Stretchable Dielectric Material for Conformable Bioelectronic Devices
- PDF / 695,947 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 112 Downloads / 218 Views
0926-CC02-02
Stretchable Dielectric Material for Conformable Bioelectronic Devices Candice Tsay1, Stephanie P. Lacour2, Sigurd Wagner1, Zhe Yu3, and Barclay Morrison III3 1 Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544 2 Department of Materials Science, University of Cambridge, Cambridge, CB2 3QZ, United Kingdom 3 Department of Biomedical Engineering, Columbia University, New York, NY, 10027
ABSTRACT We use a photo-patternable silicone polymer to fabricate an elastically deformable encapsulation film on stretchable gold lines that electrically conduct while stretched to >50% strain. To detect bioelectrical signals, these stretchable gold lines are patterned as leads and micro-electrodes. They need to be encapsulated with a material that is electrically insulating, as stretchable as the elastomeric substrate, and that can be readily patterned to define recording sites. First, we evaluate the biocompatibility of the elastic encapsulation polymer by assessing the viability of the organotypic hippocampal slices cultured on it. Then, to test the electrical performance of the encapsulation film under large mechanical stress, we measure the dielectric strength of the encapsulation film to 50% tensile strain. Our findings indicate that the photopatternable silicone material is a suitable interface to in vitro living tissue, and is a reliable stretchable insulator for soft and conformable electronic devices. INTRODUCTION The successful integration of electrical devices into biological environments requires both biochemical and mechanical compatibility at the electro-biological interface. At stake is the ability of the sensing/stimulating device to function and co-exist with the biological specimen without harming it or being damaged itself. A substrate material like polydimethylsiloxane (PDMS), which is compliant (Young’s modulus E ~ 1-3MPa), and elastically deformable, is a promising match for soft tissues like brain (E ~ 10kPa) [1]. We have developed a stretchable micro-electrode array (SMEA), a technology based on patterning conducting films on soft, elastomeric substrates, that maximizes conformability and bio-mechanical compatibility between array and soft biological tissues. Our first SMEA prototypes are designed for in vitro traumatic brain injury study [2, 3]. This novel technology is enabled by our discovery that thin gold films patterned on PDMS membranes remain electrically conductive after uni-axial stretch cycles to > 20% strain [4], and equi-biaxial stretching to 14% strain [5]. The arrays are encapsulated with a photo-patternable silicone film, which electrically insulates parts of the device from electrolytic environments, and also serves as a non-toxic interface to the organism and a barrier to corrosion. More importantly, the encapsulation film retains these properties under mechanical deformation, such as twisting, bending, and stretching. In this paper, we first describe the stretchability of the encapsulated stretchable electrodes and how to fabricate the SMEA, then d
Data Loading...
