Design of a finger base-type pulse oximeter.

A pulse oximeter is a common medical instrument used for noninvasively monitoring arterial oxygen saturation (SpO2). Currently, the fingertip-type pulse oximeter is the prevalent type of pulse oximeter used. However, it is inconvenient for long-term monitoring, such as that under motion. In this study, a wearable and wireless finger base-type pulse oximeter was designed and implemented using the tissue optical simulation technique and the Monte Carlo method. The results revealed that a design involving placing the light source at 135°-165° and placing the detector at 75°-90° or 90°-105° yields the optimal conditions for measuring SpO2. Finally, the wearable and wireless finger base-type pulse oximeter was implemented and compared with the commercial fingertip-type pulse oximeter. The experimental results showed that the proposed optimal finger base-type pulse oximeter design can facilitate precise SpO2 measurement.

Speckle reduction by combination of digital filter and optical suppression in a modified Gerchberg-Saxton algorithm computer-generated hologram.

A speckleless illuminated modified-Gerchberg-Saxton-algorithm-type computer-generated hologram, which adopts a lower frequency of the iterative algorithm and calculation time, is proposed to code a hologram with two signals and position a multiplexing phase-only function, which can reconstruct the left and the right viewing holograms on the pupillary-distance position after the decryption and still maintain the content with high contrast and definition. The reconstructed image quality presents root mean square error of 0.03, with a diffraction efficiency of 87%, and signal-to-noise ratio of 8 dB after the analysis. Furthermore, two denoising techniques for the digital filter and optical suppression are combined, in which the speckle suppression with pseudorandom phase modulation and a rotating diffuser are utilized for successfully reducing the speckle contrast, which was reduced to below 4%. The goal was to reduce visual fatigue for the viewers.

Novel wearable and wireless ring-type pulse oximeter with multi-detectors.

The pulse oximeter is a popular instrument to monitor the arterial oxygen saturation (SPO2). Although a fingertip-type pulse oximeter is the mainstream one on the market at present, it is still inconvenient for long-term monitoring, in particular, with respect to motion. Therefore, the development of a wearable pulse oximeter, such as a finger base-type pulse oximeter, can effectively solve the above issue. However, the tissue structure of the finger base is complex, and there is lack of detailed information on the effect of the light source and detector placement on measuring SPO2. In this study, the practicability of a ring-type pulse oximeter with a multi-detector was investigated by optical human tissue simulation. The optimal design of a ring-type pulse oximeter that can provide the best efficiency of measuring SPO2 was discussed. The efficiency of ring-type pulse oximeters with a single detector and a multi-detector was also discussed. Finally, a wearable and wireless ring-type pulse oximeter was also implemented to validate the simulation results and was compared with the commercial fingertip-type pulse oximeter.

Novel noninvasive approach for detecting arteriovenous fistula stenosis.

Hemodialysis is the most common treatment for patients with end-stage renal disease. For hemodialysis, consistently functional vascular access must be surgically created with an anastomosis of artery and vein, referred to as an arteriovenous fistula (AVF). However, AVF dysfunction may occur over time. Angiography and Doppler ultrasound are usually used to detect the flow or the diameter of the AVF. But they require well-trained operators and are expensive, and even angiography is invasive. In this study, a noninvasive approach based on stethoscope auscultation for monitoring AVF stenosis was proposed. Here, a wireless blood flow sound recorder was designed to record blood flow sounds wirelessly. In order to effectively extract the varying feature of blood flow sounds for AVF stenosis, the 2-D feature pattern built from S-transform was also proposed as the feature in the AVF stenosis detecting algorithm. Different from other frequency-related coefficients, the feature pattern can contain the information of blood flow sounds in time and frequency domains simultaneously. Preliminary findings showed that the proposed approach can provide high-quality estimation of AVF stenosis (positive predictive value = 87.84% and sensitivity = 89.24%).

Pulfrich autostereo display with micro-prism array.

A micro-prism film, with spectral characteristics, is attached on a display panel to show images appearing with + 10° ~ + 50° and -10° ~-50° bright regions and with a + 10° ~-10° dark region. When both eyes separately receive the bright region and the dark region of an image, interocular delay would appear to generate a stereo perception. With the optical simulation software, LightTools 7.3.0, to simulate the brightness change, the light with lower brightness appears on the 0° region and the light with the highest brightness appears on the ± 10° region. The optimal viewing distance of 25 cm could accurately deliver the image with shading parallax to both eyes. The actual measurement of brightness presents the shading distribution, achieving the condition of binocular retinal illumination, and the angle of visibility appears on the ± 50° region, causing interocular delay so that the viewer generates the stereo perception.

Panoramic stereo photography based on single-lens with a double-symmetric prism.

Different from traditional panorama stereo acquisition technique shooting with numerous cameras, this study equips a double-symmetric prism in front of a single-lens camera to acquire images from four different angles of view, and the images acquired from the cameras every 20 degrees complete a pair of panorama stereo images with vertical angle of view ( ± 16 degrees) by image-based rendering. The panorama stereo acquisition technique reduces the number of cameras by three-fourth, and the acquired images contain vertical angles of view. Moreover, the image resolution is enhanced several times of the resolution of integral photography without moiré effect.

The influence of electro-acupuncture stimulation to female constipation patients.

This study aims to examine electro-acupuncture stimulation (EA) assisted therapy with analysis of heart rate variability to understand autonomic nervous activity variability (ANAV) and to track the changes in female patients with constipation. The average ages were 42 ± 12 years old. The participants were divided by a single-blind and randomized trial into two groups: the electro-acupuncture-point group, and the non-electro-acupuncture-point group. Both of the groups had eight treatments, once a week. For the electro-acupuncture (EA) group, needles were inserted into their Zusunli (ST36), Shangiuxu (ST37), Tiensu (ST25), Shueidao (ST28), Guanyuan (CV4) and Qihai (CV6) points. For the sham electro-acupuncture (SA) group, needles were inserted into acu-points that were not the ones mentioned for the EA group. While inserting needles, needles were inserted lightly into the participants' skin and removed quickly (mock Transcutaneous Electrical Nerve Stimulation, TENTS). After an eight-week treatment period, the autonomic nervous system activities of the SA group did not show significant differences in their heart rate variability. However, the autonomic nervous system activities of the EA group had continuously increased after each session. The normalized high frequency powers (nHFP) of their autonomic nervous system activities were 26.79 in the first week, and they increased to 32.28 in the fourth week. In the eighth week, their nHFP had increased to 37.60 (p < 0.05). The normalized low frequency power (nLFP) was 30.81 in the first week. However, it decreased to 25.98 after three weeks of treatment. After the eight-week treatment period, the nLFP decreased to 24.84 (p < 0.05). After the eight-week treatment, the control group did not appear to undergo any physiological change, while the constipation had been improved for the experimental group. It was found that the activation of parasympathetic nervous system in the experimental group increased after the eight-week treatment. The effects of such a result on the enhancement of the activation of parasympathetic nervous system and the improvement of constipation should be further discussed.

A hybrid temporal and spatial speckle-suppression method for laser displays.

We propose a system that reduces laser display speckles by vibrating the light pipe. A small displacement of the light pipe appears to allow the total reflection of the laser, thereby resulting in a homogenized speckle field that changes with time. In this case, the speckle interference generated by the pattern projected by the laser through the light pipe destroys the spatial homogenization of the laser beams when the light pipe is vibrated. Moreover, when the light pipe begins the sequential vibration, the phases and paths of the beams are changed after the beams traverse the light pipe. Consequently, temporal speckle wavefront superposition can homogenize the luminous intensity distribution of the speckle pattern. This process reduces the speckle contrast to less than 4% while maintaining a luminous intensity of greater than 70%.

Binary blazed grating based on autostereoscopic display mechanism.

The diffractive optical element blazed grating is proposed as the beam splitter for autostereoscopic displays in this study. With Lithographie Galvanoformung Abformung and inductively coupled plasma reactive-ion etching, a four-level blazed grating structure is produced. Moreover, highly translucent polydimethylsiloxane is transformed into symmetrical four-level blazed grating films. The experimental results show that the film can successfully transmit the left and the right images to the accurate positions, and the diffraction efficiency is 70.4% and the contrast ratio is above 80%, presenting the original stereoscopic image without it being affected by brightness and crosstalk. In the experiment of stereoscopic imaging, both the left and the right images could be clearly acquired, which proves the feasibility of blazed gratings as practical for the beam splitter of autostereoscopic displays.

Design of a symmetric blazed grating sheet embedded in an autostereoscopic display.

This study proposes a diffractive autostereoscopic display technology that utilizes blazed grating embedded in the liquid crystal panel to deliver a stereo image pair to both eyes. Having the diffractive red green blue beams as the color source of the panel, color filters are no longer required in this system. From the simulation analyses, not only could the brightness achieve 77.90%, but no serious chromatic aberration or cross talk appeared.

Variations of brain activities of acupuncture to TE5 of left hand in normal subjects.

This paper presents the evident effects of acupoint stimulation, using EEG (electroencephalogram) measurements. With acupuncture stimulation and the EEG measurement on the same meridian, EEG is able to accurately detect the effects of acupunctural point stimulation on brain waves. In this study, 24 subjects without heart or neural diseases were randomly separated into two groups of 12, named test and control groups. Similar procedures are performed; the subjects lay on a bed with eyes closed for ten minutes as the baseline. The test group received acupuncture at their Waiguan points (TE5) on their left hands for 20 minutes, while the control group did not. EEGs are recorded during pre-acupuncture, acupuncture stimulation and post-acupuncture stimulation periods. The EEG electrodes are at the T3, T4, O1 and O2 locations. Continuous wavelet transformation analysis is adopted; therefore, EEGs are divided into the following bands: δ (0.5-4HZ), θ (4-8HZ), α (8-13HZ) and ß (13-30HZ). During acupuncture stimulation, the θ energy is increased and had statistical differences at all electrode points, T3, T4, O1 and O2. Upon removing the needle, the energy at the T3 and T4 points slowly declined and revealed obvious statistical differences. During acupuncture, only α energy has been noted to have statistical difference and it was increased at the T3 point. However, the energy was decreased and had no statistical difference after five minutes. Acupuncture is proven to be able to affect brain waves, as the stimulation might have changed the tissues between the cranium and scalp; therefore, the brain waves are detected more easily.

Stereogram implemented with a holographic image splitter.

A special holographic optical element (HOE) which is used as an image splitter is developed to generate a stereogram on a 2.2-in. liquid crystal display panel. The special designed holographic optical element can be attached on the conventional panel directly to replace the traditional image splitter in a stereoscopic display panel. Experimental results show that two images corresponding to slightly different viewing angles displayed on a panel can be separated effectively and can be delivered to the right eye and left eye of an observer individually. The diffraction efficiency for individual right and left image in this developed holographic optical element is about 43%, and the contrast ratio of the diffracted images induced by cross talk is larger than 60%. Theoretical analyses show the proposed technique generates good contrast ratio and brightness performance for stereogram application.

Optics system design applying a micro-prism array of a single lens stereo image pair.

In this study we apply a micro-prism array technique to enable a single lens CCD to capture a stereo image for the simulation of double lens vision. A micro-prism array plate serves as the basis for design, which also improves the lightweight and portability of the overall system in addition to lowering the mass-production costs. Most important of all, this design possesses the characteristics of integration compatibility between general-purpose and video camera.