Artificial skin with sense of touch for robotic hand

This Master of Science thesis proposes a method to fabricate a soft robotic hand (SRH) with a sense of touch. Electronic skin (e-skin) – flexible and/or stretchable electronics that mimic the functions of human skin – is actively researched and developed for robotic applications (especially humanoid robots), owing to the high demand of robots that can safely interact with humans in the different industrial sectors. E-skin is also in demand for high-quality prosthetics that leverage the advances in brain-machine interfaces. The emphasis in this thesis is on the fabrication and characterization of an e-skin. The objective of this skin is to give an estimation of the amount of force exerted on it, which is beneficial for the SRH to feedback information about the manipulated object. We are aiming in this thesis to use fabrication approach of rapid prototyping to fulfill the following characteristics in SRH: actuation, soft touch, and sensation capabilities. Accordingly, we propose using 3D printing to fabricate both hand skeleton and molds to be used for artificial skin casting. Fingers are actuated by driving cables which are extended through inner channels embedded inside the hand skeleton. The specific goal of this thesis is to compare two different types of touch sensors for e-skin, one piezoresistive and one capacitive. The selected technologies are discussed in detail, and sensors based on these technologies are fabricated, characterized and analyzed comparatively. The results showed the potential of disclosing tactile information by implanting sensors in SRH. With comparing the piezoresistive sensor to the capacitive sensor, the latter exhibited a simpler approach for integration with the artificial skin to develop e-skin because it was feasible to fabricate the e-skin in one step instead of fabricating the artificial skin and the sensor separately. From the perspective of performance, capacitive sensor demonstrated higher efficiency in general compared to the piezoresistive sensor. As an example, the response in the piezore-sistive and capacitive sensor, showed linearity of 5.3% (on a logarithmic scale) 1.8% for both sensors, respectively. Moreover, the signal hysteresis in the capacitive sensor was better with a deviation of 2.7%, compared to 18.2% for the piezoresistive sensor. Finally, a SRH with integrated touch sensors is demonstrated. This paves the way for further research on utilizing the developed e-skin for objects recognition during hand gripping or designing a closed control loop system for dexterous control over the force of gripping. Moreover, an efficient artificial limb with sensation capabilities can be developed to feedback sensory information to the brain of the patient after being processed by a brain-machine interface

Hybrid active damping of LCL-filtered grid connected converter

A method for hybrid active damping in power converters connected to a weak grid using an LCL filter is proposed. It uses feedback of the grid current and capacitor voltage and is derived as an equivalent to the capacitor current feedback active damping method. A co-design procedure for the grid current controller with the proposed hybrid active damping method is presented. The robustness, system bandwidth and harmonic rejection are studied. The proposed method is applied to a single grid connected converter with variable grid inductance to investigate its ability to damp different system resonance frequencies and its effectiveness is verified via frequency domain analysis and time domain simulation

Imaging features of rare mesenychmal liver tumours: beyond haemangiomas.

Tumours arising from mesenchymal tissue components such as vascular, fibrous and adipose tissue can manifest in the liver. Although histopathology is often necessary for definitive diagnosis, many of these lesions exhibit characteristic imaging features. The radiologist plays an important role in suggesting the diagnosis, which can direct appropriate immunohistochemical staining at histology. The aim of this review is to present clinical and imaging findings of a spectrum of mesenchymal liver tumours such as haemangioma, epithelioid haemangioendothelioma, lipoma, PEComa, angiosarcoma, inflammatory myofibroblastic tumour, solitary fibrous tumour, leiomyoma, leiomyosarcoma, Kaposi sarcoma, mesenchymal hamartoma, undifferentiated embryonal sarcoma, rhabdomyosarcoma and hepatic metastases. Knowledge of the characteristic features of these tumours will aid in guiding the radiologic diagnosis and appropriate patient management

Diagnostic yield of percutaneous image‐guided tissue biopsy of focal hepatic lesions in cancer patients

BACKGROUND: The diagnostic yield was evaluated of percutaneous image‐guided tissue biopsy of hepatic lesions identified on computed tomography performed for staging of a primary malignancy, and it was determined how often the biopsy result was unexpectedly negative, benign, or secondary to a second unknown malignancy. METHODS: In a retrospective investigation from 1998 through 2008, 580 patients with primary malignancies had indeterminate focal hepatic lesions and underwent percutaneous image‐guided biopsy; 369 patients had lesions in their liver at first cross‐sectional imaging, performed for staging; 211 patients had a negative liver imaging study, followed by the subsequent appearance of at least 1 indeterminate suspicious lesion. The results of percutaneous image‐guided tissue biopsies were compared with the histology of the primary malignancy. RESULTS: Liver biopsies were performed in 580 patients (288 men and 292 women; age, 25‐92 years; mean age, 61 years). The most common primary malignancies were pancreatic (n = 96), breast (n = 85), melanoma (n = 57), esophageal (n = 51), lung (n = 47), colorectal (n = 37), and urothelial tumors (n = 26). Biopsy results were positive for malignancy in 528 (91%) cases. Among the positive biopsies, 29 (5%) cases had pathology results different from the primary tumor. Of the 52 biopsies negative for malignancy, 20 yielded a specific benign diagnosis, and 32 were nondiagnostic. CONCLUSIONS: If all liver lesions had been assumed to be metastases, as expected secondary to the known primary tumor, then the true or presumed alternate diagnosis would have been missed in 60 (10.3%) of the 580 cases. The authors did not attempt to determine whether actual clinical management changed based on these 60 liver biopsy results, so this number is an upper bound on management change. On the basis of these results, and given the minimal complication rate of liver biopsy, the authors suggest that liver biopsy should still be performed in the types of cases studied here, despite the finding that the vast majority of biopsies produced the expected result and presumably did not change patient management. Cancer 2011;. © 2011 American Cancer Society. The diagnostic yield was evaluated of percutaneous image‐guided tissue biopsy of hepatic lesions identified on computed tomography performed for staging of a primary malignancy. The authors suggest that liver biopsy should still be performed in the types of cases studied, although the vast majority of biopsies produced the expected result and presumably did not change patient management.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86797/1/25980_ftp.pd

CT and MRI Findings of Sclerosing Angiomatoid Nodular Transformation of the Spleen: Spoke Wheel Pattern

Sclerosing angiomatoid nodular transformation of the spleen is a recently described benign pathologic entity that is characterized by round shaped vascular spaces that are lined by endothelial cells, and the spaces are circumscribed by granulomatoid structures. Microscopically, all the reported cases had multiple angiomatoid nodules in a fibrosclerotic stroma. Each angiomatoid nodule was made up of slit-like, round or irregular shaped vascular spaces that were lined by endothelial cells and interspersed ovoid cells. We present here the CT and dynamic gadolinium-enhanced MR findings of a patient with sclerosing angiomatoid nodular transformation. The spoke-wheel pattern that was observed on MRI in this case may be an important imaging clue for making the correct diagnosis of this benign lesion

Liver imaging reporting and data system: An expert consensus statement

The increasing incidence and high morbidity and mortality of hepatocellular carcinoma (HCC) have inspired the creation of the Liver Imaging Reporting and Data System (LI-RADS). LI-RADS aims to reduce variability in exam interpretation, improve communication, facilitate clinical therapeutic decisions, reduce omission of pertinent information, and facilitate the monitoring of outcomes. LI-RADS is a dynamic process, which is updated frequently. In this article, we describe the LI-RADS 2014 version (v2014), which marks the second update since the initial version in 2011

Primary hepatic lymphoma: Imaging findings

Primary hepatic lymphoma (PHL) is rare, accounting for less than 1% of all extranodal lymphomas. In this article, we retrospectively reviewed the imaging features of 12 pathologically proven cases of primary hepatic lymphoma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71586/1/j.1754-9485.2009.02081.x.pd

Knowing the ABCs: Teaching the principles of radiology to medical students in Turkey

Background: Radiology education in Turkey is mainly taught during clinical years of medical school and often lacks main principles. Exposure to the fundamentals of radiology at an early stage of medical education may drastically help students generate a better understanding of radiology and expand their interest in the specialty. With the Principles of Radiology Course that we provided, pre- and post-session tests, and assessment survey at the end of the course, we aimed to evaluate the effectiveness of such an online course among Turkish medical students. Methods: A total of nine online sessions on imaging modalities principles was developed by radiology professors. Each session was given through Zoom by radiologists from different U.S.-institutions to Turkish medical students from state (n = 33) and private (n = 8) universities. Pretests and post-tests were given to participants via Qualtrics before and after each session, respectively. Paired two-sample t-tests were conducted to detect the variance and p=-.05 was used as the significance level. An evaluation survey was distributed at the end of the course to collect their feedback through SurveyMonkey. Results: A total of 1,438 predominantly Turkish (99.32%) medical students engaged with this course. An average of 506 students completed both pre-test and post-test. There was a statistically significant (p <.001) increase in the scores in post-test (mean[range]:7.58[5.21–8.53]) relative to pre-test (mean[range]:5.10[3.52–8.53]). Four hundred and thirty-nine participants (F/M:63.33%/35.54%) completed the end-of-course survey. A total of 71% and 69.70% of the participants strongly agreed that the course would be useful in their clinical practice and had increased their understanding of radiology. They also reported that their level of confidence in the subjects had increased 68% and reached a weighted average of 3.09/4. The survey revealed that 396 (90.21%) of the participants strongly or somewhat agree that introductory principles and concepts should be presented in earlier years of medical education. Compared to in-person education, 358 (81.55%) found the course extremely or very convenient. Conclusion: Online lecture series consisting of the principles of the radiological imaging modalities can be offered to Turkish medical students to enhance their grasp of the various imaging modalities and their correct clinical application

MR imaging features of benign retroperitoneal extra-adrenal paragangliomas

The goal of this study was to retrospectively review the magnetic resonance imaging (MRI) features of retroperitoneal extra-adrenal paragangliomas and to evaluate the diagnostic capabilities of MRI. Twenty-four patients with confirmed benign retroperitoneal extra-adrenal paragangliomas who underwent preoperative MRI and surgical resection were enrolled. The patients’ clinical characteristics and MRI features were reviewed by two radiologists. There were no significant differences in the qualitative and quantitative MRI features were determined by the reviewers. High signal intensity in T2- weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was observed in all tumors. In contrast T1-weighted imaging (T1WI) in the arterial phase, 83.33% of the tumors were clearly enhanced. In 87.5% of cases, a persistent enhancement pattern was observed in the venous and delayed phases, and 12.5% of tumors showed a “washout” pattern. The tumor capsule, intratumoral septum and degenerations were visualized in the tumors and may be helpful in the qualitative diagnosis of extraadrenal paragangliomas in MRI. MRI was useful in locating the position, determining the tumor ranges and visualizing the relationship between the tumors and adjacent structures. The presence of typical clinical symptoms and positivity of biochemical tests are also important factors in making an accurate preoperative diagnosis

Perforated Meckel diverticulum

Perforation of a Meckel diverticulum (MD) is a rare complication that can often mimic appendicitis. This case report identifies a child who presented to our Emergency Department (ED) with right lower quadrant abdominal pain, free fluid and air in the abdomen and pelvis, and inflammatory changes visualized on Ultrasonography (US) and computer tomography (CT) scan. In our patient, ruptured appendicitis was suspected, and the diagnosis of ruptured MD was ultimately made by laparoscopy. This case demonstrates that a healthy degree of suspicion for complicated MD should be present when dealing with a questionable diagnosis of appendicitis, particularly in the pediatric population