Hi Maria Bikuña , i did the same for a rubber substrate and got nice nanofiber matrix over my rubber surface. It was pretty simple. I think the important point is that the surface area of the insulating substrate (e.g. glass in your case) should be less than the Al foil. Secondly, you can use a rectangular shaped current collector (rather than a roller, if you can compromise on the rotating collector). That can make your experiment a little easier in the case of nonflexible surface.

Last but not the least, you can optimize the applied voltage and other parameters until you r satisfied.

Thirdly, i wonder what do you mean by repulsive forces ??

Thank you Syed Waqar Hasan . I will try to use a bigger Al foil beneath the glass.

I mean that the first polymer fibers lie on the glass. However, the following ones start to deposit in other areas out of the glass or start climbing up towards the needle as they polimerized. I don´t know if that is a common event.

Maria Bikuña , yes the electric field between the spinneret (the pin) and the collector (Al foil) is disturbed when you place an insulating material (glass) in between. That disturbance causes the nanofibers to deflect from the glass substrate and stick to those areas where they can find the electric field.

In addition of increasing the Al foil area, another attempt can be that you place the glass in between the spinneret and Al foil. Lets say if the distance between the spinneret and the collector is 10 cm, try to fix (hold) the sample at ~5 cm from the spinneret (i.e. within the electric field). This way, you can ensure a stable electric field between the collector and the spinneret while receiving the nanofibers at glass in between (before they reach the collector).

Best Wishes,