[JJBeansz]

Hi! This is my first time posting here, sorry for any mistakes. If I chose the wrong Forum please move my post where it would belong

I'm a electrical engineering student writing my bachelor thesis about microelectrodes to be implanted in the brain. Long story short I´m doing an analysis on a microelectrode that's been recently removed from a rats brain. The microelectrode didn't work so I'm searching for a reason why. My Professor told me about dendritic growth but I'm not sure that is what has happened because it looks like to gold thin film separated because of delaminations? To be very honest I have no idea what happened there. I'm currently reading about annealing because the microelectrodes where made sterile before the implantation.

I didn't make the microelectrodes myself, but I know how they were made. The first polyimide layer was spin coated on a silicon Wafer, afterwards the Gold layer was deposited using a DC Sputtering process and then structured. The Wafer area was then treated with oxygen plasma to achieve a better adhesion between both polyimide layers. Then the second Polyimide layer was also spin coated

My Professor always talks about how the problem that we have is that the adhesion between both polyimide layers is not strong and therefore delaminates. We are also searching for a way to make both Polyimide layers stick together but I´m out of ideas.

I can give more information about the processes made before the implantation and after the explantation if someone needs it! I've attached three pictures, one made with a microscope and two made with electron microscope.

I'm thankful for any help or indication on the direction that I should research

[chenbeier]

Can you get a cut (micro section or focus ion beam) of one of the dendritic to see is at whole gold or is there a core of polyimide or something else in it. Probably a EDX would help. I don't think it has something to do with implantation or explantation, more with manufacturing.