Toward Development of Novel Remote Ultrasound Robotic System Using Soft Robotics Technology

This paper reports on the development of a novel soft robotic system for remote ultrasound applications. Direct contact of the ultrasound probe with the patient's body represents a safety risk and therefore control of the probe's positioning and applied force is a crucial task. The proposed robot uses a passive control system that provides safe interaction between the robot and the patient by leveraging soft robotics technology. The soft robot's structure can be considered as a nonlinear spring which can be designed to exert a safe force within the robot's workspace to guarantee the safety of human-robot interaction. The literature suggests that effective ultrasound imaging of both the heart and abdomen requires six degrees-of-freedom. These degrees-of-freedom consist of three translational motions, which are achieved using a novel hybrid soft cable-driven parallel robot, and three wrist motions, which is based on a universal joint design. The experimental results show that the robot can achieve all these six degrees-of-freedom, and its blocking force can be engineered to generate a uniform force within the workspace.

Differential sensitivities to blood pressure variations in internal carotid and intracranial arteries: a numerical approach to stroke prediction

Stroke remains a global health concern, necessitating early prediction for effective management. Atherosclerosis-induced internal carotid and intra cranial stenosis contributes significantly to stroke risk. This study explores the relationship between blood pressure and stroke prediction, focusing on internal carotid artery (ICA) branches: middle cerebral artery (MCA), anterior cerebral artery (ACA), and their role in hemodynamics. Computational fluid dynamics (CFD) informed by the Windkessel model were employed to simulate patient-specific ICA models with introduced stenosis. Central to our investigation is the impact of stenosis on blood pressure, flow velocity, and flow rate across these branches, incorporating Fractional Flow Reserve (FFR) analysis. Results highlight differential sensitivities to blood pressure variations, with M1 branch showing high sensitivity, ACA moderate, and M2 minimal. Comparing blood pressure fluctuations between ICA and MCA revealed heightened sensitivity to potential reverse flow compared to ICA and ACA comparisons, emphasizing MCA's role. Blood flow adjustments due to stenosis demonstrated intricate compensatory mechanisms. FFR emerged as a robust predictor of stenosis severity, particularly in the M2 branch. In conclusion, this study provides comprehensive insights into hemodynamic complexities within major intracranial arteries, elucidating the significance of blood pressure variations, flow attributes, and FFR in stenosis contexts. Subject-specific data integration enhances model reliability, aiding stroke risk assessment and advancing cerebrovascular disease understanding.

An analytical method informed by clinical imaging data for estimating outlet boundary conditions in computational fluid dynamics analysis of carotid artery blood flow

Stroke occur mainly due to arterial thrombosis and rupture of cerebral blood vessels. Previous studies showed that blood flow-induced wall shear stress is an essential bio marker for estimating atherogenesis. It is a common practice to use computational fluid dynamics (CFD) simulations to calculate wall shear stress and to quantify blood flow. Reliability of predicted CFD results greatly depends on the accuracy of applied boundary conditions. Previously, the boundary conditions were estimated by varying values so that they matched the clinical data. It is applicable upon the availability of clinical data. Meanwhile, in most cases all that can be accessed are arterial geometry and inflow rate. Consequently, there is a need to devise a tool to estimate boundary values such as resistance and compliance of arteries. This study proposes an analytical framework to estimate the boundary conditions for a carotid artery based on the geometries of the downstream arteries available from clinical images.

A Bioinspired Compliant 3D-Printed Soft Gripper

A compliant three-dimensional (3D)-printed soft gripper is designed based on the bioinspired spiral spring in this study. The soft gripper is then 3D-printed using a suitable thermoplastic filament material to deliver the desired performance. The sensorless mechanism introduced in this study provides adequate compliance with a single linear actuator for interacting with delicate objects, such as manipulation of human biological materials and fruit picking. The kinematic and dynamic models of the monolithic gripper are derived analytically as well as by means of finite element analysis to synthesize its functionality. The fabricated gripper module is installed on a robot arm to demonstrate the efficacy of design for picking and placing fruits without damaging them. The presented mechanism could be customized and used in the medical and agricultural sectors with diverse geometry objects.

Blood Pressure Sensors: Materials, Fabrication Methods, Performance Evaluations and Future Perspectives

Advancements in materials science and fabrication techniques have contributed to the significant growing attention to a wide variety of sensors for digital healthcare. While the progress in this area is tremendously impressive, few wearable sensors with the capability of real-time blood pressure monitoring are approved for clinical use. One of the key obstacles in the further development of wearable sensors for medical applications is the lack of comprehensive technical evaluation of sensor materials against the expected clinical performance. Here, we present an extensive review and critical analysis of various materials applied in the design and fabrication of wearable sensors. In our unique transdisciplinary approach, we studied the fundamentals of blood pressure and examined its measuring modalities while focusing on their clinical use and sensing principles to identify material functionalities. Then, we carefully reviewed various categories of functional materials utilized in sensor building blocks allowing for comparative analysis of the performance of a wide range of materials throughout the sensor operational-life cycle. Not only this provides essential data to enhance the materials' properties and optimize their performance, but also, it highlights new perspectives and provides suggestions to develop the next generation pressure sensors for clinical use.

Patient-specific 3D-printed Splint for Mallet Finger Injury

Despite the frequency of mallet finger injuries, treatment options can often be costly, time-consuming, and ill-fitted. Three-dimensional (3D) printing allows for the production of highly customized and inexpensive splints, which suggests potential efficacy in the prescription of casts for musculoskeletal injuries. This study explores how the use of engineering concepts such as 3D printing and topology optimization (TO) can improve outcomes for patients. 3D printing enables the direct fabrication of the patient-specific complex shapes while utilizing finite element analysis and TO in the design of the splint allowed for the most efficient distribution of material to achieve mechanical requirements while reducing the amount of material used. The reduction in used material leads to significant improvements in weight reduction and heat dissipation, which would improve breathability and less sweating for the patient, greatly increasing comfort for the duration of their recovery.

Stereolithography for Personalized Left Atrial Appendage Occluders

Advancements in 3D additive manufacturing have spurred the development of effective patient-specific medical devices. Prior applications are limited to hard materials, however, with few implementations of soft devices that better match the properties of natural tissue. This paper introduces a rapid, low cost, and scalable process for fabricating soft, personalized medical implants via stereolithography of elastomeric polyurethane resin. The effectiveness of this approach is demonstrated by designing and manufacturing patient-specific endocardial implants. These devices occlude the left atrial appendage, a complex structure within the heart prone to blood clot formation in patients with atrial fibrillation. Existing occluders permit residual blood flow and can damage neighboring tissues. Here, the robust mechanical properties of the hollow, printed geometries are characterized and stable device anchoring through in vitro benchtop testing is confirmed. The soft, patient-specific devices outperform non-patient-specific devices in embolism and occlusion experiments, as well as in computational fluid dynamics simulations.

Treatment with carbon dioxide laser of painful skin metastases from a laryngeal neuroendocrine carcinoma

An 82-year-old man presented with multiple, exquisitely painful skin metastases from an atypical carcinoid tumour of the larynx. These were treated successfully with carbon dioxide laser. To our knowledge, this is the first reported case of laser treatment used in the management of neuroendocrine skin metastases.

Regional and transmural density of interstitial cells of Cajal in human colon and rectum

The interstitial cells of Cajal (ICC) are thought to play an important role in the control of gut motility. The regional and transmural pattern of distribution of ICC in the normal human colon and rectum was evaluated with immunohistochemistry using an anti-c-kit antibody. The transmural distribution of ICC was constant throughout the whole colon, the density of ICC was significantly greater at the myenteric plexus than at either the longitudinal or circular muscle layers, and in the rectum the transmural distribution was more even. Regionally, at the myenteric plexus, the transverse colon had a significantly greater density of ICC compared with the right colon (P = 0.038), left colon (P = 0.006), and rectum (P = 0.008). The pattern of distribution of ICC identified in this study is consistent with the proposed roles of ICC as colorectal pacemakers, intermediaries of the neural control of muscle activity, and coordinators of colorectal muscle activity. The highest density of ICC was at the myenteric plexus of the transverse colon, which is the proposed region of pacemaking activity.

Distribution of the interstitial cells of Cajal in the human anorectum

The interstitial cells of Cajal are proposed to have a role in the control of gut motility. The aim of this study was to establish the distribution of interstitial cells of Cajal in the wall of the normal human anorectum. Interstitial cells of Cajal express the proto-oncogene c-kit. Interstitial cells of Cajal were identified in the colon by immunohistochemical staining, using a rabbit polyclonal anti-c-kit antibody. Anorectal tissue was obtained at surgical resection for carcinoma of the colorectum. Density of interstitial cells of Cajal was graded. Statistical analysis was performed using chi2 tests. In the longitudinal and circular muscle layers of the rectum interstitial cells of Cajal were seen in the bulk of the muscle layer. In the intermuscular plane interstitial cells of Cajal encased the myenteric plexus. Interstitial cells of Cajal were found at the inner margin of the circular muscle and in association with neural elements of the submuscular plexus. Within the internal anal sphincter interstitial cells of Cajal were infrequently scattered among the muscle fibres. The density of interstitial cells of Cajal in the internal anal sphincter was significantly lower than that observed in the circular muscle layer of the rectum (P = 0.014). In conclusion, interstitial cells of Cajal are evenly distributed in the layers of the muscularis propria of the rectum, but have a lower density in the internal anal sphincter.