Enormous efforts have been made towards the next generation of flexible, low-cost, environmental friendly printed electronics. Printed electronics are being explored for the manufacture of large-scale and flexible electronic devices by the patterned application of printable materials. They involve a large number of frontier scientific problems, including many generic technologies in materials, devices, manufacturing process and applications. First of all, preparation of environmental friendly and low-cost conductive ink plays a key role in the development of printed electronics. Combining with the recent progress of printed electronics, this review focuses on the synthesis of metal nanoparticles, preparation of metal nanoparticles-based conductive inks and their applications. The classifications, stabilization of printable metal nanoparticles, preparation method of conductive inks and sintering process, and their progresses in sensors, thin-film transistors, solar cells, and RFID are also briefly reviewed.

Contents
1 Introduction
2 Preparation of printable metal nanoparticles
2.1 Classification of metal nanoparticles
2.2 Synthesis of metal nanoparticles
2.3 Stabilization of metal nanoparticles
3 Preparation of metal nanoparticles-based conductive inks
4 Post-printing treatment and resistivity
4.1 Electrical resistivity
4.2 Sintering of printed conductive patterns
5 Applications
5.1 Transparent electrodes
5.2 Light emitting devices
5.3 Thin film transistors
5.4 Solar cells
5.5 Sensors
5.6 RFID tags
6 Conclusions