This is a tutorial for building a cheap and simple AFM head suitable for single molecule force spectroscopy. As the acquisition cost for commercially available AFMs is in the order of some hundred thousand dollars, this is an approach to make these instruments available to more research groups. Most of the structure can be made with rapid prototyping mehods, all that is left to do is to screw together the pieces. Nevertheless the user is supposed to have some experience with the matter as he doesn't get the support that comes with a commercial instrument. The performance of this instrument has been investigated in a paper published in:
Ferdinand Kühner, Robert A. Lugmaier, Steffen Mihatsch, and Hermann E. Gaub,
Print your atomic force microscope,
Rev. Sci. Instrum. 78, 075105 (2007).
printed parts(done by PTZ Prototypenzentrum with the SLS method)
main block (stl, sldprt) (1)
laser block (stl, sldprt) (2)
piezo block(12mm) (stl, sldprt) (3)
detector block (stl, sldprt) (4)
Owis stage: Owis MVT40C_z (5)
Naimotion stage: Naimotion MM3x (6)
laser: Schaefter + Kirchhoff 51FCM or 58FCM
detector diode: CentroVision QD50-0-SD (8)
piezo: Piezojena PA16/12 (9)
prism: Thorlabs PS910 (10)
fine screws & threads:
3x Thorlabs F3SS10
(small screws for laser block) (11)
3x Thorlabs F3SSN1 (12)
2x Thorlabs F25SS100
(more massive screws for main block) (13)
2x Thorlabs F25SSN1 (14)
drawer (stl, sldprt, eDrawings, jpg),
milled out of aluminium. It holds the fluid cell and is inserted in the recess at the bottom of the main block.
fluid cell (stl, sldprt, eDrawings, jpg),
milled from plexiglass. The cantilever is fixed on it by a piece of 0.2mm wire that is inserted in the small hole. Inserting the cantilever bends it to one side which holds the lever in place.
4x 0-80 for mounting the Naimotion stage (come with the NaiMotion Stage)
4x M3x20 for the piezo block
1x M3x10 for mounting the piezo
1x 5/16-24, about 15mm long, for mounting the detectorblock on the Naimotion stage
2x M2x5 for mounting the detector circuit board
1x M3x30 fixing screw for drawer
1x M3x20 positioning screw for drawer
3x M2x5 for fixing the laser in the laser block
2x M3x25 these hold the springs
4x M3 washer
2x springs (selfmade)
1x made2x5 (M2 screw with no head) for fixing the fluid cell in the drawer
1x M2.3x15 for mounting the owis stage to the main block
2x steel rod 2x10mm for stabilizing the OWIS stage
hex keys: 5/64", 1.5mm, (inch key about 1.25mm)
* Screw threads are cut by hand:
3x M2 in the laser block
* The small Thorlabs threads are pressed into the laser block from below (no need for glue in our case).
2x M2 in the detector block
4x M3 in the main block (2x for the springs, one for the drawer positioning screw. The one for the fixing screw is too deep to do with a cutter, so we used the screw itself.
4x 0-80 in main block for the NaiMotion Stage, these can also be done directly with the screws.
* The big Thorlabs threads are pressed into the main block from below (no need for glue in our case).
* The springs are handmade from steel wire. They roughly need to be strong enough so the laser block has a stable rest,
weak enough so it moves when you lightly press the corner which has no screw.
* The prism is glued into the laser block (not sure how much precision/calibration is needeed).
* Everything is screwed together. For details see the list of screws and this picture:
* The exact size of all the holes may depend on the method of printing, so using other methods it might happen that some holes for smaller screws have to be redrilled by hand or get too big to hold the screws. But our overall experience is that screw holes are printed rather too small than too big.
* We suppose you have some sort of controller for the AFM head and know how it needs to be connected to the piezo and the detector.