| AVS 66th International Symposium & Exhibition | |
| MEMS and NEMS Group | Tuesday Sessions |
| Session MN-TuM |
| Session: | MEMS, BioMEMS, and MEMS for Energy: Processes, Materials, and Devices II |
| Presenter: | Christian Zorman, Case Western Reserve University |
| Authors: | Y. Sui, Case Western Reserve University A. Hess-Dunning, Louis Stokes Cleveland VA Medical Center R.M. Sankaran, Case Western Reserve University C.A. Zorman, Case Western Reserve University |
| Correspondent: | Click to Email |
The rapid advancement of flexible and stretchable electronics has stimulated the development of printing approaches as a means to fabricate metallic interconnects, antenna and other essential conducting structures. Unfortunately, metal inks have been limited to silver, copper, and gold, due to the complexity of nanoparticle synthesis and metallo-organic compound design. While sufficient for interconnects, the development of printed sensors is significantly limited by the small selection of printable metals. Recently, we reported a new class of inks that are based on inorganic metal salts that are converted to metallic structures by exposure to a low-temperature inert gas plasma. This approach to ink design opens up a much wider range of printable metals than currently available from conventional inks. We found that chemical, biological and mechanical sensors fabricated using this printing approach significantly outperformed the same sensors fabricated using conventional approaches, presumably due to the surface morphology of the printed sensors.
In this paper, we describe a method of controlling the surface morphology for metal structures fabricated using plasma activation of inorganic metal salt-based inks. We have found that the ink solvent plays a key role in the nucleation and crystal growth of metal nanostructures during the plasma reduction process. Using solvents of different vapor pressures, we were able to control the duration of plasma-induced liquid-phase nucleation and crystallization, thereby tuning the surface morphology, conversion depth, and resistivity of the printed metal structures. Silver nitrate-based ink was used for this study and the ink solvents in order of decreasing vapor pressure were ethylene glycol (EG), di-ethylene glycol (di-EG), and tri-ethylene glycol (tri-EG). The structural, morphological, and electrical properties of metals printed with different ink solvents were characterized by cross-sectional scanning electron microscopy (SEM), optical profilometry, and sheet resistance measurements, respectively. To show that the tunable morphology can be used to enhance the sensitivity of printed sensors, we fabricated and tested a silver-based hydrogen peroxide sensor using inks made from the three solvents.