LEGO2NANO atomic force microscope

AFMs, in contrast to optical and electron microscopes, do not require expensive focusing lens components. Rather, they rely on sensing the direct action between a probe and a sample surface. The principle of the AFM is closely analogous to that of a vinyl record player. The AFM can work in three modes: contact mode, non-contact mode and tapping mode.

The low-cost LEGO AFM is designed to work in the contact mode, and the tip will be in contact with the sample during the scanning process. The LEGO AFM contains a sample stage that moves in x and y direction, a cantilever holder that moves in z direction, a laser and a photo detector to readout the deformation of the cantilever and a control system based on Arduino.

The structure of the LEGO AFM. In this hybrid stricter of LEGO AFM, the main structure is made of metal to guarantee a good stability, while the holders are assembled by LEGO part as well as 3D printed part to offer some versatility.

The Arduino based control system is to give the controlling signal for scanning voltage and take in the signal from the photo detector for analysis.

The probes used for the LEGO AFM. The probes are cantilever made of silicon nitride and with a sharp tip at the flexible end give a high resolution. The cantilevers are coated with gold to reflection the laser spot for readout.

The holder of the AFM probe, made of LEGO parts, and can be flexible in height and length.

Laser spot is reflected by the cantilever to readout the deformation caused by the roughness of the sample surface.

The laser holders, made by 3D printing. The outer part is to fix on the main structure and the inner part is adjustable in 2 dimensions.

Four-quadrant photo detector is to detect the position of the reflected laser spot.

The detector holders, also made by 3D printing. The outer part is to fix on the main structure and the inner part is adjustable in 2 dimensions.

Micrometer screws are used to adjust the position of the stage and the cantilever holder precisely.

The microscope is used to observe the position of the cantilever and the sample, as well as to calibrate the laser spot on the cantilever.

The piezoelectric actuators will extend or shrink with applied voltage to give a displacement in nanometer scale. The scanning voltage is tuned by the Arduino controller.