While not widely implemented, there are several factors which motivate extending piezoresponse force microscopy (PFM) implementation to liquid environments. For example, liquid PFM may allow piezoelectric biomaterials to be investigated in physiological environments, thereby providing a characterization approach to understand the possible biofunctional relevance of piezoelectricity in a wide range of biomaterials, in principle down to the single molecule level. Moreover, given the potential use of ferroelectrics and other functional oxides in microfluidics and energy storage applications, which exploit the presence of polarization charge and screening mechanisms, it would be useful to be able to locally probe domain-dependent electromechanics, electromechanics, and surface potentials at the solid-liquid interface.
Imaging in liquid also provides a potential route for simultaneously minimizing capillary forces present in ambient air conditions, as well as the influence of long-range electrostatic forces on PFM data, localizing the electromechanical detection to the tip-sample contact. On the other hand, stray fields, solution conductivity, and damped cantilever oscillations may impede the application of PFM in liquid.
In this tutorial, the implementation of liquid PFM will be discussed. Reported results on domain imaging and switching of ferroelectric1-4 and organic5-8 materials will be presented. As well as the development and use of shielded probes.9,10 Importantly, the challenges in performing measurements and in interpreting the data, as well as possible future directions will be explored.
References 1 B. J. Rodriguez, S. Jesse, A. P. Baddorf, and S. V. Kalinin, Phys. Rev. Lett. 96, 237602 (2006). 2 B. J. Rodriguez, S. Jesse, A. P. Baddorf, S.-H. Kim, and S. V. Kalinin, Phys. Rev. Lett. 98, 247603 (2007). 3 N. Balke, S. Jesse, Y.-H. Chu, and S. V. Kalinin, ACS Nano 6, 5559-5565 (2012). 4 N. Balke, A. Tselev, T. M. Arruda, S. Jesse, Y.-H. Chu, and S. V. Kalinin, ACS Nano 6, 10139-10146 (2012). 5 S. V. Kalinin, B. J. Rodriguez, S. Jesse, K. Seal, R. Proksch, S. Hohlbauch, I. Revenko, G. L. Thompson, and A. A. Vertegel, Nanotechnology 18, 424020 (2007). 6 M. P. Nikiforov, G. L. Thompson, V. V. Reukov, S. Jesse, S. Guo, B. J. Rodriguez, K. Seal, A. A. Vertegel, and S. V. Kalinin, ACS Nano 4, 689-698 (2010). 7 G. L. Thompson, V. V. Reukov, M. P. Nikiforov, S. Jesse, S. V. Kalinin, and A. A. Vertegel, Nanotechnology 23, 245705 (2012). 8 M. P. Nikiforov, V. V. Reukov, G. L. Thompson, A. A. Vertegel, S. Guo, S. V. Kalinin, and S. Jesse, Nanotechnology 20, 405708 (2009). 9 B. J. Rodriguez, S. Jesse, K. Seal, A. P. Baddorf, S. V. Kalinin, and P. D. Rack, Appl. Phys. Lett. 91, 093130 (2007). 10 J. H. Noh, M. Nikiforov, S. V. Kalinin, A. A. Vertegel, and P. D. Rack, Nanotechnology 21, 365302 (2010).