Mimicking facial structures for a robotic head requires integration of multiple structural and mechanical parameters, design, synthesis and control of muscle actuation, architecture of the linkages between actuation points within skin, and implementation of the deformation matrix with respect to global skull coordinates. In this dissertation, humanoid faces were designed and fabricated to investigate all the parameters mentioned above. A prototype face and neck was developed using servo motors and extensively characterized. In this prototype, a neck mechanism was designed using a four bar mechanism to achieve nodding and turning motions. The modular neck prototype simplifies the assembly and statically in equilibrium and hence demands less torque from the cost-effective RC servo motor. The mechanism was critically investigated for dynamic performance and it was found out that RC servo based robotic head requires a PD external controller to overcome inherent overshoot. The servo based robotic head was analyzed for design and control of anchor, architecture of linkages between actuation points within skin, and deformation matrix with respect to global coordinate for creating specific expressions. A functional relationship between deformation vector of facial control points and actuator parameter, skin elasticity and angular position of actuator was derived. The developed analysis method is applicable to any rotary actuator technology utilized for facial expressions and takes into account the skin stiffness. The artificial skin materials for facial expression were synthesized using platinum-cured silicone elastomeric material (Reynolds Advanced Materials Inc.) with base consisting of mainly polyorganosiloxanes, amorphous silica and platinum-siloxane complex compounds. Systematic incorporation of porosity in this material was found to lower the force required to deform the skin in the axial direction. The performance of the servo motor based face was quite realistic but it suffers from the drawback of large power consumption, bulky, heavy, and limited functionality. Thus, significant effort was made in developing a Biometal fiber and Flexinol shape memory alloy actuator (SMA) based biped mountable baby head facial structure which resembles the form and functionality of a human being. SMAs were embedded inside a skull and connected to elastomeric skin at control points. An engineered architecture of skull was fabricated that incorporates all the muscles with their 35 routine pulleys, two fire wire CMOS cameras that serve as eyes, and a battery powered microcontroller base driving circuit within the total dimensions of 140 mm x 90 mm x 110 mm. The driving circuit was designed such that it can be easily integrated with biped and processed in real-time. The humanoid face with 12DOF was mounted on the body of DARwIn (Dynamic Anthropomorphic Robot with Intelligence) robot which has 21 DOF resulting in a total of 33 DOF system. Characterization results on the face and associated design issues are described that provide pathways for developing human-like facial anatomy. Numerical simulation using Simulink was conducted to assess the performance of a prototypic robotic face mainly focusing on jaw movement. A graphical method “Graphical Facial Expression Analysis and Design (GFEAD)” was developed that can be used to allocate the sinking points on robotic head. The method assumes that the origin of the action units are known prior and the underlying criterion in the design of faces being deformation of a soft elastomeric skin through tension in anchoring wires attached on one end to the sinking point and on the other to the actuator. Experimental characterization on a prototyping humanoid face was performed to validate the model and demonstrate the applicability on a generic platform. During characterization of the SMA based face, it was found that the currently available artificial muscle technologies do not meet the entire requirement for being embedded in the skin and provide the required strain rate, maximum strain, blocking force, response time and energy density. Thus an effort was made to develop conducting polymer based artificial muscles which can meet the metrics of human muscle. Composite stripe and zigzag actuators consisting of a sandwich structure polypyrrole /poly(vinylidene difluoride) (PPy/PVDF) were synthesized using potentiodynamic film growth on gold electrodes. The synthesis was done from an aqueous solution containing tetrabutylammonium Perchlorate (TBAP) and pyrrole by polymerization at room temperature. For depositing thin PPy films and thereby minimizing the response time, an experimental optimization of the deposition conditions was performed. The number of current-potential (potentiodynamic) growth cycles and the thickness of the deposited PPy film were highly correlated in the initial stages of polymer film growth. Strip actuator of size 11 x 5 mm2 with 63μM exhibited a deflection of 3mm under 1V DC voltage and 2mm deflection under 8V AC voltage at 0.5 Hz. It was found that three-segment zigzag actuator of segment length 15x2.5mm and thickness 63μM amplifies the displacement by 1.5 times. A study was also conducted on the synthesis and characterization of thick and thin film polypyrrole (PPy) – metal composite actuators. The fabrication method consisted of three steps based upon the approach proposed by Ding et al.: (i) winding the conductive spiral structure around the platinum (Pt)-wire core, (ii) deposition of PPy film on the Pt-wire core, and (iii) removal of the Pt-wire core. This approach yielded good performance from the synthesized actuators, but was complex to implement due to the difficulty in implementing the third step. To overcome the problem of mechanical damage occurring during withdrawal of Pt-wire, the core was replaced with a dispensable gold coated polylactide fiber that could be dissolved at the end of deposition step. Experimental results indicate that thin film actuators perform better in terms of response time and blocking force. A unique muscle-like structure with smoothly varying cross-section was grown by combining layer by layer deposition with changes in position and orientation of the counter electrode in reference to the working electrode. Synthesis of polypyrrole–metal coil was conducted in aqueous solution containing 0.25 M Pyrrole, 0.10 M TBAP and 0.50 M KCl. The actuator consisted of a single layer of platinum winding on a core substrate. Electrochemical characterization for free strain and blocking stress was conducted 0.1 M TBAP solution and a 6% free strain was obtained at an applied potential of 6V DC after 80 s stimulation time. The blocking stress 18 kPa was estimated by extrapolating the strain magnitude on stress-strain diagram. For axial type actuator with coil winding, a generalized governing equation for the electrochemical stress generated from polypyrrole–metal coil which accommodates the effect of magnetic field due to winding was proposed and numerically studied. It was considered as insightful modeling. / Ph. D.

O processo de coloração de cabelos é um dos métodos de tintura mais antigos. No século XIX, iniciou-se a produção de corantes sintéticos, a partir do desenvolvimento da pfenilenodiamina (PPD). Os corantes de cabelo são classificados de acordo com seu mecanismo de ação. Os corantes permanentes são classificados por mecanismos oxidativos, enquanto os corantes diretos colorem a fibra capilar por mecanismos não oxidativos. A investigação sobre os possíveis danos á saúde humana, que podem ser resultantes da exposição de corantes de cabelos, têm sido um tema de enorme desafio para a comunidade cientifica. Particularmente, devido à enorme discrepância dos estudos epidemiológicos e estudos que empregam metodologias in vitro. Neste trabalho, foram investigadas a capacidade citotóxica de um composto representante de cada classe de tinturas de cabelo, um corante temporário (Basic Yellow 57 (BY57), um semi-temporário (Basic Red 51(BR51) e um ingrediente permanente p-fenilinodiamina (PPD) em linhagens de células de pele humana. As linhagens normais da pele humana estudadas foram os queratinócitos imortalizados humanos (HaCaT) e fibroblastos primários, utilizou-se também melanoma SK-Mel-103. Posteriormente, após caracterização do corante mais tóxico, foi investigado o tipo de morte celular, as possíveis alterações destes compostos no ciclo celular, a capacidade de geração de espécies reativas de oxigênio (EROs) e aplicação em cultura tridimensional de pele artificial. Posteriormente, foi avaliada a capacidade de cada corante em induzir estresse oxidativo em queratinócitos humanos (HaCaT), que são a primeira via de exposição de corantes de cabelos. Em seguida, o corante elegido mais tóxico foi aplicado em pele humana provenientes de cirurgia. Finalmente, o potencial de mutagenicidade dos corantes BY57 e BR51 foram avaliados. / The process involving hair dyes is one of the oldest methods of coloring. The use of synthetic hair dyes started in the nineteenth century, after the development of p-phenylenodiamine (PPD). The hair dyes are classified according to their mechanism of action. The permanent hair dyes are classified by oxidative mechanisms, while direct dyes color the hair fiber by non-oxidative mechanisms. Research regarding the potential damage of hair dyes to human health has been an enormous challenge for the scientific community. Particularly due to the large discrepancy of epidemiological studies involving in vitro methodologies. In this study, we evaluated the cytotoxic potential of a compound representative from each of the class of hair dyes, a temporary dye (Basic Yellow 57 (BY57), a semi temporary (Basic Red 51 (BR51) and a permanent hair dyes p-phenylenodiamine (PPD) in human skin cells. The studied skin cell lines where, immortalized human keratinocytes (HaCaT) primary fibroblasts, we also used melanoma SK-Mel-103. Subsequently, after characterization of the most toxic dye, we investigated specific mechanisms of cell death, changes in cell cycle and the ability to generate reactive oxygen species (ROS) followed by the evaluation of three-dimensional artificial skin. In addition, we assessed the ability of each dye in inducing oxidative stress in immortalized human keratinocytes (HaCaT) this is the primary route of exposure of hair dyes. Then, the most toxic compound was tested in human skin explants. Finally the mutagenic potential of the dyes BY57 and BR51 were evaluated.

O surgimento das matrizes de regeneração dérmica nas duas últimas décadas permitiu um grande avanço no tratamento tanto das queimaduras agudas como das sequelas. No entanto, ainda há carência de informações sobre a relação entre os resultados clínicos e o que ocorre no tecido com cada tipo de matriz. O objetivo deste estudo foi avaliar prospectivamente os aspectos clínicos quanto à qualidade de pele, escala de Vancouver e POSAS, função e retração da área tratada e os aspectos histológicos na microscopia de luz e eletrônica, com o uso de duas matrizes de regeneração dérmica, ambas de colágeno bovino, uma de duas camadas, recoberta com lâmina de silicone e outra sem. Vinte e quatro pacientes, sorteados 12 em cada grupo, tiveram suas retrações cicatriciais secundárias à queimaduras tratadas em duas cirurgias, a primeira de liberação da retração e colocação da matriz e a segunda, colocação do auto enxerto de pele; em ambas as cirurgias foi utilizado o curativo de pressão negativa. As avaliações da escala de Vancouver e medidas da retração da área foram realizadas no pré-operatório, 1, 3, 6 e 12 meses e a escala de POSAS e avaliação funcional no pré-operatório e aos 12 meses. As biópsias foram colhidas no pré-operatório, no dia da colocação do enxerto de pele, 12 dias, 2, 6 e 12 meses após o enxerto. A avaliação clínica mostrou retração de todas as áreas tratadas, melhora da qualidade da pele e funcional em todos os pacientes. A matriz com silicone, mostrou superioridade dos resultados quanto a qualidade da pele, função e menor retração da área tratada. A análise histológica mostrou o crescimento de tecido conjuntivo denso idêntico ao tecido cicatricial original, sem diferenças entre as matrizes e que não se assemelha à derme normal. Também não foi observada diferença no diâmetro das fibrilas de colágeno do tecido neoformado, a pele normal e a cicatriz / The advent of dermal regenerate templates has fostered major advances in the treatment of acute burns and their sequelae, in the last two decades. Both data on morphological aspects of the newly-formed tissue, and clinical trials comparing different templates, are still lacking. The goal of this study was to prospectively analyze the outcome of patients treated with two of the existing templates, followed by thin skin autograft. They are both made of bovine collagen, one includes a superficial silicone layer. Surgery was performed on patients with impaired mobility resulting from burn sequelae (n = 12 per template). Negative pressure therapy was applied post-surgically; patients were monitored for 12 months. Data on scar skin quality (Vancouver and POSAS evaluation scales), rate of joint mobility recovery, and graft contraction were recorded; as well as morphological analyses at light microscopical and ultrastructural levels. Improvement in mobility and skin quality were demonstrated along with graft contraction, in all patients. The silicone-coupled template showed the best performance in all aspects. There was sub epidermal growth of dense connective tissue, indistinguishable from the original scars in both templates. The formation of tissue resembling normal dermis was not detected in any of the cases. Likewise, the ultrastructural analysis showed the same architecture of the connective tissue among the template scars and the original scar. No difference was detected when the collagen fibril diameters of the normal skin and of the scars (original and of the two templates) were compared

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

O processo de coloração de cabelos é um dos métodos de tintura mais antigos. No século XIX, iniciou-se a produção de corantes sintéticos, a partir do desenvolvimento da pfenilenodiamina (PPD). Os corantes de cabelo são classificados de acordo com seu mecanismo de ação. Os corantes permanentes são classificados por mecanismos oxidativos, enquanto os corantes diretos colorem a fibra capilar por mecanismos não oxidativos. A investigação sobre os possíveis danos á saúde humana, que podem ser resultantes da exposição de corantes de cabelos, têm sido um tema de enorme desafio para a comunidade cientifica. Particularmente, devido à enorme discrepância dos estudos epidemiológicos e estudos que empregam metodologias in vitro. Neste trabalho, foram investigadas a capacidade citotóxica de um composto representante de cada classe de tinturas de cabelo, um corante temporário (Basic Yellow 57 (BY57), um semi-temporário (Basic Red 51(BR51) e um ingrediente permanente p-fenilinodiamina (PPD) em linhagens de células de pele humana. As linhagens normais da pele humana estudadas foram os queratinócitos imortalizados humanos (HaCaT) e fibroblastos primários, utilizou-se também melanoma SK-Mel-103. Posteriormente, após caracterização do corante mais tóxico, foi investigado o tipo de morte celular, as possíveis alterações destes compostos no ciclo celular, a capacidade de geração de espécies reativas de oxigênio (EROs) e aplicação em cultura tridimensional de pele artificial. Posteriormente, foi avaliada a capacidade de cada corante em induzir estresse oxidativo em queratinócitos humanos (HaCaT), que são a primeira via de exposição de corantes de cabelos. Em seguida, o corante elegido mais tóxico foi aplicado em pele humana provenientes de cirurgia. Finalmente, o potencial de mutagenicidade dos corantes BY57 e BR51 foram avaliados. / The process involving hair dyes is one of the oldest methods of coloring. The use of synthetic hair dyes started in the nineteenth century, after the development of p-phenylenodiamine (PPD). The hair dyes are classified according to their mechanism of action. The permanent hair dyes are classified by oxidative mechanisms, while direct dyes color the hair fiber by non-oxidative mechanisms. Research regarding the potential damage of hair dyes to human health has been an enormous challenge for the scientific community. Particularly due to the large discrepancy of epidemiological studies involving in vitro methodologies. In this study, we evaluated the cytotoxic potential of a compound representative from each of the class of hair dyes, a temporary dye (Basic Yellow 57 (BY57), a semi temporary (Basic Red 51 (BR51) and a permanent hair dyes p-phenylenodiamine (PPD) in human skin cells. The studied skin cell lines where, immortalized human keratinocytes (HaCaT) primary fibroblasts, we also used melanoma SK-Mel-103. Subsequently, after characterization of the most toxic dye, we investigated specific mechanisms of cell death, changes in cell cycle and the ability to generate reactive oxygen species (ROS) followed by the evaluation of three-dimensional artificial skin. In addition, we assessed the ability of each dye in inducing oxidative stress in immortalized human keratinocytes (HaCaT) this is the primary route of exposure of hair dyes. Then, the most toxic compound was tested in human skin explants. Finally the mutagenic potential of the dyes BY57 and BR51 were evaluated.

O surgimento das matrizes de regeneração dérmica nas duas últimas décadas permitiu um grande avanço no tratamento tanto das queimaduras agudas como das sequelas. No entanto, ainda há carência de informações sobre a relação entre os resultados clínicos e o que ocorre no tecido com cada tipo de matriz. O objetivo deste estudo foi avaliar prospectivamente os aspectos clínicos quanto à qualidade de pele, escala de Vancouver e POSAS, função e retração da área tratada e os aspectos histológicos na microscopia de luz e eletrônica, com o uso de duas matrizes de regeneração dérmica, ambas de colágeno bovino, uma de duas camadas, recoberta com lâmina de silicone e outra sem. Vinte e quatro pacientes, sorteados 12 em cada grupo, tiveram suas retrações cicatriciais secundárias à queimaduras tratadas em duas cirurgias, a primeira de liberação da retração e colocação da matriz e a segunda, colocação do auto enxerto de pele; em ambas as cirurgias foi utilizado o curativo de pressão negativa. As avaliações da escala de Vancouver e medidas da retração da área foram realizadas no pré-operatório, 1, 3, 6 e 12 meses e a escala de POSAS e avaliação funcional no pré-operatório e aos 12 meses. As biópsias foram colhidas no pré-operatório, no dia da colocação do enxerto de pele, 12 dias, 2, 6 e 12 meses após o enxerto. A avaliação clínica mostrou retração de todas as áreas tratadas, melhora da qualidade da pele e funcional em todos os pacientes. A matriz com silicone, mostrou superioridade dos resultados quanto a qualidade da pele, função e menor retração da área tratada. A análise histológica mostrou o crescimento de tecido conjuntivo denso idêntico ao tecido cicatricial original, sem diferenças entre as matrizes e que não se assemelha à derme normal. Também não foi observada diferença no diâmetro das fibrilas de colágeno do tecido neoformado, a pele normal e a cicatriz / The advent of dermal regenerate templates has fostered major advances in the treatment of acute burns and their sequelae, in the last two decades. Both data on morphological aspects of the newly-formed tissue, and clinical trials comparing different templates, are still lacking. The goal of this study was to prospectively analyze the outcome of patients treated with two of the existing templates, followed by thin skin autograft. They are both made of bovine collagen, one includes a superficial silicone layer. Surgery was performed on patients with impaired mobility resulting from burn sequelae (n = 12 per template). Negative pressure therapy was applied post-surgically; patients were monitored for 12 months. Data on scar skin quality (Vancouver and POSAS evaluation scales), rate of joint mobility recovery, and graft contraction were recorded; as well as morphological analyses at light microscopical and ultrastructural levels. Improvement in mobility and skin quality were demonstrated along with graft contraction, in all patients. The silicone-coupled template showed the best performance in all aspects. There was sub epidermal growth of dense connective tissue, indistinguishable from the original scars in both templates. The formation of tissue resembling normal dermis was not detected in any of the cases. Likewise, the ultrastructural analysis showed the same architecture of the connective tissue among the template scars and the original scar. No difference was detected when the collagen fibril diameters of the normal skin and of the scars (original and of the two templates) were compared