The implementation and the performance analysis of the multi-channel software-based lock-in amplifier for the stiffness mapping with atomic force microscope (AFM)

Abstract

Abstract. In this paper the implementation of the surface stiffness mapping method with the dynamic measurement mode of atomic force microscopy (AFM) is presented. As the measurement of the higher harmonics of the cantilever's torsional bending signal is performed, we are able to visualize non-homogeneities of the surface stiffness. In order to provide signal processing with the desired sensitivity and selectivity, the lock-in amplifier-based solution is necessary. Due to the presence of several useful frequencies in the signal, the utilization of several simultaneously processing channels is required. Therefore the eight-channel software-based device was implemented. As the developed solution must be synchronized with the AFM controller during the scanning procedure, the real-time processing regime of the software is essential. We present the results of mapping the surface stiffness and the performance tests results for different working conditions of the developed setup.

The determination of the spring constant of T-shaped cantilevers using calibration structures

“…The experiments have been carried out using the measurement system with developed NanoSwing mode, allowing mapping to be performed of the Young modulus, adhesion (snap-off force), maximum force, tip-sample energy dissipation and other properties [16]. This setup was also used for mapping of the stiffness of the surface by acquisition of eight high harmonics of the torsional oscillation of the cantilever [33]. In this case, however, the outcome is qualitative.…”

Structural and morphological studies of manganese-based cathode materials for lithium ion batteries

“…Atomic Force Microscopy measurements were performed in ambient conditions using modified commercial setup Innova from Bruker (former Veeco) with enabled home-made NanoSwing mode [32][33][34]. This technique allows mapping of the mechanical properties of the surface, therefore it was used in order to image the topography, as well as the stiffness and the adhesion.…”

Development of the photostimulated Kelvin Probe Force Microscopy setup. The tool for nanoscale diagnostic of optoelectrical properties of the surface.

“…Due to the specific hardware and software features provided by the producer, this setup allows to perform the integration with auxiliary units in order to obtain desired functionality. Such advantage was used formerly in the implementation of several different experimental upgrades and modifications [11][12][13][14][15][16]. In case of described mode, following features were used: pixel synchronization with handshaking, auxiliary analogue signal acquisition and internal signals connections mapping edition.…”

“…As a main part of the auxiliary unit, PXI data acquisition and processing system from National Instruments programmed using LabView 2013 environment was utilized. In order to provide desired computational performance, in particular the response time to external signals, Real Time regime was enabled [12,15,16]. Additionally, home-made electronic units, including the LED's drivers providing linear current control as well as the kHz frequency switching were designed and assembled.…”