Impedance characterization, degradation, and in vitro biocompatibility for platinum electrodes on BioMEMS

Abstract

Fine control of molecular transport through microfluidic systems can be obtained by modulation of an applied electrical field across channels with the use of electrodes. In BioMEMS designed for biological fluids and in vivo applications, electrodes must be biocompatible, biorobust and stable. In this work, the analysis and characterization of platinum (Pt) electrodes integrated on silicon substrates for biomedical applications are presented. Electrodes were incorporated on the surface of silicon chips by adhesion of laminated Pt foils or deposited at 30°, 45° or 90° angle by e-beam or physical vapor (sputtering) methods. Electrical and physical properties of the electrodes were quantified and evaluated using electrical impedance spectroscopy and modelling of the electrode-electrolyte interfaces. Electrode degradation in saline solution at pH 7.4 was tested at room temperature and under accelerated conditions (90 °C), both in the presence and absence of an applied electrical potential. Degradation was quantified using atomic force microscopy (AFM) and inductively coupled plasma mass spectroscopy (ICP-MS). Biocompatibility was assessed by MTT proliferation assay with human dermal fibroblasts. Results demonstrated that the deposited electrodes were biocompatible with negligible material degradation and exhibited electrochemical behavior similar to Pt foils, especially for e-beam deposited electrodes. Finally, Pt electrodes e-beam deposited on silicon nanofabricated nanochannel membranes were evaluated for controlled drug delivery applications. By tuning a low applied electrical potential (<1.5 VDC) to the electrodes, temporal modulation of the dendritic fullerene 1 (DF-1) release from a source reservoir was successfully achieved as a proof of concept, highlighting the potential of deposited electrodes in biomedical applications.

Leveraging electrokinetics for the active control of dendritic fullerene-1 release across a nanochannel membrane

“…This higher porosity allowed for greater water penetration into the electrode stack and Ti or Ta adhesion layers, which unlike Pt, were not as chemically immune to high salinity solutions. These results were comparable to those described by Geninatti, et al 45 In future investigations, we intend to examine the degradation of the electrodes with an insulating layer, which previous studies 46, 47 have suggested may enhance both bioinertness and ICP. Results from these experiments demonstrated that Pt electrodes deposited on SiN with a SiO 2 layer had superior resistance to degradation, and were therefore employed in this configuration for the DF-1 release modulation study.…”

Direct electrical stimulation enhances osteogenesis by inducing Bmp2 and Spp1 expressions from macrophages and preosteoblasts

“…However, the optical images at different areas of the stimulated cells have shown that the apparent cell density at the vicinity of the electrodes is noticeably lower than those in the middle of the well. Besides, platinum electrodes have already been tested for its biocompatibility (Geninatti et al, ). Therefore, we believe that the excessive current density around the electrodes during stimulation has significant effects on cell viability and proliferation in our ES system (Balint, Cassidy, Hidalgo‐Bastida et al, ).…”

Proliferation and Cluster Analysis of Neurons and Glial Cell Organization on Nanocolumnar TiN Substrates

“…These materials are, for example, based on metals [ 13 ], carbon [ 14 , 15 ], or silicone compounds [ 16 ]. Commonly used electrode materials for the electrochemical analysis of biological samples, such as cells and tissues, are noble metals, like gold and platinum, because of their high conductivity, chemical stability, and biocompatibility [ 17 , 18 , 19 , 20 , 21 ].…”