Dragon Skin Research Articles

Validation of a Simulation Model for Laparoscopic Myomectomy Developed with 3D-Printed Molds

PURPOSE: To develop a model that can be used by Ob-Gyn residents when performing simulation for laparoscopic myomectomy. BACKGROUND: Laparoscopic myomectomy (LM) is a challenging procedure encountered by Ob-Gyn residents during residency training. Limited commercial simulation products exist but are cost-prohibitive for consistent use. METHODS: Uterine and fibroid molds were generated using Pixelogic® Z-brush design software and printed from a 3D printer using polylactic acid filament. Smooth-On® Dragon Skin silicone of varying densities was used for the uterus and fibroids. The model consisted of a uterine body with four fundal subserosal fibroids – two placed anteriorly and two placed posteriorly—fallopian tubes, and round ligaments. Residents evaluated the model and its effectiveness in simulating LM upon simulation completion. RESULTS: Five uterine models with four fibroids each were constructed for a total cost of $318 (printed molds, silicone, and pigment); replacement models cost $30 (silicone and pigment only). The model functioned well within the trainer box using surgical instruments and suture; however, the base of the fibroid adhered to the myometrium making excision of the entire specimen difficult. All residents (N=13) used the model. Residents felt the model was realistic (4/5), helps develop skills needed for LM (4.5/5), and will increase resident competency in laparoscopy (4.8/5). DISCUSSION: Our model provides a realistic simulation of LM at low cost. One model can be used by up to four residents. We can repair previously used models with silicone allowing them to be reused. We have updated the model to decrease fibroid adherence to the myometrium and facilitate complete excision.

Silicones for Stretchable and Durable Soft Devices: Beyond Sylgard-184.

This paper identifies and characterizes silicone elastomers that are well-suited for fabricating highly stretchable and tear-resistant devices that require interfacial bonding by plasma or UV ozone treatment. The ability to bond two or more pieces of molded silicone is important for creating microfluidic channels, chambers for pneumatically driven soft robotics, and other soft and stretchable devices. Sylgard-184 is a popular silicone, particularly for microfluidic applications. However, its low elongation at break (∼100% strain) and moderate tear strength (∼3 N/mm) make it unsuitable for emerging, mechanically demanding applications of silicone. In contrast, commercial silicones, such as Dragon Skin, have excellent mechanical properties yet are difficult to plasma-bond, likely because of the presence of silicone oils that soften the network yet migrate to the surface and interfere with plasma bonding. We found that extracting silicone oligomers from these soft networks allows these materials to bond but only when the Shore hardness exceeds a value of 15 A. It is also possible to mix highly stretchable silicones (Dragon Skin and Ecoflex) with Sylgard-184 to create silicones with intermediate mechanical properties; interestingly, these blends also only bond when the hardness exceeds 15 A. Eight different Pt-cured silicones were also screened; again, only those with Shore hardness above 15 A plasma-bond. The most promising silicones from this study are Sylgard-186 and Elastosil-M4130 and M4630, which exhibit a large deformation (>200% elongation at break), high tear strength (>12 N/mm), and strong plasma bonding. To illustrate the utility of these silicones, we created stretchable electrodes by injecting a liquid metal into microchannels created using such silicones, which may find use in soft robotics, electronic skin, and stretchable energy storage devices.

Characterization and optimization of flexible dual mode sensor based on Carbon Micro Coils

Carbon Microcoils (CMCs) is a 3D helical micro structure grown via a chemical vapor deposition process. It is noted that composites in which CMCs are embedded in polymer matrixes, called CMC sheets, experience a drastic change of electrical impedance depending on the proximity and contact of external objects. In this paper, a dual functional sensor, that is, tactile and proximity sensor fabricated with CMC/silicone composite is presented to demonstrate the advanced characteristics of CMCs sheets. Characteristics of sensor responses depending on CMC compositions are investigated and optimal conditions are determined. The candidates of polymer matrices are also investigated. As the results, the CMC sheet consisting of Ecoflex 30, CMC 30 , and multiwall carbon nanotubes 1 shows the most appropriate tactile sensing characteristics with more than 1 mm of thickness. The proximity sensing capability is the maximum when the 1.5 CMC content is mixed with Dragon skin 30 silicone substrate. Finally, multiple target objects are recognized with the results and their feasibilities are experimentally validated.

Characteristics of Frozen Yoghurt Enriched with Red Dragon Fruit Skin Extracts (Hylocereus polyrhizus)

The composition of the dragon fruit skin with fruit has a weight of 30-35% of the fruit weight and has not been widely utilized. Previous studies have suggested that red dragon fruit skin extracts with water solvent contain 1.1 mg / 100 ml anthocyanin. The content of anthocyanin can function lower cholesterol content in blood, besides red dragon fruit skin contains fiber about 46,7% which is very good for health. This study aims to determine the chemical characteristics of frozen yogurt red dragon skin fruit to antioxidant levels, fiber content, pH, Total acid content and frozen yogurt melting time. The design of the research was Randomized Complete Design (RAL) of 1 factor, which was treated as red dragon skin fruit extract, consisting of 4 treatment levels: 0%, 25%, 35%, and 45%. The results showed that the addition of red dragon fruit extract increased antioxidant levels ranging from 4.00 to 12.25%, crude fiber content ranged from 1.037 to 1.625%, total acid ranged from 0.73 to 1.14%, and decreased the pH value of 5, 48 - 4.39 and has a melting time of frozen yogurt 17.20 - 22.88 minutes.

EFFECTS OF RED DRAGON FRUIT (Hylocereus polyrhizus) SKIN EXTRACT ON LEAD ACETATE TOXICITY IN THE MORPHOLOGY OF Balb/c MICE (Mus musculus) SPERMATOZOA

Red dragon fruit skin extract is used as an antioxidant to lead acetate toxicity. This study aimed to prove the difference in morphology of mice testicular spermatozoa exposed to lead acetate. Twenty-five mice were divided into 5 groups (5 mice per group). K- group was the control group without lead acetate and dragon fruit skin extract administration, K + group was treated with 8 mg/KgBW lead acetate administration for 14 days, P1 group was treated with the administration of 8 mg/KgBW lead acetate for 14 days + 250 mg/kgBW red dragon fruit skin extract for 21 days, P2 group was treated with the administration of 8 mg/KgBW lead acetate for 14 days + 500 mg/kgBW red dragon fruit skin extract for 21 days, and group P3 was a treatment group with the administration of 8 mg/KgBW lead acetate for 14 days + 1000 mg/kgBW red dragon fruit extract for 21 days. The results showed that there was significant difference (P<0.05) in normal sperm morphology among K-, K +, P1, P2, and P3. In conclusion, the administration of red dragon skin extract at a dose of 500 mg/kgBW (P2) is the optimal one which can be used as therapy to increase motility, morphology, and concentration of mice spermatozoa exposed to lead acetate.

Comparison of different soft grippers for lunch box packaging

Automating the lunch box packaging is a challenging task due to the high deformability and large individual differences in shape and physical property of food materials. Soft robotic grippers showed potentials to perform such tasks. In this paper, we presented four pneumatic soft actuators made of different materials and different fabrication methods and compared their performances through a series of tests. We found that the actuators fabricated by 3D printing showed better linearity and less individual differences, but showed low durability compared to actuators fabricated by traditional casting process. Robotic grippers were assembled using the soft actuators, and grasping tests were performed on soft paper containers filled with food materials. Results suggested that grippers with softer actuators required lower air pressure to lift up the same weight and generated less deformation on the soft container. The actuator made of casting process with Dragon Skin 10 material lifted the most weight among different actuators.

Multimodal 3D cancer-mimicking optical phantom.

Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing various aspects of optical systems, including for evaluating new probe designs, characterizing the diagnostic potential of new technologies, and assessing novel image processing algorithms prior to validation in real tissue. We introduce and characterize the use of a new material, Dragon Skin (Smooth-On Inc.), and fabrication technique, air-brushing, for fabrication of a 3D phantom that mimics the appearance of a real organ under multiple imaging modalities. We demonstrate the utility of the material and technique by fabricating the first 3D, hollow bladder phantom with realistic normal and multi-stage pathology features suitable for endoscopic detection using the gold standard imaging technique, white light cystoscopy (WLC), as well as the complementary imaging modalities of optical coherence tomography and blue light cystoscopy, which are aimed at improving the sensitivity and specificity of WLC to bladder cancer detection. The flexibility of the material and technique used for phantom construction allowed for the representation of a wide range of diseased tissue states, ranging from inflammation (benign) to high-grade cancerous lesions. Such phantoms can serve as important tools for trainee education and evaluation of new endoscopic instrumentation.

섬(Island) 구조로 이루어진 강성도 국부변환 신축성 기판의 변형 거동

In order to develop stretchable substrate technology for stretchable devices, locally stiffness-variant stretchable substrates were processed with two polydimethylsiloxane elastomers of different stiffnesses and their deformation behavior was characterized. Low-stiffness substrate matrix and embedded high-stiffness island of the stretchable substrate were formed by using Dragon Skin 10 of the elastic modulus of 0.09 MPa and Sylgard 184 of the elastic modulus of 2.15 MPa, respectively. A stretchable substrate was fabricated to a configuration of 6.5 cm length, 0.4 cm thickness, and 2.5 cm width. The elastic modulus of a stretchable substrate was increased from 0.09 MPa to 0.13~0.33 MPa by embedding a Sylgard 184 island of 1 cm width and 1~6 cm length into the center part of the Dragon Skin 10 substrate matrix. The elastic modulus of a stretchable substrate was improved to 0.16~0.2 MPa by embedding a Sylgard 184 island of 4 cm length and 0.5~1.5 cm width and to 0.1421~0.154 MPa by embedding a Sylgard 184 island of 2 cm length and 0.5~1.5 cm width. With increasing the tensile strain of a stretchable substrate, deformation restriction of the locally stiffness-variant Sylgard 184 island was further enhanced due to substantial increase in the strength difference between Sylgard 184 and Dragon 10 at large strain.

신축성 전자패키징용 강성도 국부변환 polydimethylsiloxane 기판의 탄성계수

In order to apply to stretchable electronics packaging, locally stiffness-variant stretchable substrates consisting of island structure were fabricated by combining two polydimethylsiloxane elastomers of different stiffnesses and their elastic moduli were characterized as a function of the width of the high-stiffness island. The low-stiffness substrate matrix and the embedded high-stiffness island of the stretchable substrate were formed by using Dragon Skin 10 of the elastic modulus of 0.09 MPa and Sylgard 184 of the elastic modulus of 2.15 MPa, respectively. A stretchable substrate was fabricated to be a configuration of 6.5-cm length, 0.4-cm thickness, and 2.5-cm width, in which a high-stiffness Sylgard 184 island, of 4-cm length, 0.2-cm thickness, and 0.5~1.5-cm width, was embedded. The elastic modulus of a stretchable substrate was increased from 0.09 MPa to 0.16 MPa by incorporating the Sylgard 184 island of 0.5-cm width to Dragon Skin 10 substrate matrix. The elastic modulus was further improved to 0.18 MPa and 0.2 MPa with increasing the Sylgard 184 island width to 1.0 cm and 1.5 cm, which were in good agreement with values estimated by combining the Voigt structure of isostrain and the Reuss structure of isostress.

Use of 3-Dimensional Printing Technology and Silicone Modeling in Surgical Simulation: Development and Face Validation in Pediatric Laparoscopic Pyeloplasty

Pediatric laparoscopy poses unique training challenges owing to smaller workspaces, finer sutures used, and potentially more delicate tissues that require increased surgical dexterity when compared with adult analogs. We describe the development and face validation of a pediatric pyeloplasty simulator using a low-cost laparoscopic dry-laboratory model developed with 3-dimensional (3D) printing and silicone modeling. The organs (the kidney, renal pelvis, and ureter) were created in a 3-step process where molds were created with 3D modeling software, printed with a Spectrum Z510 3D printer, and cast with Dragon Skin 30 silicone rubber. The model was secured in a laparoscopy box trainer. A pilot study was conducted at a Canadian Urological Association meeting. A total of 24 pediatric urology fellows and 3 experienced faculty members then assessed our skills module during a minimally invasive surgery training course. Participants had 60 minutes to perform a right-side pyeloplasty using laparoscopic tools and 5-0 VICRYL suture. Face validity was demonstrated on a 5-point Likert scale. The dry-laboratory model consists of a kidney, a replaceable dilated renal pelvis and ureter with an obstructed ureteropelvic junction, and an overlying peritoneum with an inscribed fundamentals of laparoscopic surgery pattern-cutting exercise. During initial validation at the Canadian Urological Association, participants rated (out of 5) 4.75 ± 0.29 for overall impression, 4.50 ± 0.41 for realism, and 4.38 ± 0.48 for handling. During the minimally invasive surgery course, 22 of 24 fellows and all the faculty members completed the scoring. Usability was rated 4 or 5 by 14 participants (overall, 3.6 ± 1.22 by novices and 3.7 ± 0.58 by experts), indicating that they would use the model in their own training and teaching. Esthetically, the model was rated 3.5 ± 0.74 (novices) and 3.3 ± 0.58 (experts). We developed a pediatric pyeloplasty simulator by applying a low-cost reusable model for laparoscopic training and skills acquisition. The model's usability, realism, and feel are good, it can be imaged under common modalities, and it shows promise as an educational tool.

Variable stiffness outer sheath with “Dragon skin” structure and negative pneumatic shape-locking mechanism

Natural orifice transluminal endoscopic surgery (NOTES) offers the possibility of surgery without visible scars. To overcome the limitations of NOTES, we developed a novel surgical device called the rigid and flexible outer sheath with multi-piercing surgery (MPS). This sheath can switch between flexible and rigid modes using a novel "Dragon skin" structure and a negative pneumatic shape-locking mechanism. In addition, it has an integrated bending structure that enables it to flex in four directions at the distal end. The insertion part of the prototype is 575mm long with a 20 mm outer diameter. The rigid and flexible shaft is separated into two parts. The primary and secondary shape-locking shafts are 300 and 200 mm long, respectively. The two parts of shape-locking shaft can be locked independently, including both being locked simultaneously. In addition, the model was equipped with one 7- and 1.7-mm-diameter, and three 3-mm-diameter working channels. When the sheath approaches the target, the surgeon locks the shape and then easily inserts flexible instruments through the path created by the sheath. In this study, we evaluated the stiffness of the prototype. Furthermore, an in vivo partial gastrectomy experiment was also performed. The experimental results regarding the shape property suggest that the rigidity of the shaft was considerably increased using this mechanism. An in vivo partial gastrectomy experiment performed using a swine was successfully performed using the outer sheath for assistance. The outer sheath was inserted through a percutaneous route during the in vivo experiment. The evaluation results show that the advanced outer sheath system has great promise for solving access and stability problems with NOTES.

Surface roughness and geometrical characterization of ultra-thick micro moulds for ceramic micro fabrication using soft lithography

Ceramic micro fabrication using soft lithography is a well-known technique used to pattern high-aspect-ratio microstructures. The quality of the pattern highly relies on the quality of the moulds. This paper describes the surface roughness and geometrical characterization of soft lithography technique for the fabrication of ceramic micro components. Effects of patterning materials and methods on the produced geometry, repeatability and surface roughness were studied and a comparative study was performed for the optimization process. UV lithography of BPR100 and SU-8 and deep reactive ion etching are the methods for fabricating the master mould. In addition, polydimethylsiloxane and Dragon Skin elastomeric have been used in the fabrication of the soft moulds. Mould geometry was inspected using SEM images while surface roughness was measured using stereo imaging. The results show that the maximum obtained thicknesses are 1,000, 250 and 500 μm for SU-8, BPR100 and DRIE moulds. In addition, their surface roughness values are higher than the SU-8. On the other hand, Dragon Skin shows demoulding problems despite it has smoother surface than PDMS mould.

The Use of a Multi-Component Medical Model in the Separation of Omphalopagus Conjoined Twins

INTRODUCTION: The reconstructive challenge with omphalopagus conjoined twins lies not only with the division of shared abdominal organs but also with the closure of what is often a significant skin and abdominal wall defect. The separation procedure requires meticulous planning to ensure an optimal reconstructive design. Preoperative planning of complex reconstructive endeavors has increasingly benefited from the use of commercially available medical models. Custom multi-component medical sculpture can further enhance the effective and functionality of preoperative planning. Purpose We present a case of 19-month-old omphalopagus conjoined twins who underwent surgical separation and abdominal wall reconstruction facilitated by the use a two component medical model. METHODS: A life-size model was cast of omphalopagus conjoined twins, which included a circumferential rendition of the lower thorax and abdomen. The model consisted of a foam core (FlexFoam-iT! X; Smooth-On, Easton, PA) simulating the density of the soft tissue, with a silicone-rubber mixture (Dragon Skin Q; Smooth-On, Easton, PA) to simulate the natural elasticity of skin. The interface between the foam and the silicone/rubber layer was easily detachable, allowing the effect of undermining to be simulated. Tissue expanders at different stages of enlargement, were sculpted onto the model to determine the amount of expansion required. The reconstructive design elaborated on the model was utilized during the 20-hour operation that resulted in the successful twins' separation. CONCLUSION: Using a two-component model, reconstructive surgery was precisely and easily simulated during varying degrees of tissue expansion. The effects of skin elasticity and surgical undermining were accurately reproduced. With accurate models available in the laboratory, the reconstructive surgeon is allowed an opportunity to design the best possible flap coverage and ensure maximum efficiency in the operating room. We believe the creation of a customized multi-component medical model enhances presurgical planning capabilities for complex reconstructive endeavors.

Microbial genomics as pursuit of happiness

Microbial genomics as pursuit of happiness