Bor-Wen Yang

Full-color skin imaging using RGB LED and floating lens in optical coherence tomography

The cosmetic industry has witnessed significant growth in recent years. Conventional hand-held skin cameras allow for 2D inspection of the skin surface. This paper proposes a new model for full-color 3D imaging of the skin tissue using fiber-based optical coherence tomography (OCT). Compared to laser or LD sources, RGB LED was found more suitable and thus chosen in the low-coherence interferometry due to its wider bandwidth. A floating objective lens was used to confocalize the R, G and B imaging planes and to derive a full-color image of the capillary system in the skin tissue. The skin imaging system can be miniaturized to form a new hand-held model using an RGB integrated source, a micro-interferometer module and a high-speed beam steering device. Non-invasive, full-color and hand-held skin imaging contributes to advances in the fields of skin science, dermatology and cosmetology.

Measuring micro-interactions between coagulating red blood cells using optical tweezers

Agents that alter the dynamics of hemostasis form an important part in management of conditions such as atherosclerosis, cerebrovascular disease, and bleeding diatheses. In this study, we explored the effects of heparin and tranexamic acid on the efficiency of blood coagulation. Using optical tweezers, we evaluated the pN-range micro-interaction between coagulating red blood cells (RBCs) by measuring the minimum power required to trap them. By observing the mobility of RBCs and the intensity of cellular interactions, we found that the coagulation process can be separated into three phases. The effects of heparin and tranexamic acid were examined by observing variations in cellular interaction during the coagulation phases. Heparin attenuated the interaction between RBCs and prolonged the first phase whereas the samples containing tranexamic acid bypassed the first two phases and immediately proceeded to the final one.

The evaluation of interaction between red blood cells in blood coagulation by optical tweezers.

To maintain the life of patients with hemophilia, apoplexy or hemorrhage, appropriate blood coagulation is crucial. To study the microscopic phenomena of blood coagulation and the therapeutic effects of blood medication, optical tweezers were applied to estimate the interaction between red blood cells in the coagulation process. By measuring minimum optical power required to trap the coagulating blood cells, the pN-scale interaction between them can be evaluated. In normal blood sample, the interaction rises in accordance with coagulation time. The addition of heparin attenuates the interaction and postpones the coagulation, whereas the addition of tranexamic acid starts the coagulation early at the beginning and allows the process completed in less time.

Applying RGB LED in full-field optical coherence tomography for real-time full-color tissue imaging

A conventional handheld skin camera is suitable for 2D inspection of shallow skin. Due to its high resolution and noninvasiveness, optical coherence tomography (OCT) has become a popular medical-imaging technology. Among OCT schemes, full-field optical coherence tomography (FF-OCT) is suitable for rapid en face imaging, as it uses a 2D imaging device for pixel processing of a sample plane. Because of its wide bandwidth and long lifetime, an RGB LED was chosen in an FF-OCT system among three source candidates in this study. A full-color tissue image and real-time video were obtained from the system to demonstrate the potential of the RGB LED FF-OCT system in medical imaging. All devices used here can be integrated by micro-optoelectromechanical technology into a handheld model. Noninvasive, real-time, full-color handheld imaging capability contributes to advance dermatology and cosmetology.

Heat stress exposing performance of deep-nano HK/MG nMOSFETs using DPN or PDA treatment

Abstract Decoupled plasma nitridation (DPN) or post-deposition annealing (PDA) process after high-k (HK) deposition to repair the bulk traps or the oxygen vacancy in gate dielectric is an impressive choice to raise up the device performance. Before heat stress, the electrical performance in drive current, channel mobility and subthreshold swing with both treatments was approximate, except the higher annealing atmosphere causing the thicker interfacial layer and reducing the overall related dielectric constant. After temperature stress, the electrical performance for all of the tested devices was slightly deteriorated. The degradation degree for electrical performance with PDA treatment group was the worst case due to NH3 atmosphere forming Si–H bond on the channel surface, which was broken after stress and produced more interface state reflected with the increase of subthreshold swing.

Modification of Early Effect for 28-nm nMOSFETs Deposited With HfZrO x Dielectric After DPN Process Accompanying Nitrogen Concentrations

The model of the Early effect at nanonode devices should be modified owing to the unignored contribution of vertical gate field. This effect is more obvious when the channel length is decreased more. Using higher decoupled plasma nitridation nitrogen treatment after high-k dielectric deposition, besides enhancing the drive current due to promoting the microscopic homogeneity of the Hf-based film, seems also to little suppress the Early effect. This phenomenon at L = 0.03 μm device is proved and due to the lower β-slope of influencing the high-vertical field.

Exploring the microscopic mechanism how electromagnetic radiation affects blood coagulation process

In this study, we explored the mechanism of how modulated radiation affects blood coagulation by measuring the intercellular interactions among red blood cells (RBCs) during the coagulation process. Using optical tweezers, we evaluated the pN-range micro-interactions between coagulating RBCs by determining the power required to trap them. By deriving the coagulation curve of the cellular interactions versus coagulation time, we discovered three distinct phases of the human coagulation process. We discovered that depending on the position of infrared radiation relative to the coagulating RBCs, a mechanism induced by electromagnetic radiation could promote or suppress the blood coagulation by either enhancing or attenuating the interactions among coagulating RBCs during the coagulation process. Additionally, we found that extremely low frequency-modulated radiation was able to induce resonant oscillation of the coagulating RBCs, which could moderate the impact of electromagnetic radiation on blood coagulation.

Electromagnetic effects of non-ionizing radiation on a cell nucleus and cell assembly

Electromagnetic radiation can be classified into ionizing and non-ionizing varieties. In this study, we designed two-beam optical tweezers to demonstrate that non-ionizing radiation could induce intercellular attraction between human red blood cells by its electromagnetic nature. An infrared spot in the optical tweezers was irradiated on an assembly of RBCs to polarize them and derived attractive interaction; the other visible spot was used to gauge the sub-pN intercellular interaction. It was found that 34~57 μW/μm2 IR radiation could cause attraction among a 3~4 RBC cluster; the power density was equivalent to only 10-3~10-2 of that used in a CD drive. We found that the intercellular interaction was approximately proportional to the power density of the IR radiation. Besides, we observed 36 minutes of 75 μW/μm2 IR radiation could shrink the nucleus of an onion cuticle cell. Based on these results, we established a model to describe the electromagnetic effect of non-ionizing radiation on a cell assembly by inducing the micro-stresses transverse to its propagation axis.

Exploring a photo-acousto-optic effect for noncontacting photoacoustic sensing.

To avoid the use of ultrasound transducers and coupling gel in photoacoustic microscopy (PAM), we propose photo-acousto-optic tomography (PAOT) for noncontact photoacoustic (PA) sensing. The process consists of two parts. The first portion is the same as typical PAM, which employs a pulsed laser to induce acoustic waves. The difference from typical methods lies in the second part of the process, which applies a DC beam, rather than a conventional transducer, to sense the PA signal. A two-beam optical microscope system was designed to verify the PAOT effect, whereby an AC spot acted as the source to induce a PA signal, while a DC beam is applied to induce the acousto-optic effect for detection of the acoustic wave. We demonstrated the preliminary result that 5-100 Hz AC radiation could derive PA waves in a water-like medium along with detection sensitivity as high as 4.9%-10.0%; besides, the signal waveform could be detected by a DC spot 10-100 μm away for noncontact sensing with detection sensitivity of about 3.7%-10.4%. Without the need for a transducer or coupling gel, PAOT has the potential to modify conventional PAM into a pure optical system, which could make PA imaging more promising in practical applications.

The design of an achromatic two dimensional deflection prism

An achromatic two dimensional deflection prism was designed for applications of autostereoscopic or multi-view projection display systems. The relation between the beam deflection and the wedges was analyzed theoretically. The dispersion free condition and the determination of the biprism wedge were discussed in detail.