Yudong Luo

Development of a biomimetic non-invasive radial pulse sensor: Design, calibration, and applications

The research work aims at developing a real time non-invasive metabolism and blood circulation surveillance system for monitoring humans health condition by sensing the various bio-signals on human body. Our goal is to use the developed system to study the functions and characters of organs and tissues that highly relate with the metabolism and blood circulation system, also it is expected to help modeling the entire circulation system. At Phase I of the research, in this paper we focus on developing a new low-cost, portable, high accuracy, non-invasive radial pulse sensor. Inspired by touch capability and related biomechanical advantage of human fingertip, the mechanical design of the sensor mimics the physiological structure of human fingertip. The designed biomimetic sensor is well calibrated using a high-accuracy force sensor and the model is accurately identified by the system identification method. The calibrated sensor is then applied to diagnose the arterial stiffness by measuring the augmentation index (AI) which is the important biomarker of vascular aging. Preliminary results demonstrate the sensor performance that it is capable of non-invasively, accurately and reliably measuring radial pulse signals at real time, as well can be used to quantitatively determine the vessel aging.

Durable and cost-effective 3-D microforce sensor for musical tuning enhanced micro palpation of biological entities

This paper presents our development of highly sensitive and durable 3-D microforce sensors for our musical tuning enhanced in-vitro micro palpation system that will help to intuitively and interactively identify (by hearing) the mechanical signature or bio-marker of biological entities, including cells, embryos, tissues, and organs. During the implementation, the sensor serves as “tactile stethoscope” that be able to access the surface of biological entity and measures its mechanical properties and changes. These measurements are then converted into 88-key piano musical voices for hearing and identification in real time. Experimental results demonstrate the performance of the developed microforce sensors, as well successful preliminary in-vitro micro palpation on the fruit vesicles. Our development on the sensors is a major step towards a multimodal, intuitive, and interactive system engineering approach for biomedical studies such as cellular pathology, tissue engineering, plant and animal physiology.

Measurement and analysis of braille stimulus to brain using an EEG: A preliminary study

Braille systems currently available for blind and visually impaired (BVI) individuals are inadequate. Braille books and refreshable displays are large and hard to use during travel. For BVI individuals to truly have access to written materials wherever they are, a portable, adaptable, and user friendly device is needed. One way to achieve this is the use of an electronic stimulation to the fingertip rather than stimulation by mechanical pins actuated by complicate electromechanical mechanism. As the first step, this paper discusses preliminary investigations and findings of the brain signals observed during mechanical Braille stimulation in order to later correlate them with the brain signals observed during electronic Braille stimulation. The next step is to design a portable and adaptable electronic Braille device. The device will use brain signals induced by mechanical Braille stimulation as the control reference for achieving correlated and adaptable electronic Braille stimulation for users.

Enabling earthworm-like soft robot development using bioinspired IPMC-scissor lift actuation structures: Design, locomotion simulation and experimental validation

The paper parents our recent development on the earthworm-like soft robot. The robot is designed through combination of smart electro-active polymer (EAP) materials and the efficient expandable structure. The employed EAP material, called ionic polymer-metal composite (IPMC) that can directly provide the actuation to the expendable scissor-lift structure, so as to enable the robot to mimic locomotion mechanism of the earthworm. To reach the goal of the project, in this paper, we firstly developed a high performance IPMC driver for the IPMC actuators embedded in the mimicking robot system, and then based on the proposed three 2-D earthwormlike locomotion structures that consist of different complex forms of IPMC actuators and expendable lift-scissor structures, several peristaltic motion behavior simulations were conducted in order to compare the locomotion advantages of three designed soft robot structures. In addition, preliminary experimental results on one of designed structures are demonstrated and all simulation and experimental results validate the feasibility and effectiveness of our biomimetic design. Ongoing work is focusing on the dynamic modeling and control of the more segmented and dimensional earthworm-like robot using the designed actuation mechanism.

Finger-eye: A wearable text reading assistive system for the blind and visually impaired

This paper presents our recent research work in developing a portable and refreshable text reading system, called Finger-eye. In the system, a small camera is added to the fingertip-electrode interface of the current Electro-tactile Braille Display and placed on a blind persons finger to continuously process images using a developed rapid optical character recognition (OCR) method. This will allow translation of text to braille or audio with natural movement as if they were reading any Braille Display or book. The braille system that will be used is a portable electrical-based braille system that will eliminate the problems associated with refreshable mechanical braille displays. The goal of the research is to aid the blind and visually impaired (BVI) with a portable means to translate any text to braille, whether in the digital realm or physically, on any surface.

Developing a self-powered and directly digitized piezoelectric micro sensor for monitoring blood pressure change inside brain aneurysm after endovascular treatment: A feasibility study

Pathologies in blood vessels are categorized under two major classes: blockage and bleeding. Bleeding is mainly caused by aneurysm. The aneurysm can grow and become so thin that it leaks or ruptures, causing a subarachnoid hemorrhage (SAH). With the available endovascular treatment options, studies show that the post procedural complication rate is 3% leading to delayed bleeding. The reason behind this rupture is still unclear. One of the main theories behind this rupture is: no change in the pressure within the aneurysm. Our research aims at investigating this rupture problem by designing a wireless, self-powered, passively operated micro (<; 1cm) PolyVinyliDene Fluoride (PVDF) pressure sensor that can be deployed within the aneurysm, during flow diverting endovascular treatment that is very sensitive to small changes in pressure. This work presents the first step of our research, including the concept of the sensing system, a multi-striped piezoelectric PVDF pressure sensor design, its modeling, and preliminary simulation and experimental results. The results demonstrate the feasibility of the proposed sensing structure.

Mind-controlled micro-biomanipulation with position sensing feedback: System integration and validation

An integrated micro-biomanipulation system that can perform mind-controlled biomanipulation at micro scale is presented in the paper. The system incorporates a non-invasive electroencephalogram (EEG) device with a high-precision automated micromanipulator through high speed network. The human manipulation mind measured by the EEG can effectively drive the micromanipulator to perform the 2-D manipulation on bio-samples at micro scale. During the manipulation, the trace of human manipulation mind or movement signal is monitored by a custom-built high-precision position sensing detector (PSD) interface unit. In addition, topographical properties of all 14 EEG channels from the operator corresponding to 2-D mind movements are plotted and preliminarily analyzed. Experimental results validate the performance of the developed network-enabled and mind-controlled micro-biomanipulation system. Further work will focus on using the system to investigate neurobiofeedback mechanisms or manipulation behaviors of human brain during micro-biomanipulation and microassembly, so as to facilitate developing high-efficiency strategy of engineering approaches in micro/nano level.

Scissor mechanisms enabled compliant modular earthworm-like robot: Segmental muscle-mimetic design, prototyping and locomotion performance validation

Earthworms are the soft, tube-shaped, segmented worms who move with waves of muscular contractions. This paper presents our recently developed compliant modular earthworm-like robot with the novel segmental muscle-mimetic design unit that efficiently mimics earthworms segmental muscle contractions. The new class of segmental muscle-mimetic design unit relies on curvature of scissor mechanisms that can be extended and contracted smoothly through controlled servo motors. Connected numbers of the design units with the transmission mechanism, a multi-segment earthworm-like robot can be prototyped and it produces the peristaltic locomotion by controlling motors in each segment with different phase shift angles. In this paper, we detail the bioinspired concept and design of segmental muscle-mimetic unit, and demonstrate extensive simulation and experimental results on the design and the prototyped multi-segment robot. All results prove that both the design and the prototyped earthworm-like robot have excellent locomotion performance.

Study on construction of 3-loop expandable mechanism and simulation

To facilitate the application of foldable scissor-like element in engineering domain, this article focuses on the design of 3-loop expandable mechanism. The property of angulated element is revealed first to contribute to the modeling of theoretical model with 3-loop, and the concept of four expandable angulated elements sharing one square adaptor is then introduced to build the mechanical system. In order to verify the mechanical model, the kinetic simulation is conducted to make a comparison between theoretical and mechanical model. After validation, system identification method is used to obtain the transfer function of the expandable system based on the measured data. Finally, the primary experiment proves the feasibility of the expandable mechanism.

Enhancing measurement accuracy of position sensitive detector (PSD) systems using the Kalman filter and distortion rectifying

Factors affecting measurement accuracy of Position Sensitive Detector (PSD) systems consist of inaccuracies caused by interface circuits, system connection, outside environment change, and the semi-conductive properties of the sensor. The presence of these factors causes noises and distortions that are interpreted as a valid signal by the PSD system. As a result, these inaccuracies heavily degrade the PSD performance and hamper the measurement resolution and accuracy of the PSD system, which greatly limit its applications in micro/nano positioning systems. Our work is to (1) design a Kalman filter for the system that is used to recursively and optimally estimate the laser spot position value of the modeled second-order linear lateral effect PSD sensing system from a series of measurements mixed with these noises and (2) develop a distortion rectifying methodology to collect pincushion-type radial distortion associated with the lateral effect PSD systems, so as to enhance measurement accuracy in a larger active area of the PSD. After implementation, both the developed Kalman filter and distortion rectifying algorithm can greatly improve the measurement accuracy of the PSD systems. It will be very useful in a wide variety of applications that use a PSD embedded system.