Development of multi-angle fiber array for accurate measurement of flexion and rotation in human joints

Herein, we have proposed a method that uses a highly stretchable and conductive fiber-based multi-angle fiber array, which precisely measures human joint motion in various degrees of freedom (flexion and rotation) at the shoulders, knees, and wrists in real time. By embedding conductive carbon nanotubes (CNTs) within spandex fibers of high elasticity and shape recovery ratio, we monitored joint motion stably without degrading the fiber’s conductivity even during repeated stretching and contraction of different lengths. The strain occurring in a specific direction was monitored using mapping images generated due to the change in resistance that occurred when 12 CNT-embedded spandex fibers arranged in radial lines at intervals of 15° were stretched or contracted by an external force. The proposed high-precision joint-monitoring technology measures human motion accurately and is applicable for use in wearable healthcare devices that require precise measurements.

Measurement Capability of Laser Ultrasonic Inspection System for Evaluation of Ball-Grid Array Package Solder Balls

Laser ultrasonic inspection is a novel, noncontact, and nondestructive technique to evaluate the quality of solder interconnections in microelectronic packages. In this technique, identification of defects or failures in solder interconnections is performed by comparing the out-of-plane displacement signals, which are produced from the propagation of ultrasonic waves, from a known good reference sample and sample under test. The laboratory-scale dual-fiber array laser ultrasonic inspection system has successfully demonstrated identifying the defects and failures in the solder interconnections in advanced microelectronic packages such as chip-scale packages, plastic ball grid array packages, and flip-chip ball grid array packages. However, the success of any metrology system depends upon precise and accurate data to be useful in the microelectronic industry. This paper has demonstrated the measurement capability of the dual-fiber array laser ultrasonic inspection system using gage repeatability and reproducibility analysis. Industrial flip-chip ball grid array packages have been used for conducting experiments using the laser ultrasonic inspection system and the inspection data are used to perform repeatability and reproducibility analysis. Gage repeatability and reproducibility studies have also been used to choose a known good reference sample for comparing the samples under test.

Optical Fiber Array Sensor for Force Estimation and Localization in TAVI Procedure: Design, Modeling, Analysis and Validation

Transcatheter aortic valve implantation has shown superior clinical outcomes compared to open aortic valve replacement surgery. The loss of the natural sense of touch, inherited from its minimally invasive nature, could lead to misplacement of the valve in the aortic annulus. In this study, a cylindrical optical fiber sensor is proposed to be integrated with valve delivery catheters. The proposed sensor works based on intensity modulation principle and is capable of measuring and localizing lateral force. The proposed sensor was constituted of an array of optical fibers embedded on a rigid substrate and covered by a flexible shell. The optical fibers were modeled as Euler–Bernoulli beams with both-end fixed boundary conditions. To study the sensing principle, a parametric finite element model of the sensor with lateral point loads was developed and the deflection of the optical fibers, as the determinant of light intensity modulation was analyzed. Moreover, the sensor was fabricated, and a set of experiments were performed to study the performance of the sensor in lateral force measurement and localization. The results showed that the transmitted light intensity decreased up to 24% for an external force of 1 N. Additionally, the results showed the same trend between the simulation predictions and experimental results. The proposed sensor was sensitive to the magnitude and position of the external force which shows its capability for lateral force measurement and localization.