Is your target substrate properly connected to the ground?

Yes it is. I am using Al foil as collector properly grounded. 

There might be two reasons in your case:

1- Al foil is very thin film. It may vibrate due to the strong electric field between the nozzle and target substrate. 

2- The surface of your Al foil might be hydrophobic so that your solution can not completely wet the surface of foil.

If you don't mind about getting aligned fibers, you can use a rotating drum collector. It usually helps to avoid this kind of mess when some polymers are electrospun.

Try to increase the distance between needle and collector.

Before that you supposed to check your condition making the 'Talyor cone'.

I found this on the internet, the same thing what i am trying to solve.

Watch from 5:20 to 5:40 in below link. 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182658/

That is what I was expecting. Even though your condition is making 'Taylor cone' at the end of the needle, increase the distance between the needle and collector. If you could not solve the problem by following my suggestion, make another solution which is higher concentration polymer solution.

Wish you good luck!!

It seems like you are using very high voltage and an unnecessary shorter distance between the nozzle and the collector. Make sure the fibers get grounded upon collection, which they seemingly aren't. They are talking to the field b/w the nozzle and the collector.

In my experience this is most likely caused by either the voltage being set too high or too low a surface tension. I would firstly try to decrease the voltage but if that doesn't work maybe try increasing the surface tension of the solution.

Hi, Saqib Siddiqui Have you finally figured out how to solve this problem? I need your information because unfortunately, I am facing the same problem with you but with different polymers. Thank you so much for your help.