Electrospinning involves the ejection of a charged polymer fluid onto which type of surface?

Electrospinning is a process used to create nanofibers from a polymer solution or melt by applying a high voltage to the fluid, which leads to the ejection of a charged polymer jet. The key to this process is the interaction between the charged polymer fluid and the surface it is being ejected toward.

When the charged polymer stream is directed towards an oppositely charged surface, it allows the fibers to be drawn and collected effectively due to the electrostatic attraction between the charges. This attraction helps ensure that the fibers are deposited more uniformly and can achieve the desired structural characteristics. The oppositely charged surface facilitates the formation of a stable fiber network, making it integral to the electrospinning process.

Utilizing an oppositely charged surface enhances the collection efficiency and quality of the spun fibers, vital for various applications in tissue engineering and material science. Hence, the answer is correct as electrospinning is most effective when targeting an oppositely charged surface to create a suitable environment for fiber formation.