A dry release of polyimide electrodes using Kapton film and application to EEG signal measurements

Abstract

We describe here a simple and novel method to fabricate polyimide (PI) electrodes without a complex process to release completed PI electrodes from the substrates after full-curing process. We separated the PI electrodes from the Si-wafer prior to full-curing process, and these non full-cured electrodes were placed between the Kapton films, and we performed full-curing process with these sandwiched electrodes. Then, PI electrodes were easily and clearly released from the substrate without the sacrificial layers. We assessed the mechanical properties of fabricated electrodes comparing with non full-cured PI electrodes to investigate the full-curing effect between Kapton films. The electrical property was evaluated by measuring the impedance. Testing of the cyto-toxicity of full-cured electrodes using human mesenchymal stem cells (hMSCs) and mouse fibroblasts (L929) was carried out and the electrodes fabricated by proposed method were nontoxic and could be used as implantable electrodes. We also found that the electrodes, uniformly spread on the surface of mouse skulls while maintaining close contact, could successfully measure multichannel EEG signals.

Soldering-based easy packaging of thin polyimide multichannel electrodes for neuro-signal recording

“…The via-hole of the soft-baked first PI layer was fabricated by exposure to UV light (length: 365 nm, energy: 110 mJ cm −2 ) through a mask, followed by developing and rinsing processes. The first metal layer (Ti/Au = 30/100 nm thickness) was deposited using an e-beam evaporator, and the recording sites, interconnection pads and interconnection lines were patterned following reported wet metal etching processes [17]. Onto the metal patterns, the second PI layer was spin-coated, followed by soft-baking to passivate the metal line.…”

Balloon Catheter-Integrated Piezoelectric Micropyramid Arrays for Measuring Vascular Stiffness

“…p-NC was filled into the negative MPs and cured at 95 °C for 1 h to become a p-MP array (Figure a-i). The p-MP array was cut into a size of 1 × 3 mm 2 and sandwiched between the Au/Ti electrodes patterned on the PI substrate (thickness: Au, 100 nm; Ti, 20 nm; PI, 35 μm) to make the p-MP sensor (Figure a-ii,iii) . The p-MP sensor was then attached to a PTCA balloon catheter using Dymax.…”

Development and Experimental Validation of a Dry Non-Invasive Multi-Channel Mouse Scalp EEG Sensor through Visual Evoked Potential Recordings

“…Many research groups have proposed various mouse EEG electrodes positioned on diverse places to understand diverse signals according to brain activation. Such advanced methods like electrodes measuring intracranial EEG [ 2 , 12 , 13 , 14 , 15 ], surface field potential [ 16 ], epidural EEG [ 17 ], and epicranial EEG [ 3 , 18 , 19 , 20 , 21 , 22 ] have been proposed to be employed in mice. Many researchers conducted invasive EEG-related studies using laboratory animals with beneficial accessibility for surgical procedures regarding normal and disease models.…”