Why doesn't computer science follow biology more closely in computer design? Nature has proved with the brain that it can create complex computers with very little energy consumed and released, extremely low energy compared to a common computer.

However, I noticed the design is completely different, why hasn't anyone tried to or succeeded to create a similar one?

For example:

1) Computers use memory as the main building block. After that, a processor is used to manipulate it.

2) However, biological computers do not use memory as the main building block. This is a by-product. The main building block appears to be a combination of static geometry and design of the computer (DNA) which is combined with the energy generators (mitochondria, components of both DNA and energy transfer).
This might be more suitable as a comment than an answer. 

From computability point of view, any machine which uses finite memory (but not necessarily constant) at any point in time and modifies it according in a local way is equivalent to Turing machines (this is an informal statement of a result by Robin Gandy from 1980 IIRC). On the other hand Turing Machine models are simpler to deal with in many respects and therefore are easier as a object of study. Natural models of computation are usually more complicated to study.

There are also studies into natural models of computation. You may want to take a look at Aaron's answer here.