Colloidal Microspheres and AFM Cantilevers, Standard and Custom Colloidal AFM Probes

sQube® is the world leading manufacturer of colloidal probes for Atomic Force Microscopy (AFM)

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Colloidal probes are AFM probes with а spherical colloidal particle attached to the free end of the AFM cantilever by a suitable adhesive. They are commonly used for force measurements on different samples in air and liquids.

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Select microsphere material

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Using a sphere with a radius in the low micrometer range rather than a sharp AFM tip with an apex radius of curvature in the low nanometer range has important advantages in specific applications.

Unlike the complex apex shape of an etched silicon AFM tip, the simple, well-defined spherical shape of colloidal particles allows quantitative hardness calculations based on the sphere indenter model. In addition, the larger contact area makes force measurements and topography scans on delicate samples such as soft polymers and living matter safer, with lower risk of sample damage.

The different available sphere materials are beneficial for specific chemical, physical or biological property requirements. In contrast, the vast majority of sharp AFM tips are made of silicon, silicon nitride or quartz-like materials, while other materials are available only as coatings.

Colloidal probes are growing in popularity over the last two decades with increasing number of applications for studying mechanical properties, adhesion, particle-surface interactions, hydrodynamics, etc. sQube® is there to meet the present and future requirements of the scientific and industrial communities.

Examples of our products:

2 µm SiO2 microsphere

on NANOSENSORS™ SD-qp-CONT-TL tipless AFM cantilever

4.6 µm PMMA microsphere

on NanoWorld® PNP-TR-TL-Au tipless AFM cantilever

Colloidal AFM probes with spheres made of silicon dioxide, borosilicate glass, gold, polystyrene and acrylic (PMMA) are available in different dimensions ranging from 1.5 to 20 micrometers. Please note that colloidal AFM probes based on PNP AFM cantilevers are not suitable for application in fluids. For this application NanoAndMore recommends colloidal AFM probes based on qp-CONT or qp-SCONT AFM cantilevers.

Please note that state-of-the-art synthesis of gold microparticles does not guarantee ideal surface smoothness and ideal spherical shape. Some nanoroughness and small shape deviations are an inevitable result of the nature of the synthesis process.

Colloidal AFM probes with silicon dioxide microspheres

Silicon dioxide (SiO2) microspheres with diameters A = 2 µm, B = 3.5 µm, C = 6.62 µm, D = 10.2 µm or E = 15 µm, all ± 5%

Colloidal AFM probes with borosilicate glass microspheres

Borosilicate glass (BSG) microspheres with diameters 0 = 2.5 µm, A = 5 µm, B = 10 µm or C = 20 µm, all ± 10%

Colloidal AFM probes with gold microspheres

Gold (Au) microspheres* with diameters A = 1.5 – 3 µm, B = 3 - 5.5 µm or C = 5.5 - 9 µm

Colloidal AFM probes with polystyrene microspheres

Polystyrene (PS) spheres with diameters A = 1.98 µm, B = 3.6 µm, C = 6.1 µm, D = 10.8 µm or E = 14.45 µm, all ± 5%

Colloidal AFM probes with acrylic microspheres

Polymethyl methacrylate (PMMA, acrylic) microspheres with diameters A = 1.5 µm, B = 3.36 µm, C = 6.44 µm, D = 9.57 µm or E = 14.59 µm, all ± 5%

* Please note that the state-of-the-art synthesis process of gold microparticles cannot guarantee a perfectly spherical shape with perfect surface smoothness. Nanoroughness and small shape deviations are to be expected.

Colloidal probes with AFM cantilevers made of silicon, silicon nitride or a quartz-like material are available in different stiffnesses ranging from 0.01 N/m to 42 N/m.

Colloidal AFM probes with NANOSENSORS™ TL-NCH AFM cantilevers

The NANOSENSORS™ TL-NCH tipless AFM cantilevers are made of silicon and have rectangular shape. The nominal force constant is 42 N/m. They are highly doped to dissipate static charge and chemically inert to most common solvents.