Este trabalho foi apoiado pelo financiamento de arranque da Escola de Engenharia, Virginia Commonwealth University e alguns dispositivos eletrônicos foram preparados nas instalações de microfabricação na Virginia Wright Microelectronics Center. Nós reconhecemos os pesquisadores que fizeram contribuições para o dispositivo e os dados clínicos (Figuras 3 e 5 do presente documento), adquirida a partir do artigo publicado 10. W.-HY graças Yoshiaki Hattori para o, software de gravação de dados feito sob medida.

As experiências para a fabricação do dispositivo, laminação pele, caracterização e mostrado nas Figuras 1, 2, e 4, envolveu duas voluntários todos realizados no Laboratório Bio-nanoengineering interface da Universidade da Virgínia (VCU), Richmond, VA, EUA. Este estudo foi aprovado pelo Institutional Review Board VCU (número de protocolo: HM20001454) e seguiu as diretrizes de pesquisa da Human Research VCU. Os dados do aparelho e clínicas apresentadas nas Figuras 3 e 5 foram adquiridas a partir do artigo publicado em 10 de onde as experiências com pacientes foram conduzidos sob o protocolo (número: STU69718), aprovado pelo Conselho de Revisão Institucional da Universidade Northwestern, Chicago, IL, EUA. Fabrication 1. Dispositivo NOTA: A Figura 2 apresenta ilustrações esquemáticas para o processo global de fabrico. <ol><li> Preparar um substrato portador<ol><li> Cortar uma 3 em silício (Si) para a bolacha nua tamanho desejado da electrónica, utilizando uma lâmina de diamante. NOTA: Cerca de metade Si wafer dá um tamanho ideal para o dispositivo ferida. </li><li> Desengordurar bolacha de Si com acetona e álcool isopropílico (IPA). Lavar a bolacha com água desionizada (Dl) e, em seguida seca com azoto e desidratar numa placa de aquecimento a 110 ° C durante 3 min. </li><li> Preparar 11 g de polidimetilsiloxano (PDMS) com a mistura de 10: 1 razão em volume de base e agente de cura e desgaseificar a mistura numa câmara de vácuo durante uma hora. NOTA: PDMS é usado para uma recuperação padrão seco e transferir a impressão após a microfabricação, que é preferível para o produto químico molhado (acetona) abordagem baseada no estudo anterior 7. </li><li> Rotação revestimento 5 g de uma solução mista de PDMS na bolacha a 3000 rpm durante 1 min e curar completamente numa placa de aquecimento a 150 ° C durante 30 min. </li></ol></li><li> Materiais de Depósito e eletrônica padrão <ol><li> Tratar o PDMS-Coated bolacha com ultravioleta (UV) / ozono, utilizando uma lâmpada de UV (8,9 mW / cm2) durante 3 minutos para tornar a superfície hidrófila. NOTA: A superfície hidrofílica oferece revestimento uniforme de camadas adicionais sobre o PDMS. </li><li> Spincoat poliimida (PI; 2 mL) nas PDMS revestido da bolacha, por pipetagem, a 4.000 rpm durante 1 minuto para formar uma camada de 1,2 mícrons de espessura, pré-cozer numa placa de aquecimento a 150 ° C durante 5 min, e pós- cozer a 250 ° C durante 2 horas. </li><li> Depósito de crómio (Cr), para formar uma camada de 20 nm de espessura e, em seguida, depositar o cobre (Cu), para formar uma camada de 3 micrómetros de espessura usando o feixe de electrões (E-beam) evaporação (pressão de base: ~ 1 x 10 -7 Torr , a pressão de deposição: ~ 1 × 10 -6 Torr, taxa de deposição: 1-5 A / S). Monitorar a espessura da película por deposição a interface do controlador embutido no evaporador. NOTA: A espessa camada de Cu proporciona níveis suficientes de condutividade elétrica nas resistências em microescala do dispositivo e fina camada de Cré usado para promover a adesão entre a PI e Cu. </li><li> Spincoat um fotorresistente (2 ml) com três passos a 900 rpm durante 10 seg, 1.100 rpm, durante 60 s, e 4000 rpm durante 20 segundos e, em seguida, curar numa placa de aquecimento a 75 ° C durante 30 min. NOTA: As etapas sequenciais descritos acima foram utilizados para depositar uma espessa (&gt; 10 um) fotorresistente. </li><li> Alinhe Cu eletrônicos padrões (sensores; fractal projeto &#39;Peano&#39; com 35 mm de largura e interconexões; design de malha serpentina aberto com 50 mm de largura) no centro da lâmina de silício usando um alinhador UV (de energia: 10 mW / sec) com o tempo de exposição de 25 s. NOTA: As estruturas fractais são usados ​​para fornecer capacidade de estiramento mecânico superior, em comparação com apenas 14 sinuosos características. </li><li> Desenvolver o photoresist em um desenvolvedor de base diluída (1: 2 proporção de desenvolvedor e água DI) por um minuto, lave com água DI, e seca com azoto. Inspecione os padrões fractais (Cu e interconexões) usando um microescopo para confirmar o tamanho e característica encontrar quaisquer defeitos de partículas. NOTA: Se houver quaisquer defeitos indesejáveis, em seguida, retire photoresist por lavagem com água acetona / IPA / DI. Após a secagem com azoto, repita os passos a partir de 1.2.4 para 1.2.6. </li><li> Etch a camada de Cu sobre a bolacha de Si por imersão em um produto corrosivo de química húmida para ~ 6 min (10 ml; mistura de persulfato de amónio e água na proporção de 1: 4; taxa de 8 nm / seg etch em 40 ° C), enxaguamento com água DI, e seca com azoto. Inspecione os padrões usando um microscópio para quaisquer padrões sobre-gravados. NOTA: Se os padrões são sobre-gravado, ele pode causar arestas indesejadas dos recursos, o que poderia levar à fratura mecânica durante o manuseio do aparelho e processo de lavagem. Os resultados dos testes anteriores mostraram que mais de ~ 20% sobre-condicionamento dos padrões originais causou os problemas acima mencionados. </li><li> Etch a camada de Cr com gravação iónica reactiva (RIE; pressão: 300 mTorr, potência: 200 W, CF 4 gás: 5 sccm, O 2 gás: 10 sccm) por 5 min. Inspecione os padrões. NOTA: Para gravação da camada de Cr, o processo de RIE é preferível para molhar ataque químico que provoca a reacção desfavorável com a camada de Cu. </li><li> Remover o fotorresistente permaneceu sobre as camadas de metal por imersão a bolacha em acetona (10 ml), IPA (10 ml), e água desionizada (20 ml), respectivamente. Em seguida, seque-o com nitrogênio. </li><li> PI Spincoat (2 ml) no metal depositado da bolacha, por pipetagem, a 4000 rpm durante 1 minuto para formar uma camada de 1,2 mícrons de espessura, pré-cozer numa placa de aquecimento a 150 ° C durante 5 min, e pós-asse a 250 ° C durante 2 horas. </li><li> Spincoat um fotorresistente (2 ml) com três passos a 900 rpm durante 10 seg, 1.100 rpm, durante 60 s, e 4000 rpm durante 20 segundos e, em seguida, curar numa placa de aquecimento a 75 ° C durante 30 min. </li><li> Alinhe os padrões de PI para encapsular a eletrônica Cu (sensores, design fractal &#39;Peano&#39; com 35 mm de largura e interconexões; design de malha aberta com serpentina 250mm de largura) com os fractais e interconexões pré-definidos Cu usando um alinhador UV (de energia: 10 mW / seg) com tempo de exposição de 25 seg. </li><li> Desenvolver o photoresist com um desenvolvedor diluído (1: 2 proporção de desenvolvedor e água DI) por um minuto, lave com água DI, e seca com azoto. Inspecione os padrões usando um microscópio para confirmar a dimensão do traço e encontrar quaisquer defeitos de partículas. NOTA: Se houver quaisquer defeitos indesejáveis, em seguida, retire photoresist por lavagem com água acetona / IPA / DI. Após a secagem com azoto, repita os passos a partir de 1.2.10 a 1.2.13. </li><li> Etch a camada IP com RIE (pressão: 170 mTorr, potência: 150 W, O 2 gás: 20 sccm) durante 25 min. Inspecione os padrões. </li><li> Remover o fotorresistente manteve-se por imersão da bolacha em acetona (10 ml), IPA (10 ml), e água desionizada (20 ml), respectivamente. Em seguida, seque-o com nitrogênio. </li></ol></li><li> Prepara-se uma membrana elastomérica <ol><li> Prepara-se uma encapsulação 10 g de mistura de silicone (1:Proporção de 1 volume de base e agente de cura) e adicionar uma tinta preta 15 com uma relação de volume para um, que é o de facilitar as medições de controlo da variação da temperatura sobre a pele utilizando uma câmara de infravermelhos. NOTA: O silicone utilizado (borracha de encapsulamento claro) oferece características únicas de baixa viscosidade, claridade óptica, e isolamento elétrico / proteção para o dispositivo 16. </li><li> Spincoat 8 g da mistura numa placa de Petri a 150 rpm durante 1 minuto para formar um 500 mm de espessura de membrana elastomérica e cura à temperatura ambiente durante S / N. NOTA: O material tem de ser colocado sobre uma superfície plana para a espessura uniforme. </li><li> Cortar a membrana para o tamanho desejado de 70 mm x 30 mm, utilizando uma lâmina de barbear afiada suavemente e retirá-la da placa de Petri. </li></ol></li><li> Recuperar e transferir eletrônica <ol><li> Cortar uma fita solúvel em água (25 mm x 80 mm) e suavemente laminar para os padrões electrónicas fabricadas e colocá-los numa placa de aquecimento a 130 ° Cdurante 3 min. NOTA: elevação da temperatura a camada de PDMS expande na bolacha de Si para ajudar a dissociação dos padrões electrónicos a partir da superfície. </li><li> Retire a fita rapidamente do PDMS / Si wafer para recuperar os padrões eletrônicos. </li><li> Depositar uma espessura de 20 nm Cr (por aderência) seguido por um a 50 nm de espessura de dióxido de silício (SiO2) em padrões recuperados por evaporação por feixe de elétrons. </li><li> Tratar UV / ozono através da lâmpada de UV (365 nm, 8,9 mW / cm 2) sobre a membrana de silicone alvo durante 2 minutos para activar a superfície. </li><li> Transferir os padrões para a membrana de silicone, colocando os padrões obtidos na fita para o local desejado e uniformemente aumentando a pressão do lado de cima para baixo dos padrões no substrato. Aplicar água para dissolver a fita durante 5 min. NOTA: O processo descrito de transferência de materiais é facilitada através de ligação covalente (Si-O-Si) entre o dióxido de silício depositado e o substrato de silicone activado por UV 17 </sup&gt;. </li><li> Retire a fita, enxaguar com água desionizada, e seco numa placa de aquecimento a 90 ° C durante 1 min. </li></ol></li><li> Encapsular o dispositivo utilizando uma membrana de silicone <ol><li> Prepara-se uma encapsulação 10 g de mistura de silicone (1: 1 razão em volume de base e agente de cura). </li><li> Cubra as superfícies de contato do cabo com um pedaço PDMS rectangular (22 × 6 × 1 mm3) por van der Waals ligação com a membrana de silicone baixo para evitar silicone revestimento das almofadas. </li><li> Spincoat a 5 g de mistura de silicone a 4.000 rpm durante 1 minuto para formar uma camada de 5 mm de espessura sobre a electrónica e transferidos, em seguida, curar à temperatura ambiente durante S / N. </li></ol></li><li> Conecte um cabo de fita flexível para aquisição de dados <ol><li> Aplicar o fluxo de aço líquido (0,5 ml), por pipetagem, nas almofadas do conector durante 3 seg a tornar a superfície limpa. </li><li> Ligar um cabo de fita fino, flexível sobre os pontos de contacto com a pressão a alta temperatura (&gt; 60 ° C). A straightene cabelo típicor oferece fácil manuseio e colagem. NOTA: O micro-cabo película é preferível à solda-fio duro convencional para evitar qualquer fractura mecânica das membranas de metal transferidos sobre um silicone. </li><li> Verifique a conexão elétrica usando um multímetro digital. O valor da resistência é esperado inferior a 1 Ohm entre a almofada sensor com uma extremidade e a outra extremidade do cabo de película (distância de ~ 1 cm de distância). </li><li> Ligar a outra extremidade do cabo de fita para uma placa de circuito impresso personalizado com a mesma estratégia descrita no passo 1.6.2. </li><li> Verifique a conexão elétrica usando um multímetro digital. </li><li> Conecte o dispositivo com o hardware de aquisição de dados soldando fios convencionais no PCB. </li></ol></li></ol> 2. Testes clínicos <ol><li> Limpar o dispositivo utilizando uma solução desinfectante <ol><li> Preparar 205 g de uma solução desinfectante diluído (proporção de 40: 1 volume de água e solução). </li><li> Pulverizar osolução (10 g) no dispositivo e mergulhe-o por 10 min. NOTA: O líquido de limpeza desinfectante diluído pode ser armazenado à temperatura ambiente. </li><li> Enxágüe com água três vezes e seque-a com tecidos limpos. </li></ol></li><li> Configurar uma série de equipamentos para testes de dispositivo <ol><li> Preparar e ligar um amplificador lock-in com uma fonte de corrente, um multiplexer, e o software personalizado instalado em um computador portátil para gravação de dados. </li><li> Coloque uma câmera infravermelha em um tripé e se concentrar em um objeto de destino para a termografia como uma referência. </li><li> Configure os parâmetros do sistema de um amplificador lock-in para medir a condutividade térmica (freqüência: 1 e 3 Hz; constante de tempo: 3 e 1 seg; sensibilidade: 1 mV; reserva dinâmico: alta de reserva) e temperatura (freqüência: 997 Hz; tempo constante: 300 ms; sensibilidade: 2 mV; reserva dinâmico: baixo nível de ruído) com a corrente constante (2 mA aplicada). </li><li> Conectar dois dispositivos ferida, preparado por microfabricação e transferência de impressão e montado sobre ferida eSites contralateral, para o multiplexer direita antes de gravar dados de um paciente. </li></ol></li><li> Temperatura recorde e condutividade térmica NOTA: O software de aquisição de dados é feito por encomenda, que pode controlar remotamente o lock-in amplificador para monitoramento de dados em tempo real e poupança. Na medição de temperatura, cada ponto de dados é medida a cada 300 ms para 20 seg. O conjunto de dados para o primeiro 10 seg e 10 seg próxima são usados ​​para calcular o valor da temperatura média e desvio padrão, respectivamente. Os dados gravados são salvos como um arquivo de valores separados por vírgula, que é usado para traçar um gráfico para comparação com dados de termografia infravermelha. Na medição da condutividade térmica, os sinais são 3Ω lida directamente a partir do ecrã de hardware (amplificador), que é então utilizada para calcular a condutividade térmica analiticamente. <ol><li> Suavemente esfregue os locais de aplicação do dispositivo sobre a pele usando álcool anti-séptico toalhetes 10. </li><li> 2.3.2) laminado dois dispositivos sobre os locais da pele desejado pressionando suavemente o dispositivo à pele com os dedos para facilitar a ligação suave: um sobre o local da ferida cirúrgica e o outro na localização contralateral como referência. </li><li> Meça a tensão eléctrica (3Ω), relacionada com a condutividade térmica, do dispositivo, iniciando a aquisição de dados. </li><li> Avaliar os dados obtidos para verificar o contacto conformada do dispositivo para a pele; valor anormal (&lt;0,1 W / mK) mostra mau contacto do dispositivo. </li><li> Meça a resistência elétrica para determinar a distribuição da temperatura e gravar dados através do software personalizado. </li><li> Tome imagens ópticas e IV dos dois dispositivos na pele. </li><li> Comparar os valores de temperatura a partir das imagens IR com os dados gravados a partir do dispositivo ferida (2.3.5). Adicione os dois valores para separar colunas em uma planilha personalizada. </li></ol></li><li> Analisar os dados gravados <ol><li> Exportar os dados gravados para oMolde para calcular automaticamente a temperatura e a condutividade térmica a partir de uma matriz de sensores no dispositivo personalizado. </li><li> Determinar os dados (de temperatura e condutividade térmica de acordo com a localização do sensor na escala de tempo diferente para comparação) ao longo de um mês (quatro conjuntos de dados no dia 1, 3, 15, e 30). </li><li> Analisar os dados por comparação de uma série de temperatura e dados de condutividade térmica de acordo com o tempo; Valores com elevação súbita ou queda diga a mudança de fase de cicatrização de feridas e / ou anormalidade inesperado em sites de feridas. </li></ol></li></ol>

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The authors declare that they have no competing financial interests.

This article highlights the methods and protocols to fabricate a conformal, skin-like electronics system that enables conformal lamination near the wound tissues, which offers quantitative measurement of skin temperature and thermal conductivity mapping on the skin. 
The key features include the utilization of novel techniques of materials transfer printing and hard-soft materials integration to design and develop the flexible/stretchable, soft electronic device. The use of biocompatible, elec...

No estudo clínico e de investigação biomédica, monitorização de cicatrização da ferida tem-se centrado sobre um método invasivo, que se baseia na avaliação histológica de tecido de mudança morfológica em feridas 1,2. Recentemente, avanços rápidos em tecnologias eletrônicas permitirá o desenvolvimento de ferramentas de análise de imagem e de alta precisão que pode inspecionar visualmente o processo de cicatrização através de imagens digitais 3,4 ou microscopia confocal de varredura e espectroscopia de 4,5. No entanto, estas abordagens de imagem exigem custos elevados, instrumentos ópticos de complicados e operações, e mais importante, os pacientes necessitam ser imobilizada durante o teste. Portanto, existe uma necessidade de novos dispositivos e sistemas que são quantitativa, não invasivo, de fácil utilização, de baixo custo, e multifuncional para oferecer o tratamento de feridas mais precisa. Aqui, nós introduzir um sistema electrónico de pele-como que fornece preciso, mapeamento em tempo real de Condu temperatura e térmicasctivity e proporciona um nível preciso de aquecimento em locais ferida via conformada laminação do dispositivo de forma não invasiva. Este dispositivo apresenta uma classe de tecnologia, epidérmicas sistemas montados na pele eletrônicos que são projetados para corresponder às propriedades mecânicas e de material (espessura total, rigidez à flexão, módulos eficazes, e densidade de massa) da epiderme 6-9. O dispositivo foi projetado em um, à prova de água-biocompatível pele-friendly, e forma reutilizável que pode ser lavado e desinfetado para aplicações clínicas em pacientes 10. O dispositivo electrónico conformada montado perto dos tecidos da ferida capta a fase de inflamação (de um processo de cicatrização de feridas), causado pelo aumento do fluxo de sangue e reacções enzimáticas para a ferida 11,12, através de gravação quantitativa de temperatura 8 e condutividade térmica 13, correlacionada com a hidratação . Estudos experimentais e computacionais determinar um projeto ótimo mecânica para accommodComeram movimentos naturais e aplicado estirpes sem fractura mecânica e capturar a física subjacente do alongamento mecânico do sistema electrónico semelhante à da pele que laminados conformalmente na superfície da pele, que proporciona a aquisição dos sinais de alta fidelidade. Os protocolos descritos neste artigo apresentamos os métodos de microfabricação para sistemas eletrônicos de pele-like, testando preparação, incluindo a limpeza do dispositivo, a instalação do equipamento em um ambiente clínico, e aplicações clínicas para a monitorização quantitativa de temperatura e condutividade térmica em feridas cutâneas.

<table><tbody><tr><td>3&quot; Silicon wafer</td><td>University Wafer, USA</td><td></td><td>Use as carrier to fabricate the device</td></tr><tr><td>Acetone</td><td>Fisher Scientific, USA</td><td>A18-1</td><td>Use to clean a wafer and to remove photoresist</td></tr><tr><td>Isopropanol (IPA)</td><td>Fisher Scientific, USA</td><td>A459-1</td><td>Use to clean a wafer</td></tr><tr><td>AZ4620 photoresist</td><td>AZ Electrionic Materials, USA</td><td></td><td>Use to make patterns on metals and polymers</td></tr><tr><td>AZ400K developer</td><td>AZ Electrionic Materials, USA</td><td></td><td>Use to develop AZ4620 photoresist</td></tr><tr><td>Chromium etchant</td><td>Transene, USA</td><td>1020AC</td><td>Use to etch Cr layer of device</td></tr><tr><td>Copper etchant</td><td>Transene, USA</td><td>ASP-100</td><td>Use to etch Cu layer of device</td></tr><tr><td>Sylgard 184 Silicone Elastomer Kit (PDMS)</td><td>Dow Corning, USA</td><td>39100000</td><td>Use as a substrate for &#039;dry&#039; retrieval</td></tr><tr><td>PI2545 polyimide</td><td>HD MicroSystem, USA</td><td></td><td>Use to encapsulate metal layer</td></tr><tr><td>Solaris</td><td>Smooth-On, USA</td><td></td><td>Use as substrate and to encapsulate device</td></tr><tr><td>Petridish</td><td>Carolina, USA</td><td>741255</td><td>Use as mold to make substrate</td></tr><tr><td>Water-Soluble Wave Solder Tape 5414</td><td>3M, USA</td><td>AM000000217</td><td>Use to retrive device from PDMS layer</td></tr><tr><td>High Activity Liquid Stainless Steel Flux</td><td>Worthington, USA</td><td>331929</td><td>Use to remove oxidation layer on Cu</td></tr><tr><td>Flexible, micro-film cable</td><td>Elform, USA</td><td></td><td>Use to make the electrical connection between the electronic device and the data acquisition system</td></tr><tr><td>pH Neutral Cleaner</td><td>Australian Gold, USA</td><td></td><td>Use as disinfectant solution to clean device in clinical testing</td></tr><tr><td>Solder</td><td>Kester, USA</td><td>24-6337-9703</td><td>Use as material to solder hard wires</td></tr><tr><td>Ultraviolet lamp</td><td>Cole-Parmer, USA</td><td>97600-00</td><td>Use to activate PDMS layer as hydrophilic surface</td></tr><tr><td>Multiplexer</td><td>FixYourBoard, USA</td><td>U802</td><td>Use to acquire measurements from six sensing components&amp;nbsp;</td></tr><tr><td>DC/AC current source</td><td>Keithley, USA</td><td>6221</td><td>Use to supply current</td></tr><tr><td>SMD Digital Hot Air Rework Station</td><td>Aoyue, China</td><td>968A+</td><td>Use to solder hard wires, to electrically connect between the device and external instruments</td></tr><tr><td>Infrared camera</td><td>FLIR, USA</td><td>435-0001-01-00</td><td>Use to take infrared images in experiment</td></tr><tr><td>Digital multimeter</td><td>Fluke, USA</td><td>117</td><td>Use to check electrical connection</td></tr><tr><td>Lock-in amplifier</td><td>Stanford Research System, USA</td><td>SR830</td><td>Use to perform four-point-probe-measurement</td></tr><tr><td>Electron beam evaporator</td><td>9 scale Vacuum Products, USA</td><td></td><td>Use to deposit thin films (Cu and SiO&lt;sub&gt;2&lt;/sub&gt;)</td></tr></tbody></table>

fabrication and characterization of a conformal skin-like electronic system for quantitative, cutaneous wound management

Recent advances in the development of electronic technologies and biomedical devices offer opportunities for non-invasive, quantitative assessment of cutaneous wound healing on the skin. Existing methods, however, still rely on visual inspections through various microscopic tools and devices that normally include high-cost, sophisticated systems and require well trained personnel for operation and data analysis. Here, we describe methods and protocols to fabricate a conformal, skin-like electronics system that enables conformal lamination to the skin surface near the wound tissues, which provides recording of high fidelity electrical signals such as skin temperature and thermal conductivity. The methods of device fabrication provide details of step-by-step preparation of the microelectronic system that is completely enclosed with elastomeric silicone materials to offer electrical isolation. The experimental study presents multifunctional, biocompatible, waterproof, reusable, and flexible/stretchable characteristics of the device for clinical applications. Protocols of clinical testing provide an overview and sequential process of cleaning, testing setup, system operation, and data acquisition with the skin-like electronics, gently mounted on hypersensitive, cutaneous wound and contralateral tissues on patients.

A Figura 1 apresenta uma visão geral das características do conformada, sistema eletrônico de pele semelhante, projetado para quantitativa, gestão de feridas cutâneas em pacientes. O dispositivo eletrônico multifuncional consiste em estruturas de microescala fractal 3,14 e serpentina filamentar traça 9,17 em uma fina membrana elastomérica que oferece capacidade de estiramento mecânico excepcional e bendability. O dispositivo compatível que é totalmente fechado por camada...

Watch this Scientific Journal Video about Fabrication and Characterization of a Conformal Skin-like Electronic System for Quantitative, Cutaneous Wound Management at JoVE.com

Fabrication and Characterization of a Conformal Skin-like Electronic System for Quantitative, Cutaneous Wound Management

This article presents methods to fabricate and characterize a conformal, skin-like electronic system and protocols for the use in clinical applications, particularly on cutaneous wound management.

Fabricação e caracterização de um Sistema Eletrônico Conformal-pele como para a gestão quantitativa, Ferida Cutânea

Recent advances in the development of electronic technologies and biomedical devices offer opportunities for non-invasive, quantitative assessment of ...

fabrication-characterization-conformal-skin-like-electronic-system

Universidad de Cartagena UDEC

Research

JoVE Journal

Bioengineering

8.8K visualizações.  Virginia Commonwealth University. This article presents methods to fabricate and characterize a conformal, skin-like electronic system and protocols for the use in clinical applications, particularly on cutaneous wound management. 

Vídeo: Fabrication and Characterization of a Conformal Skin-like Electronic System for Quantitative, Cutaneous Wound Management

Hollow Microneedle-based Sensor for Multiplexed Transdermal Electrochemical Sensing

The development of a minimally invasive multiplexed monitoring system for rapid analysis of biologically-relevant molecules could offer individuals suffering from chronic medical conditions facile assessment of their immediate physiological state. Furthermore, it could serve as a research tool for analysis of complex, multifactorial medical conditions. In order for such a multianalyte sensor to be realized, it must be minimally invasive, sampling of interstitial fluid must occur without pain or harm to the user, and analysis must be rapid as well as selective.
Initially developed for pain-free drug delivery, microneedles have been used to deliver vaccines and pharmacologic agents (e.g., insulin) through the skin.1-2 Since these devices access the interstitial space, microneedles that are integrated with microelectrodes can be used as transdermal electrochemical sensors. Selective detection of glucose, glutamate, lactate, hydrogen peroxide, and ascorbic acid has been demonstrated using integrated microneedle-electrode devices with carbon fibers, modified carbon pastes, and platinum-coated polymer microneedles serving as transducing elements.3-7,8
This microneedle sensor technology has enabled a novel and sophisticated analytical approach for in situ and simultaneous detection of multiple analytes. Multiplexing offers the possibility of monitoring complex microenvironments, which are otherwise difficult to characterize in a rapid and minimally invasive manner. For example, this technology could be utilized for simultaneous monitoring of extracellular levels of, glucose, lactate and pH,9 which are important metabolic indicators of disease states7,10-14 (e.g., cancer proliferation) and exercise-induced acidosis.15

This article details the construction of a multiplexed microneedle-based sensor. The device is being developed for in situ sampling and electrochemical analysis of multiple analytes in a rapid and selective manner. We envision clinical medicine and biomedical research uses for these microneedle-based sensors.

Sensor de microagulhas baseado oco para Multiplexed Transdermal Eletroquímica Sensing

The development of a minimally invasive multiplexed monitoring system for rapid analysis of biologically-relevant molecules could offer individuals ...

Bioengenharia

Bridging the Bio-Electronic Interface with Biofabrication

Advancements in lab-on-a-chip technology promise to revolutionize both research and medicine through lower costs, better sensitivity, portability, and higher throughput. The incorporation of biological components onto biological microelectromechanical systems (bioMEMS) has shown great potential for achieving these goals. Microfabricated electronic chips allow for micrometer-scale features as well as an electrical connection for sensing and actuation. Functional biological components give the system the capacity for specific detection of analytes, enzymatic functions, and whole-cell capabilities. Standard microfabrication processes and bio-analytical techniques have been successfully utilized for decades in the computer and biological industries, respectively. Their combination and interfacing in a lab-on-a-chip environment, however, brings forth new challenges. There is a call for techniques that can build an interface between the electrode and biological component that is mild and is easy to fabricate and pattern.
Biofabrication, described here, is one such approach that has shown great promise for its easy-to-assemble incorporation of biological components with versatility in the on-chip functions that are enabled. Biofabrication uses biological materials and biological mechanisms (self-assembly, enzymatic assembly) for bottom-up hierarchical assembly. While our labs have demonstrated these concepts in many formats 1,2,3, here we demonstrate the assembly process based on electrodeposition followed by multiple applications of signal-based interactions. The assembly process consists of the electrodeposition of biocompatible stimuli-responsive polymer films on electrodes and their subsequent functionalization with biological components such as DNA, enzymes, or live cells 4,5. Electrodeposition takes advantage of the pH gradient created at the surface of a biased electrode from the electrolysis of water 6,7,. Chitosan and alginate are stimuli-responsive biological polymers that can be triggered to self-assemble into hydrogel films in response to imposed electrical signals 8. The thickness of these hydrogels is determined by the extent to which the pH gradient extends from the electrode. This can be modified using varying current densities and deposition times 6,7. This protocol will describe how chitosan films are deposited and functionalized by covalently attaching biological components to the abundant primary amine groups present on the film through either enzymatic or electrochemical methods 9,10. Alginate films and their entrapment of live cells will also be addressed 11. Finally, the utility of biofabrication is demonstrated through examples of signal-based interaction, including chemical-to-electrical, cell-to-cell, and also enzyme-to-cell signal transmission. 
Both the electrodeposition and functionalization can be performed under near-physiological conditions without the need for reagents and thus spare labile biological components from harsh conditions. Additionally, both chitosan and alginate have long been used for biologically-relevant purposes 12,13. Overall, biofabrication, a rapid technique that can be simply performed on a benchtop, can be used for creating micron scale patterns of functional biological components on electrodes and can be used for a variety of lab-on-a-chip applications.

This article describes a biofabrication approach: deposition of stimuli-responsive polysaccharides in the presence of biased electrodes to create biocompatible films which can be functionalized with cells or proteins. We demonstrate a bench-top strategy for the generation of the films as well as their basic uses for creating interactive biofunctionalized surfaces for lab-on-a-chip applications.

Colmatar a interface Bio-eletrônico com Biofabrication

Advancements in lab-on-a-chip technology promise to revolutionize both research and medicine through lower costs, better sensitivity, portability, and ...

A Full Skin Defect Model to Evaluate Vascularization of Biomaterials In Vivo

Insufficient vascularization is considered to be one of the main factors limiting the clinical success of tissue-engineered constructs. In order to evaluate new strategies that aim at improving vascularization, reliable methods are required to make the in-growth of new blood vessels into bio-artificial scaffolds visible and quantify the results. Over the past couple of years, our group has introduced a full skin defect model that enables the direct visualization of blood vessels by transillumination and provides the possibility of quantification through digital segmentation. In this model, one surgically creates full skin defects in the back of mice and replaces them with the material tested. Molecules or cells of interest can also be incorporated in such materials to study their potential effect. After an observation time of one&#8217;s own choice, materials are explanted for evaluation. Bilateral wounds provide the possibility of making internal comparisons that minimize artifacts among individuals as well as of decreasing the number of animals needed for the study. In comparison to other approaches, our method offers a simple, reliable and cost effective analysis. We have implemented this model as a routine tool to perform high-resolution screening when testing vascularization of different biomaterials and bio-activation approaches.

A Full Skin Defect Model to Evaluate Vascularization of Biomaterials In Vivo

Vascularization is key to approaches in successful tissue engineering. Therefore, reliable technologies are required to evaluate the development of vascular networks in tissue-constructs. Here we present a simple and cost-effective method to visualize and quantify vascularization in vivo.

A pele completa Defeito Modelo Estudar a vascularização de Biomateriais<em&gt; In Vivo</em

Insufficient vascularization is considered to be one of the main factors limiting the clinical success of tissue-engineered constructs. In order to ...

Generation of a Three-dimensional Full Thickness Skin Equivalent and Automated Wounding

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models reflect the human wound situation better than animal models. Although two-dimensional models are widely used to investigate processes such as cellular migration and proliferation, models that are more complex are required to gain a deeper knowledge about wound healing. Besides a suitable model system, the generation of precise and reproducible wounds is crucial to ensure comparable results between different test runs. In this study, the generation of a three-dimensional full thickness skin equivalent to study wound healing is shown. The dermal part of the models is comprised of human dermal fibroblast embedded in a rat-tail collagen type I hydrogel. Following the inoculation with human epidermal keratinocytes and consequent culture at the air-liquid interface, a multilayered epidermis is formed on top of the models. To study the wound healing process, we additionally developed an automated wounding device, which generates standardized wounds in a sterile atmosphere.

The goal of this protocol is to build up a three-dimensional full thickness skin equivalent, which resembles natural skin. With a specifically constructed automated wounding device, precise and reproducible wounds can be generated under maintenance of sterility.

Geração de espessura completa tridimensional Pele Equivalente e Automated Ferimento

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models ...

A Simple and Scalable Fabrication Method for Organic Electronic Devices on Textiles

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices cannot be worn under everyday conditions. Therefore, textiles are commonly considered the best substrate to accommodate electronic devices in wearable use. In this paper, we describe how to selectively pattern organic electroactive materials on textiles from a solution in an easy and scalable manner. This versatile deposition technique enables the fabrication of wearable organic electronic devices on clothes.

In this paper, we present a protocol to selectively deposit organic materials on textiles, which allows for the direct integration of organic electronic devices with wearables. The fabricated devices can be fully integrated in textiles, respecting their mechanical appearance and enabling sensing capabilities.

Um método de fabricação simples e escalável para dispositivos eletrônicos orgânicos sobre os têxteis

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices ...

Human Ex vivo Wound Model and Whole-Mount Staining Approach to Accurately Evaluate Skin Repair

Chronic non-healing wounds, which primarily affect the elderly and diabetic, are a significant area of clinical unmet need. Unfortunately, current chronic wound treatments are inadequate, while available pre-clinical models poorly predict the clinical efficacy of new therapies. Here we describe a high throughput, pre-clinical model to assess multiple aspects of the human skin repair response. Partial thickness wounds were created in human ex vivo skin and cultured across a healing time course. Skin wound biopsies were collected in fixative for the whole-mount staining procedure. Fixed samples were blocked and incubated in primary antibody, with detection achieved via fluorescently conjugated secondary antibody. Wounds were counterstained and imaged via confocal microscopy before calculating percentage wound closure (re-epithelialization) in each biopsy. Applying this protocol, we reveal that 2 mm excisional wounds created in healthy donor skin are fully re-epithelialized by day 4-5 post-wounding. On the contrary, closure rates of diabetic skin wounds are significantly reduced, accompanied by perturbed barrier reformation. Combining human skin wounding with a novel whole-mount staining approach allows a rapid and reproducible method to quantify ex vivo wound repair. Collectively, this protocol provides a valuable human platform to evaluate the effectiveness of potential wound therapies, transforming pre-clinical testing and validation.

Here we demonstrate an optimized technique for assessing wound repair using ex vivo human skin combined with a whole-mount staining approach. This methodology provides a pre-clinical platform for the evaluation of potential wound therapies.

Modelo de ferida ex vivo humana e abordagem de coloração de montagem inteira para avaliar com precisão o reparo da pele

Chronic non-healing wounds, which primarily affect the elderly and diabetic, are a significant area of clinical unmet need. Unfortunately, current chronic ...

Biologia do Desenvolvimento

Generation of Self-assembled Vascularized Human Skin Equivalents

Human skin equivalents (HSEs) are tissue engineered constructs that model epidermal and dermal components of human skin. These models have been used to study skin development, wound healing, and grafting techniques. Many HSEs continue to lack vasculature and are additionally analyzed through post-culture histological sectioning which limits volumetric assessment of the structure. Presented here is a straightforward protocol utilizing accessible materials to generate vascularized human skin equivalents (VHSE); further described are volumetric imaging and quantification techniques of these constructs. Briefly, VHSEs are constructed in 12 well culture inserts in which dermal and epidermal cells are seeded into rat tail collagen type I gel. The dermal compartment is made up of fibroblast and endothelial cells dispersed throughout collagen gel. The epidermal compartment is made up of keratinocytes (skin epithelial cells) that differentiate at the air-liquid interface. Importantly, these methods are customizable based on needs of the researcher, with results demonstrating VHSE generation with two different fibroblast cell types: human dermal fibroblasts (hDF) and human lung fibroblasts (IMR90s). VHSEs were developed, imaged through confocal microscopy, and volumetrically analyzed using computational software at 4- and 8-week timepoints. An optimized process to fix, stain, image, and clear VHSEs for volumetric examination is described. This comprehensive model, imaging, and analysis techniques are readily customizable to the specific research needs of individual labs with or without prior HSE experience.

The goal of this protocol is to describe the generation and volumetric analysis of vascularized human skin equivalents using accessible and simple techniques for long term culture. To the extent possible, the rationale for steps is described to allow researchers the ability to customize based on their research needs.

Geração de Equivalentes de Pele Humana Vascularizada Auto-montado

Human skin equivalents (HSEs) are tissue engineered constructs that model epidermal and dermal components of human skin. These models have been used to ...

Generation of a Simplified Three-Dimensional Skin-on-a-chip Model in a Micromachined Microfluidic Platform

This work presents a new, cost-effective, and reliable microfluidic platform with the potential to generate complex multilayered tissues. As a proof of concept, a simplified and undifferentiated human skin containing a dermal (stromal) and an epidermal (epithelial) compartment has been modelled. To accomplish this, a versatile and robust, vinyl-based device divided into two chambers has been developed, overcoming some of the drawbacks present in microfluidic devices based on polydimethylsiloxane (PDMS) for biomedical applications, such as the use of expensive and specialized equipment or the absorption of small, hydrophobic molecules and proteins. Moreover, a new method based on parallel flow was developed, enabling the in situ deposition of both the dermal and epidermal compartments. The skin construct consists of a fibrin matrix containing human primary fibroblasts and a monolayer of immortalized keratinocytes seeded on top, which is subsequently maintained under dynamic culture conditions. This new microfluidic platform opens the possibility to model human skin diseases and extrapolate the method to generate other complex tissues.

Here, we present a protocol to generate a three-dimensional simplified and undifferentiated skin model using a micromachined microfluidic platform. A parallel flow approach allows the in situ deposition of a dermal compartment for the seeding of epithelial cells on top, all controlled by syringe pumps.

Geração de um modelo simplificado de pele em um chip tridimensional em uma plataforma microfluida micromaquinda

This work presents a new, cost-effective, and reliable microfluidic platform with the potential to generate complex multilayered tissues. As a proof of ...

Conformable Wearable Electrodes: From Fabrication to Electrophysiological Assessment

Wearable electronic devices are becoming key players in monitoring the body signals predominantly altered during physical activity tracking. Considering the growing interest in telemedicine and personalized care driven by the rise of the Internet of Things era, wearable sensors have expanded their field of application into healthcare. To ensure the collection of clinically relevant data, these devices need to establish conformable interfaces with the human body to provide high-signal-quality recordings and long-term operation. To this end, this paper presents a method to easily fabricate conformable thin tattoo- and soft textile-based sensors for their application as wearable organic electronic devices in a broad spectrum of surface electrophysiological recordings. 
The sensors are developed through a cost-effective and scalable process of cutaneous electrode patterning using poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), the most popular conductive polymer in bioelectronics, on off-the-shelf, wearable substrates. This paper presents key steps in electrode characterization through impedance spectroscopy to investigate their performance in signal transduction when coupled with the skin. Comparative studies are required to position the performance of novel sensors with respect to the clinical gold standard. To validate the fabricated sensors' performance, this protocol shows how to perform various biosignal recordings from different configurations through a user-friendly and portable electronic setup in a laboratory environment. This methods paper will allow multiple experimental initiatives to advance the current state of the art in wearable sensors for human body health monitoring.

Two recent technologies-tattoo and textiles-have demonstrated promising results in cutaneous sensing. Here, we present the fabrication and evaluation methods of tattoo and textile electrodes for cutaneous electrophysiological sensing. These electronic interfaces made of conductive polymers outperform the existing standards in terms of comfort and sensitivity.

Eletrodos vestíveis conformáveis: da fabricação à avaliação eletrofisiológica

Wearable electronic devices are becoming key players in monitoring the body signals predominantly altered during physical activity tracking. Considering ...

Development of a Benchtop Model for Evaluating the Compatibility of Wound Dressing Materials with Negative Pressure Wound Therapy Systems

Negative pressure wound therapy (NPWT) systems facilitate wound healing by applying sub-atmospheric pressure to the wound bed, which promotes granulation tissue formation and reduces inflammation. Wound dressings can be used with these systems to enhance healing; however, the effects of dressings on NPWT device performance are challenging to assess. The purpose of this study was to develop a benchtop flesh analog model for testing the compatibility of wound dressing materials with NPWT devices. In this study, a chitosan-based advanced wound care device was evaluated for its effects on NPWT performance under maximum and minimum therapy pressures. The goal was to use the model to compare pressure readings and fluid collection for samples with and without the chitosan wound care device. The benchtop model was constructed using a plastic box connected to multiple pressure gauges. A circular defect was created on a piece of pork belly, used as the flesh analog, and inserted into the box. The defect was filled with standard NPWT foam or foam combined with the wound dressing. Simulated body fluid containing bovine serum was added to the box, which was then tested at either maximum (-200 mmHg) or minimum (-25 mmHg) pressures for 72 h. Pressure and fluid collection were recorded every 12 h. The NPWT system successfully maintained pressure over the 72 h test period, both with and without the test dressings. The addition of the wound dressings did not impact fluid collection. The test box proved effective as a benchtop model, as it could be sealed and maintained vacuum conditions over the 72 h testing period. This model successfully demonstrated its utility in evaluating the compatibility of wound dressing materials with NPWT systems.

This study presents a benchtop model designed to evaluate the compatibility of wound dressing materials with negative pressure wound therapy systems by assessing pressure and fluid collection over 72 h under continuous and intermittent pressure settings.

Desenvolvimento de um Modelo de Bancada para Avaliação da Compatibilidade de Materiais de Curativos com Sistemas de Terapia de Feridas por Pressão Negativa

Negative pressure wound therapy (NPWT) systems facilitate wound healing by applying sub-atmospheric pressure to the wound bed, which promotes granulation ...