipid. The pseudo-model technique proposed in the study has following advantages: 1.For the NIR tomography imaging system, the output signal from the real tissue may be too weak to be detected beyond the ability of current technologies. Thus, the pseudo-model is a viable alternative to cope with the limitation of the system in the measurement of real tissues. 2.Once the pseudo-model of a real tissue is decided, its optical properties can be investigated thoroughly. In addition, the initial estimates for the reconstruction of NIR optical property images can be selected adequately, and the image reconstruction algorithm can be modified accordingly with the information acquired from the pseudo-model. In the experiment, a pseudo-model of the background with an inclusion is performed for real tissues of pork inserted by a bone. It is observed that 1 % v.d. and 3 % v.d. of Intralipids can replace the pork and the bone, respectively, and the characteristics of the pseudo-model proposed here are consistent with those of the real tissues. As part of conclusion, the use of the pseudo-model technique is a promising approach to mimicking real tissues, especially for some parts of human body unable to be detected effectively.

Focusing efficiency evaluation of ultrasonic energy for fabricated Fresnel lens through surface profile estimation and FEA

ABSTRACT High focusing efficiency of a multi-level Fresnel lens is desired when it is designed and fabricated. How to estimate the focusing efficiency is an important issue after the Fresnel lens is made. We propose a method to evaluate the focusing efficiency of the fabricated Fresnel lens based on its surface profile. The profile of Fresnel lens fabricated shows how similar to the designed, which has been theoretically predicted a maximal focusing efficiency such as 81% and 40.5% for a four-phase and two-phase level Fresnel lenses, respectively. This method can be applied to evaluate the focusing efficiency of any fabricated surface profile of Fresnel lenses prior to a direct experimental measurement for energy focusing. The focusing efficiency of a four-phase level Fresnel lens designed to operate at a frequency of 100 MHz of an ultrasonic ejector, which was fabricated by a two-mask process using SU-8 photoresist, approximate 60% is illustrated. Finite element analysis was employed to confirm and observe the energy focusing phenomenon of ultrasonic ejector models.

Design and verification of NIR DOT electro-optical measuring system

The study aims at developing a near infrared (NIR) tomography imaging system using a single rotating source/detector scanning device, which will be working for diffuse optical tomography (DOT) on medical applications. Some influential factors in terms of the design of this scanning device and test phantoms are investigated such as the temporal stability, air-absorption, container influence, and radiance normalization, etc. Then, a heterogeneous microsphere phantom with an off-center inclusion is investigated. It is observed that the radiance deviation between the heterogeneous and the homogenous is shifting with the inclusion position accordingly. Through the previously-mentioned system calibration, the back projection method as widely applied in the computed tomography (CT) technique is used to reconstruct optical images which indicate the distribution of optical property of the test phantom.