Needle Aligned Ultrasound Image-Guided Access Through Dual-Segment Array.

Ultrasound (US) guided access for percutaneous nephrolithotomy (PCNL) is gaining popularity in the urology community as it reduces radiation risk. The most popular technique involves manual image-needle alignment. A misaligned needle however needs to be retracted and reinserted, resulting in a lengthened operation time and complications such as bleeding. These limitations can be mitigated through the co-registration between the US array and needle. The through-hole array concept provides the primary solution, including a hole at the center of the array. Because of the central opening, the image-needle alignment is achieved inherently. Previous literature has described applications that are limited to superficial and intravascular procedures, suggesting that developing a through-hole array for deeper target applications would be a new breakthrough. OBJECTIVE: Here, we present a dual-segment array with a central opening. As the prototype development, two segments of 32-element arrays are combined with an open space of 10 mm in length in between them. METHOD: We conducted phantom and ex-vivo studies considering the target depth of the 80-100 mm range. The image quality and needle visibility are evaluated by comparing the signal-to-noise ratio (SNR), full width at half maximum (FWHM), and contrast-to-noise ratio (CNR) results measured with a no-hole linear array under equivalent conditions. An ex-vivo study is performed using porcine kidneys with ceramic balls embedded to evaluate the needle access accuracy. RESULTS AND CONCLUSION: The mean needle access error of 20 trials is found to be 2.94 ±1.09 mm, suggesting its potential impact on realizing a simple and intuitive deep US image-guided access.

An mm-sized biomimetic directional microphone array for sound source localization in three dimensions.

Fly Ormia ochracea ears have been well-studied and mimicked to achieve subwavelength directional sensing, but their efficacy in sound source localization in three dimensions, utilizing sound from the X-, Y-, and Z-axes, has been less explored. This paper focuses on a mm-sized array of three Ormia ochracea ear-inspired piezoelectric MEMS directional microphones, where their in-plane directionality is considered a cue to demonstrate sound source localization in three dimensions. In the array, biomimetic MEMS directional microphones are positioned in a 120° angular rotation; as a result, six diaphragms out of three directional microphones keep a normal-axis relative to the sound source at six different angles in the azimuth plane starting from 0° to 360° in intervals of ±30°. In addition, the cosine-dependent horizontal component of the applied sound gives cues for Z-axis directional sensing. The whole array is first analytically simulated and then experimentally measured in an anechoic chamber. Both results are found to be compliant, and the angular resolution of sound source localization in three dimensions is found to be ±2° at the normal axis. The resolution at the azimuth plane is found to be ±1.28°, and the same array shows a ± 4.28° resolution when sound is varied from the elevation plane. Looking at the scope within this area combined with the presented results, this work provides a clear understanding of sound source localization in three dimensions.

Synergistic Effect of Reinforced Multiwalled Carbon Nanotubes and Boron Nitride Nanosheet-Based Hybrid Piezoelectric PLLA Scaffold for Efficient Bone Tissue Regeneration.

Electrospun poly(l-lactic acid) nanofibers (PLLANFs) have been receiving considerable attention in bone tissue engineering (BTE) due to their tunable biodegradability and remarkable in vitro and in vivo biocompatibility. However, deterioration in the mechanical strength of PLLANFs during the regeneration process leads to low osteoinductive performances. Additionally, their high hydrophobicity and limited piezoelectric properties have to be addressed concerning BTE. Herein, we report an efficient approach for fabricating high-performance PLLANF hybrid scaffolds for BTE by reinforcing amphiphilic triblock copolymer pluronic F-127 (PL)-functionalized nanofillers (PL-functionalized carboxylated multiwalled carbon nanotubes (PL-cMWCNTs) and PL-functionalized exfoliated boron nitride nanosheets (PL-EBN)). The synergistic reinforcement effect from one-dimensional (1D) electrically conducting PL-cMWCNTs and two-dimensional (2D) piezoelectric PL-EBN was remarkable in PLLANFs, and the obtained PL-Hybrid (PL-cMWCNTs + PL-EBN) reinforced scaffolds have outperformed the mechanical strength, wettability, and piezoelectric performances of pristine PLLANFs. Consequently, in vitro biocompatibility results reveal the enhanced proliferation of MC3T3-E1 cells on PL-Hybrid nanofiber scaffolds. Furthermore, the ALP activity, ARS staining, and comparable osteogenic gene expression results demonstrated significant osteogenic differentiation of MC3T3-E1 cells on PL-Hybrid nanofiber scaffolds than on the pristine PLLANF scaffold. Thus, the reported approach for constructing high-performance piezoelectric biodegradable scaffolds for BTE by the synergistic effect of PL-cMWCNTs and PL-EBN holds great promise in tissue engineering applications.

A-SEE: Active-Sensing End-effector Enabled Probe Self-Normal-Positioning for Robotic Ultrasound Imaging Applications.

Conventional manual ultrasound (US) imaging is a physically demanding procedure for sonographers. A robotic US system (RUSS) has the potential to overcome this limitation by automating and standardizing the imaging procedure. It also extends ultrasound accessibility in resource-limited environments with the shortage of human operators by enabling remote diagnosis. During imaging, keeping the US probe normal to the skin surface largely benefits the US image quality. However, an autonomous, real-time, low-cost method to align the probe towards the direction orthogonal to the skin surface without pre-operative information is absent in RUSS. We propose a novel end-effector design to achieve self-normal-positioning of the US probe. The end-effector embeds four laser distance sensors to estimate the desired rotation towards the normal direction. We then integrate the proposed end-effector with a RUSS system which allows the probe to be automatically and dynamically kept to normal direction during US imaging. We evaluated the normal positioning accuracy and the US image quality using a flat surface phantom, an upper torso mannequin, and a lung ultrasound phantom. Results show that the normal positioning accuracy is 4.17 ± 2.24 degrees on the flat surface and 14.67 ± 8.46 degrees on the mannequin. The quality of the RUSS collected US images from the lung ultrasound phantom was equivalent to that of the manually collected ones.

Sound source localization by Ormia ochracea inspired low-noise piezoelectric MEMS directional microphone.

The single-tone sound source localization (SSL) by majority of fly Ormia ochracea's ears-inspired directional microphones leaves a limited choice when an application like hearing aid (HA) demands broadband SSL. Here, a piezoelectric MEMS directional microphone using a modified mechanical model of fly's ear has been presented with primary focus to achieve SSL in most sensitive audio bands to mitigate the constraints of traditional SSL works. In the modified model, two optimized rectangular diaphragms have been pivoted by four optimized torsional beams; while the backside of the whole structure has been etched. As a result, the SSL relative to angular rotation of the incoming sound depicts the cosine dependency as an ideal pressure-gradient sensor. At the same time, the mechanical coupling leads the magnitude difference between two diaphragms which has been accounted as SSL in frequency domain. The idea behind this work has been analytical simulated first, and with the convincing mechanical results, the designed bio-inspired directional microphone (BDM) has been fabricated using commercially available MEMSCAP based on PiezoMUMPS processes. In an anechoic chamber, the fabricated device has been excited in free-field sound, and the SSL at 1 kHz frequency, rocking frequency, bending frequency, and in-between rocking and bending frequencies has been found in full compliance with the given angle of incidence of sound. With the measured inter-aural sensitivity difference (mISD) and directionality, the developed BDM has been demonstrated as a practical SSL device, and the results have been found in a perfect match with the given angle of incidence of sound. Furthermore, to facilitate the SSL in noisy environment, the noise has been optimized in all scopes, like the geometry of the diaphragm, supportive torsional beam, and sensing. As a result, the A-weighted noise of this work has been found less than 23 dBA across the audio bands, and the equivalent-input noise (EIN) has been found to be 25.52 dB SPL at 1 kHz frequency which are the lowest ever reported by a similar device. With the developed SSL in broadband-in addition to the lowest noise-the developed device can be extended in some audio applications like an HA device.