Wire, Mesh, and Fiber Electrodes for Paper-Based Electroanalytical Devices

Abstract

Here, we report the use of microwire and mesh working electrodes in paper analytical devices fabricated by origami paper folding (oPADs). The important new result is that Au wires and carbon fibers having diameters ranging from micrometers to tens of micrometers can be incorporated into oPADs and that their electrochemical characteristics are consistent with the results of finite element simulations. These electrodes are fully compatible with both hollow channels and paper channels filled with cellulose fibers, and they are easier to incorporate than typical screen-printed carbon electrodes. The results also demonstrate that the Au electrodes can be cleaned prior to device fabrication using aggressive treatments and that they can be easily surface modified using standard thiol-based chemistry.

Electroanalytical devices with pins and thread

“…42,43 Fosdick et al have reported the use of gold and carbon microwires as electrodes, and showed that they can be integrated with microfluidic paper-based analytical devices. 7 Stainless steel has been used as a material for auxiliary and quasireference electrodes in electroanalytical flow systems and other electrochemical applications. 39 Fernández-Abedul et al reported a flow system in which a hollow stainless-steel cylinder acted as both the outlet of the flow and the auxillary electrode.…”

Electrochemical detection in paper-based analytical devices using microwire electrodes

“…Recently, Crooks and coworkers fabricated ePADs with cylindrical microwire electrodes [24] using a similar concept to that reported by Garcia et al for polydimethylsiloxane (PDMS) microfluidic devices [25]. Microwires have many advantageous characteristics including high conductivity, ease of modification, and availability in many different pure and alloyed compositions.…”

“…They can also be cleaned and modified prior to incorporation using chemicals and solutions that cannot be used with ink, paste, or sputter-coated electrodes without contaminating or destroying the ePADs. The ePAD fabricated by Crooks et al, for example, used piranha solution (mixture of hydrogen peroxide and sulfuric acid) and subsequently modified electrodes with a self-assembled monolayer (SAM) prior to incorporation into the device [24]. Another advantage of incorporating an electrode with a micron-scale dimension is enhanced mass transport due to radial diffusion, leading to increased current density that should provide improved sensitivities and detection limits [26,27].…”

Desenvolvimento de sensores eletroquímicos e colorimétricos para aplicações em amostras de interesse forense

“…Para uso de eletrodos carbonáceos, além do uso de tinta condutiva, há trabalhos que fazem o uso do grafite [44,45] e da pintura direta no papel com minas de grafite [46][47][48]. Uma abordagem alternativa é o uso de fios metálicos fixados sobre a superfície do substrato de papel [49,50].…”

“…No campo que concerne o desenvolvimento de sensores eletroquímicos descartáveis e portáteis, há diversas pesquisas realizadas na literatura para a fabricação de eletrodos do tipo impressos através de diferentes tecnologias, mas basicamente utilizando tintas condutivas de carbono e outros metais [125][126][127], utilizando fios metálicos [49,128], construção de dispositivos em circuitos eletrônicos [78,129], confecção a partir de CDs (CDtrodos) [130][131][132], utilização direta de grafites [45,101] ou ainda "pintando/desenhando" com grafite sobre um substrato, comumente papel [47,48], entre outras formas.…”