Tse-Yi Tu

A new non-invasive cuff-less blood pressure sensor

A non-invasive, cuff-less, capable of continuous detection and low cost blood pressure sensor is proposed in this study. The proposed blood pressure sensor has a specially-designed strain sensor attached to a flexible plate and encapsulated by a gel module. The sensor is able to detect pulse signals of the artery vibration under the skin of a human wrist by a simple, flexible attachment pad. The strain sensor is expected to vibrate in a synchronized fashion with artery pulsation. The pulse vibration is expected to be transmitted to the strain sensor through the gel module. This module is made of highly bio-compatible materials like polyethylene (PE), polyurethane (PU), polytetrafluoroethylene (PTFE), polydimethylsiloxane (PDMS), or polymethylmethacrylate (PMMA). The gel module supports the strain sensor to a stability condition with top surface contacting tightly with the human skin while the bottom surface is under a low pressure exerted by a pressurizing wrist belt.

Fuzzy control design of a magnetically actuated optical image stabilizer with hysteresis compensation

A fuzzy controller (FC) is designed for a magnetically actuated optical image stabilizer (OIS) in order to suppress the vibrations caused by hand shakings and hysteresis. To this end, the dynamic model of the OIS with consideration of hysteresis is first established, along with assuming the hand-shaking vibration as sinusoidal excitations. It is clearly shown that with capability of continuing parameter tuning, the FC is superior to the conventional PID for vibration suppression.

Optimizing a new blood pressure sensor for maximum performance based on finite element model

A new non-invasive, cuff-less, low-cost blood pressure (BP) sensor capable of continuous detection is optimized by this study for maximum performance. This blood pressure sensor module encapsulates specially-designed electrodes as a strain sensor to be attached to a flexible plate. In operations, the strain sensor is held stable with top surface contacting tightly with the human skin while the bottom surface under a low pressure exerted by a pressurizing wrist belt. The electrodes and plate are expected to vibrate in a synchronized fashion with artery pulsations as vibrations transmitted to the sensor through the module to vary the net (average) strain of electrodes, thus also varying its resistance. Employing a readout circuit of Wheatstone bridge, an amplifier, a filter, and a digital signal processor, the artery pulsations could be successfully converted to temporal voltage variations for calculating blood pressures via known algorithms. However, due to the small diameter of the artery, around 3 mm, mis-positioning (MP) of the sensor electrode area relative to the artery beneath is inevitable, which may lower sensor sensitivity due to smaller average strains. To remedy the problem, efforts are paid to conduct finite element modeling (FEM) and simulations on the electrodes, sensor module and the wrist including bone, tissue and other bio-structures to predict sensor output variations with respect to varied mis-positionings. Based on the predictions, the sensor optimal length is successfully found as 5 mm, which maximizes average strain, the sensitivity of the sensor.

A new cuffless optical sensor for blood pressure measuring with self-adaptive signal processing

A new cuffless, wireless optical blood pressure (BP) sensor is successfully developed by this study. This device employs the technique of photoplethysmograph (PPG) to read out in real time the intravascular blood volume change and then to calculate BP. The system utilizes a red-light LED with a wavelengths of 660 nm. The readout circuit includes a pre-amplifier, a band-pass filter, a programmable gain amplifier (PGA), an Arduino unit for calculation and a Bluetooth module for wireless communication. A notebook or a mobile phone is also used to display continuous BPs and conducts statistical analysis/results. The passband is from 0.3 to 3.4 Hz. The range of adjustable gain are from 60 to 80 dB. Measured PPGs of different subjects can be auto-adjusted with varied gain by a PGA with a pre-designed digital circuit. In results, the signal-to-noise ratio (SNR) is improved for accurate estimates on BPs. 8 subjects participated in the experimental validation, in which the obtained BPs are compared with the results from a commercial blood pressure monitor by OMRON. The maximum error of experimental results is ± 6 mmHg, which is less than 8 mmHg conforming to the requirement by the Advancement of Medical Instrumentation (AAMI). This study pioneers to report stable, accurate estimates on BPs by a cuffless optical hand-held device.

A new readout circuit for a high resolution portable blood pressure sensing system

A new front end readout circuit for non-invasive, cuff-less, convenient blood pressure sensor is proposed in this study. The blood pressure sensor features continuous detection, low power and low cost. The sensor is able to detect pulse signals of the artery vibration under the skin of a human wrist. The front end circuit consists of a sensing circuit, an amplification, a peak-sensing circuit and a counter. The designed circuit is accomplished by Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 µ m 1P6M 1.8V mixed - signal CMOS process. The proposed chips with the die area of 1.35×1.13mm2 and 1.37×1.37mm2 are fabricated by National Applied Study Laboratories National Chip Implementation Center (NARL NCIC). The front-end readout IC is simulated and experimented. The pulsation amplitude in terms of output voltage of readout circuit is successful to a satisfactory accuracy of the BP sensor to be within 5 mmHg, lower than 8 mmHg, a standard by Association for the Advancement of Medical Instrumentation (AAMI).

Effects of Mis-Positioning a New Cuffless Blood Pressure Sensor and Optimal Design via a 3D Fluid-Solid-Electric Finite Element Model

The effects of mis-positioning a newly-designed noninvasive, cuffless blood pressure sensor are thoroughly investigated via simulation and analysis on a 3D fluid-solid-electric finite element model. A subsequent optimal design of this blood pressure is conducted based on the aforementioned mis-positioning effects. A highly-accurate, non-invasive, cuffless blood pressure (BP) sensor was successfully developed recently for an effective personal monitoring device on blood pressures. This new small-sized, portable blood pressure sensor is able to offer continuous BP measurements. The availability of continuous blood pressures are important for monitoring and evaluating personal cardiovascular systems. The sensor contains a strain-sensitive electrode encapsulated by flexible polymer. As the sensor placed on the position right on the top of the center of the wrist pulsation area, the deflection of the sensor induces the resistance changes of the electrode. By measuring the changes in electrode resistance, the level of pulsation is successfully quantified. Subsequent calculation based in this measurement can lead to fair estimates on blood pressures.However, as the sensor is placed on the wrist area where pulsation occurs, the mis-positioning of the sensor to the desired location, the center of the pulsation area, is inevitable. This study is dedicated to investigate the effects of the mis-positioning via a 3D finite element model. A new 3D fluid-solid-electro coupling interaction finite element model of the wrist is built for predicting the vibration of radial artery and then diastolic and systolic blood pressures. The FEM includes sensor of gel capsule and strain-sensing electrodes, radial artery, blood, radius bones, tendon, muscles and the front-end readout circuit. The FEM is the multi physics FEM with fluid, solid and electric. The section of wrist is constructed from magnetic resonance imaging (MRI) and the length of the FEM is 40mm. The complete 3D FEM model successfully simulated the vibration of skin surface and the sensor module. The diastolic and systolic blood pressures can be accurately predicted by the simulated output resistance.The pulsation levels due to varied mis-positionings are simulated by the built model, and simulation results are successfully validated by experiments. It is found that due to the unsymmetrical geometry of the wrist, the pulsation levels are also varied in an un-symmetric fashion with the mis-positionings in different directions. The maximum output of the BP sensor occurs when the sensor is placed ±3 mm away from the center of the pulsation area, while the sensor output remain valid for subsequent signal processing as the sensor is placed within ±5 mm from the pulsation center. Considering the inevitable mis-positionings by all possible users in different genders and ages, the sizes of the sensors are successfully optimized for satisfactory average signal quality over all possible users.Copyright

OPTIMAL DESIGN AND EXPERIMENTAL VALIDATION OF A NEW NO-CUFF BLOOD PRESSURE SENSOR BASED ON A NEW FINITE ELEMENT MODEL

A new multi-physics finite element model (FEM) on the vibration of the radial artery on the wrist is built by this study to predict vibration of wrist artery vessel vibration and then diastolic and systolic blood pressures. The FEM includes the sensor of gel capsule and strain-sensing electrodes, skin, bones and muscles. The vibrations of skin surface and the sensor module are successfully simulated by the established FEM. The resulted vibratory deformation of the sensor electrodes are further transformed to resistance variations to mimic realistic electronics of the front-end readout circuit via establishing a cross-discipline sub-FEM model. The established FEM can is particularly customized to varied ages, weights, heights, genders, and special cardiovascular diseases of users. The customization can be performed in a fashion of one-time calibration by medical staff and/or medical staff. With the customized FEM in high accuracy level, the diastolic and systolic pressures can be accurately predicted by the simulated output resistance variation. Based on simulation FEMs, the design of the pulse sensor is successfully optimized via the processes of Taguchi and numerical methods. The measurements are also conducted to a dozen of subjects. It shows that the designed novel blood pressure sensor is capable of sensing the blood pressure to require accuracy level of the error less than 10% as compared to commercial counterparts with a cumbersome cuff.Copyright

An LCL-Lens Array with Electrodes of Interlaced Structure in Applications of Auto-Stereoscopic

Commercial auto-stereoscopic display systems have equipped optical lenticular lens sheets in order to realize the function which is able to support two images or views to right and left eyes of viewers. In applications of auto-stereoscopic display, the method of using the lenticular lens sheet, also called time- or spatial-multiplexed method, is first proposed as a patent by Ichinose [1]. The method has more advantages, which includes high luminous performance, movable of eyes position with constant view distance and watchable of multi-viewer. Besides, it can be also easily manufactured to make it very popular. Owing to the superiority, some studies about lenticular lens sheets have been proposed. Berkel et al. [2] have proposed several researches about the method of using lenticular lens sheets on multi-view auto-stereoscopic displays, and he has also proposed that slanted lenticular lens sheets or pixels could be improved the effect of flipped image by boundaries of lens and pixel [3–5]. 2D/3D switchable display is first realized by a method of dual-lenticular lens sheets [6]. Moreover, the method of using lenticular lens sheets has been proposed to be replaced by liquid crystal, LC, lens arrays, [7–9] in order to control viewer distance based on a function of tunable focal length. For the method, some issues of LC lenses should be solved like non-smooth potential in the LC layer and to improve the lens power [10–12].Copyright