액정폴리머를 기반의 소형, 안구밀착형, 장기안정적인 인공망막장치

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 김성준.A novel retinal prosthetic device was developed using liquid crystal polymer (LCP) to address the problems associated with conventional metal- and polymer-based devices: the hermetic metal package is bulky, heavy and labor-intensive, whereas a thin, flexible and MEMS-compatible polymer-based system is not durable enough for chronic implantation. Exploiting the advantageous properties of LCP such as a low moisture absorption rate, thermo-bonding and thermo-forming, a small, light-weight, long-term reliable retinal prosthesis was fabricated that can be conformally attached on the eye-surface. A LCP fabrication process using monolithic integration and conformal deformation was established enabling miniaturization and a batch manufacturing process as well as eliminating the need for feed-through technology. The fabricated 16-channels LCP-based retinal implant had 14 mm-diameter with the maximum thickness of 1.4 mm and weight of 0.4 g and could be operated wirelessly up to 16 mm of distance in the air. The long-term reliability of the all-LCP retinal device was evaluated in vitro as well as in vivo. Because an all-polymer implant introduces intrinsic gas permeation for which the traditional helium leak test for metallic packages was not designed to quantify, a new set of reliability tests were designed and carried out specifically for all-polymer implants. Moisture ingress through various pathways were classified into polymer surface, polymer-polymer and polymer-metal adhesions each of which were quantitatively investigated by analytic calculation, in vitro aging test of electrode part and package part, respectively. The functionality and long-term implantation stability of the device was verified through in vivo animal experiments by measuring the cortical potential and monitoring implanted dummy devices for more than a year, respectively. Samples of the LCP electrodes array failed after 114 days in 87°C salin as a result of water penetration through the LCP-metal interface. An eye-confirmable LCP package survived more than 35 days in an accelerated condition at 87°C. The in vivo results confirmed that no adverse effects around the retina were observed after implantation of the device for more than a year.ABSTRACT i Contents iv List of Figures xi List of Tables xxi Chapter 1 : Introduction 1 1.1. Neuroprosthetic devices 1 1.2. Retinal prosthesis 2 1.2.1. Concept 2 1.2.2. Three approaches 3 1.2.3. Camera vs. Photodiode 4 1.3. Conventional devices 5 1.4. Liquid Crystal Polymer (LCP) 7 1.4.1. Low moisture absorption and permeability 9 1.4.2. Thermoplastic property 9 1.4.3. Compatibility with MEMS technologies 10 1.4.4. RF characteristics 10 1.5. LCP-based retinal prosthesis 11 1.6. Long-term reliability 12 1.7. Dissertation outline 14 Chapter 2: Methods 16 2.1. System Overview 16 2.2. Microfabrication on LCP 18 2.2.1. Limitations of the previous microfabrication technique on LCP 19 2.2.2. Improved LCP-based microfabrication 22 2.2.2.1. Electroplated micro-patterning 23 2.2.2.2. Laser-thinning for higher flexibility 24 2.2.2.3. Laser-ablation for site opening 25 2.3. All-LCP Monolithic Fabrication 26 2.3.1. Multilayered integration 29 2.3.1.1. Electrical components 29 2.3.1.2. Thermal lamination 32 2.3.1.3. Layer configuration 34 2.3.2. Thermal deformation 35 2.3.2.1. Deformation process 35 2.3.2.2. Wavy lines for stretchability 36 2.3.2.3. Electrical properties of the deformed coil 40 2.3.3. Circuit Assembly 40 2.3.3.1. Stimulation ASIC 40 2.3.3.2. Surrounding circuitries 41 2.3.4. Packaging 43 2.3.5. Laser Machining 44 2.4. Device characterization 44 2.4.1. Transmitter Circuit and Wireless Operation 45 2.4.1.1. Transmitter circuit 45 2.4.1.2. Transmitter coil 46 2.4.1.3. Wireless operation test 46 2.4.2. Electrochemical measurements 48 2.5. Long-term reliability tests in vitro 49 2.5.1. Failure mechanisms of an all-LCP device 49 2.5.2. Analytic calculation 51 2.5.3. Long-term reliability tests in accelerated environment 55 2.5.3.1. Long-term reliability of electrode array 55 2.5.3.2. Long-term reliability of package 57 2.5.3.3. Long-term reliability of complete device 58 2.5.4. Long-term electrochemical stability 59 2.6. Acute and Chronic Evaluation in vivo 60 2.6.1. Surgical implantation 60 2.6.2. Acute functionality test 62 2.6.3. Long-term implantation stability 63 Chapter 3: Results 64 3.1. Microfabrication on LCP 64 3.1.1. Electroplated micro-patterning 64 3.1.2. Laser-ablation for site opening 67 3.1.3. Laser-thinning for higher flexibility 69 3.2. All-LCP Monolithic fabrication 71 3.2.1. Multilayered integration 71 3.2.2. Thermal deformation 73 3.2.2.1. Deformation results 73 3.2.2.2. Wavy lines for stretchability 74 3.2.2.3. Effect on the electrical properties 74 3.2.3. Circuit assembly 76 3.2.4. Packaging 77 3.2.5. Laser machining 79 3.3. Device Characterization 80 3.3.1. General specifications 81 3.3.2. Transmitter circuit and coil 83 3.3.3. Wireless operation 83 3.3.4. Electrochemical measurements 84 3.4. Long-term reliability tests in vitro 86 3.4.1. Analytic calculation 87 3.4.2. Long-term reliability tests in accelerated condition 90 3.4.2.1. Long-term reliability of electrode arrays 90 3.4.2.2. Long-term reliability of package 92 3.4.2.3. Long-term reliability of complete device 93 3.4.3. Long-term Electrochemical stability 93 3.5. Acute and chronic evaluation in vivo 95 3.5.1. Surgical implantation 95 3.5.2. Acute functionality test 96 3.5.3. Long-term implantation stability 97 Chapter 4: Discussion 100 4.1. Comparison with conventional devices 100 4.2. Potential applications 102 4.3. Opportunities for further improvements 102 4.4. Long-term reliability 104 Chapter 5: Conclusion 108 Reference 110 국문초록 118 감사의 글 121Docto

후복막 접근법을 통한 복강경 부신절제술의 초기 경험

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Coexistence of chronic lymphocytic thyroiditis with papillary thyroid carcinoma: clinical manifestation and prognostic outcome

The study aimed to identify the clinical characteristics of coexisting chronic lymphocytic thyroiditis (CLT) in papillary thyroid carcinoma (PTC) and to evaluate the influence on prognosis. A total of 1,357 patients who underwent thyroid surgery for PTC were included. The clinicopathological characteristics were identified. Patients who underwent total thyroidectomy (n = 597) were studied to evaluate the influence of coexistent CLT on prognosis. Among the total 1,357 patients, 359 (26.5%) had coexistent CLT. In the CLT group, the prevalence of females was higher than in the control group without CLT (P < 0.001). Mean tumor size and mean age in the patients with CLT were smaller than without CLT (P = 0.040, P = 0.047, respectively). Extrathyroidal extension in the patients with CLT was significantly lower than without CLT (P = 0.016). Among the subset of 597 patients, disease-free survival rate in the patients with CLT was significantly higher than without CLT (P = 0.042). However, the multivariate analysis did not reveal a negative association between CLT coexistence and recurrence. Patients with CLT display a greater female preponderance, smaller size, younger and lower extrathyroidal extension. CLT is not a significant independent negative predictive factor for recurrence, although presence of CLT indicates a reduced risk of recurrence.ope

신경 보완 장치를 위한 다층 평면형 코일 개발

학위논문 (석사)-- 서울대학교 대학원 : 전기. 컴퓨터공학부, 2011.2. 김성준.Maste

Initial Experience With Robotic Gasless Transaxillary Thyroidectomy for the Management of Graves Disease: Comparison of Conventional Open Versus Robotic Thyroidectomy

PURPOSE: The aim of this study was to report on our initial experiences with robotic gasless transaxillary thyroidectomy for the management of Graves disease (GD). METHODS: Among 257 patients with benign thyroid diseases who underwent thyroidectomy, 16 patients who underwent thyroidectomy for GD were analyzed from January 2009 to December 2010. These patients included 7 individuals who underwent robotic gasless transaxillary thyroidectomy (robot group; RG) and 9 who underwent conventional open thyroidectomy (open group; OG). Regardless of the type of surgery, all patients underwent subtotal thyroidectomy. The clinical characteristics and surgical outcomes of the 2 groups were compared. RESULTS: Patients in the RG were significantly younger at the time of surgery compared with those in the OG (P=0.028). The mean operative time was 171.29±18.88 minutes for the RG and 89.44±7.08 minutes for the OG (P=0.001). The mean weight of the resected glands was 77.43±12.29 g for the RG and 85.56±20.37 g for the OG (P=0.896). The RG had a significantly shorter mean hospitalization period of 3.0±0 days compared with 3.78±0.22 days of the OG. The mean number of times analgesics were used for pain control were 2.43±0.29 for the RG and 4.0±0.52 for the OG (P=0.039). No cases in the RG were converted to open thyroidectomy. During a mean follow-up period of 14.43±1.49 months for the RG, no patients continued antithyroid drugs or developed recurrent GD. CONCLUSIONS: Robotic gasless transaxillary thyroidectomy is a technically feasible and safe procedure for the patients with GD that results in a scarless outcome on the neck. This procedure can be a promising alternative for endoscopic or conventional open thyroidectomy for the management of GD.ope

Robot-assisted Posterior Retroperitoneoscopic Adrenalectomy Using Single-port Access: Technical Feasibility and Preliminary Results

BACKGROUND: Posterior retroperitoneoscopic adrenalectomy (PRA) has several benefits compared with transperitoneal adrenalectomy in that it is safe and has a short learning curve. In addition, it provides direct short access to the target organ, prevents irritation to the intraperitoneal space, and does not require retraction of adjacent organs.1 (-) 3 We have performed several cases of robot-assisted PRA using single-port access for small adrenal tumors. This multimedia article introduces the detailed methods and preliminary results of this procedure. METHODS: Five patients underwent single-port robot-assisted PRA between March 2010 and June 2011 at our institution. During the procedure, patients were placed in a prone jackknife position with their hip joints bent at a right angle (Fig. 1). A 3 cm transverse skin incision was made just below the lowest tip of the 12th rib (Fig. 2), and the Glove port (Nelis, Kyung-gi, Korea) was placed through the skin incision while maintaining pneumoretroperitoneum (Fig. 3). CO2 was then insufflated to a pressure of 18 mm Hg to create an adequate working space. A 10 mm robotic camera with a 30-degree up view was placed at the center of the incision through the most cephalic portion of the Glove port. A Maryland dissector or Prograsp forceps (Intuitive Surgical, Inc., Sunnyvale, CA) was placed on the medial side of the incision, and Harmonic curved shears (Intuitive Surgical) were placed on the lateral side of the incision (Fig. 4). Using the Maryland dissector and the harmonic curved shears, the Gerota fascia is opened, perinephric fat is dissected, and the kidney upper pole is mobilized to expose the adrenal gland (Fig. 5). Gland dissection starts with lower margin detachment from the upper kidney pole in a lateral to medial direction (Fig. 6). After dissecting the adrenal gland from surrounding adipose tissue and medial isolation of the adrenal central vein, the vessel is ligated with a 5 mm hemolock clip (Fig. 7). Patient clinicopathologic data were analyzed retrospectively. RESULTS: The mean patient age was 56.6 ± 8.7 (range, 47-69) years. Right and left side approaches were used in two and three patients, respectively. All cases were adrenal cortical adenoma. The mean tumor size was 1.48 ± 0.28 (range, 1.0-1.7) cm. The mean surgery duration (skin to skin) was 159.4 ± 57.6 (range, 103-245) minutes, and the mean estimated blood loss was 46.0 ± 56.8 (range, 5-120) ml. The average time to oral intake and postoperative hospital stay were 0.65 ± 0.11 (range, 0.54-0.79) days and 4.0 ± 2.23 (range, 3-8) days, respectively. There were no conversions to open surgery or postoperative compli- cations. DISCUSSION: Some trials of minimally invasive single-access surgery of the adrenal gland have recently been performed.4 (,) 5 However, these new techniques have several limitations as a result of restrictions on instrumentation movement because of the small access ports used and relatively low-quality images produced. The recent introduction of the da Vinci S surgical robot system (Intuitive Surgical) to endoscopic surgery has improved instrumental dexterity and provided the surgeon with an ergonomically designed operating system. This system is also potentially safer and more meticulous in performing operations than endoscopic procedures as a result of a 3-D, magnified, stable operative view.6 (,) 7 The advantages of the da Vinci S surgical robot system and the numerous benefits of the posterior retroperitoneal approach motivated us to utilize single-port robot-assisted PRA. The primary selection criteria were small tumor size and a minimal amount of periadrenal fatty tissue because robot-assisted PRA using single-port access provides a small operative space, which causes manipulation problems when tumors are large. To ensure the safe application of these new techniques, we recommend that novice surgeons begin using single-port robot-assisted PRA for smaller tumors < 2 cm in patients with a body mass index of < 30 kg/m(2), gradually extending the size and body mass index as they accumulate experience. Although robot-assisted PRA using single-port access could not be compared with the other robotic adrenalectomy techniques in this study, the potential advantages of this approach compared to conventional robot-assisted transperitoneal adrenalectomy include a reduction in postoperative ileus, bacterial contamination, and intestinal complications because the peritoneal cavity is not opened, in addition to a reduction in postoperative pain because of its minimally invasive nature. CONCLUSIONS: Our initial experiences with robot-assisted PRA using single-port access assured us of its safety and feasibility for the resection of small adrenal tumors. Although single-port robot-assisted PRA appears to be safe and feasible, further experience and research is required to optimize patient selection criteria and verify its advantages over the traditional three-incision PRA technique.ope

A comparative study of the surgical outcomes of robotic and conventional open modified radical neck dissection for papillary thyroid carcinoma with lateral neck node metastasis

BACKGROUND: Several endoscopic modified radical neck dissections (MRND) have been conducted since the introduction of the endoscopic technique to thyroid surgery with the aim of avoiding a long cervical scar. Furthermore, the recent introduction of surgical robotic systems has increased the precision of endoscopic techniques. The aim of this study was to evaluate and compare the early surgical outcomes of robotic and conventional open MRND for papillary thyroid carcinoma (PTC) with lateral neck node metastasis (LNM). METHODS: From January 2009 to May 2010, 165 patients with PTC underwent bilateral total thyroidectomy with central compartment neck dissection and ipsilateral MRND. Of these patients, 56 formed the robotic procedure group (RG) and 109 the conventional open procedure group. These two groups were retrospectively compared with respect to their clinicopathological characteristics, early surgical outcomes, and surgical completeness. RESULTS: The operative time was longer, mean tumor size was smaller, mean age was lower, and disease stage was earlier in the RG. However, mean numbers of retrieved lymph nodes were similar in the two groups, and mean hospital stay after surgery was shorter in the RG. Furthermore, complication rates were similar in the two groups, and there was no statistical difference in postoperative Tg levels between the groups. CONCLUSIONS: Robotic MRND was found to be similar to conventional open MRND in terms of early surgical outcomes and surgical completeness but leaves no scar on the neck area. Robotic MRND can be viewed as an acceptable alternative method in low-risk PTC with LNM.ope