Cell manipulation and operation have played important roles in modern biotechnology, hence a number of researchers have developed them during the past decades. In this paper we introduce two techniques based on dielectrophoresis (DEP) and optical tweezers: Distinction between viable cells and non-viable cells using DEP, Manipulating cells captured by positive DEP (pDEP) using optical tweezers. And then we suggest a system combined both DEP and optical tweezers, that would be a useful tool in biotechnology. This system will be useful to perform cell operation and other applications in biotechnology.