tailieunhanh - Recent Optical and Photonic Technologies Part 14

Tham khảo tài liệu 'recent optical and photonic technologies part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 374 Recent Optical and Photonic Technologies plastic solar cells Padinger et al. 2003 . OET devices fabricated with P3HT PCBM polymer films in place of amorphous silicon have similar functionality to standard OET devices Wang et al. 2009 . Another alternate photosensitive material is cadmium sulphide CdS which is another photoconductive semiconductor. The bandgap of CdS is larger than that of a-Si so OET made of CdS films are actuated using blue light Higuchi et al. 2008 . Functionality is also similar to the standard OET device although a chemical process can be used for the CdS deposition as opposed to PECVD for a-Si. The OET device can also be reconfigured physically. One form is the use of amorphous-silicon-coated surfaces for both the upper and lower electrodes Hwang et al. 2008b . This configuration is designed to reduce nonspecific particle adhesion when manipulation objects that experience negative OET forces such as polystyrene beads. In the standard OET device polystyrene beads can be levitated by the vertical component of the electric field gradient bringing them into contact with the upper ITO-coated electrode. More than 50 of these particles adhere to the ITO-coated electrode rendering them immovable by OET forces. By using a-Si for both electrodes the forces due to the vertical electric field gradients are cancelled out and the polystyrene beads remain at a metastable position that is approximately midway between the two electrode surfaces. In this version of the OET device nonspecific adhesion is reduced to less than 20 of the particles Hwang et al. 2008b . However optical microscopy through the a-Si coated electrodes may present some viewing issues for certain types of particles such as biological cells. Another type of OET device combines the two discrete electrode surfaces onto a single substrate. This version of OET uses an interdigitated array of amorphous silicon electrodes to enable optical control of an electric field using a single substrate