Frequently Asked Questions

 about

 APPNANO Silicon Nitride Probes:

 Probe Series: HYDRA  ( silicon nitride probes with silicon tips)

 What are the advantages of new HYDRA probes supplied by APPNANO?

 APPNANO silicon nitride probes use the best features of silicon and silicon nitride properties. The tips are made out of silicon to get flexible sharpness. It means the tips could be made as sharp as standard silicon probes or as dull as conventional silicon nitride probes. This makes them adoptable to your application.  The cantilever is made out of silicon nitride for a better spring constant control.  The advantages are:

            (i)                  Customized tip sharpness.

(ii)                Silicon pad at the end of cantilever for laser reflection without reflex coating.

(iii)               Tip could be hydrophobic or hydrophilic for easy functionalization.

(iv)              Available in V-shape and Rectangular shape.

(v)                Handle Chip (substrate) made out of silicon with alignment grooves.

(vi)              Ease of establishing electrical contact using backside metal coating.

(vii)             One cantilever per chip to image soft and delicate samples without disturbance.

Can I use the HYDRA probes for tapping mode in fluid / air?

 Yes, HYDRA probes come in various lengths in the range of 50um to 200um. Usually short lengths 50um and 100um long cantilevers are ideal for tapping mode in fluid and air.

Can I use the HYDRA probe for contact mode in fluid / air?

Yes, usually 200um long cantilevers are preferred for contact mode applications. 

Can I use these probes without metal coating?

 Yes, some AFM systems do not require metal coating on the reflex side. The silicon pad at the end of the cantilever is designed to reflect laser without coating. Size of the pad is bigger than the laser spot size in most AFMs.

What are the advantages of using probes without reflex coating?

 When two materials with large difference in Coefficients of Thermal Expansion (CTE) are stacked together, an internal stress at the interface is generated. The stress in turn, causes bending of the structure. The effect is known as Bimorph Effect.  Silicon nitride is a low CTE material and gold is a very high CTE material. The bimorph effect causes bending of the Silicon nitride cantilevers coated with gold when used for imaging in fluid. The bending is in the order of a nanometer. This is also known as thermal drift. If the sample feature are comparable to the bimorph bending, it is becomes difficult to isolate the two.  Therefore to get a true image of samples with nanometer scale features in fluid one need to use probes without reflex coating.

HYDRA probes with silicon pads are ideal for such applications where bimorph effect is of concern.   This is a UNIQUE FEATURE of  HYDRA probes.

I want to image soft samples without damaging the sample with sharp tips, does APPNANO supply probes with large tip radius of curvature as in conventional nitride probes?

 Yes, HYDRA probes with large tip radius of curvature are available upon request.

I am not sure what probes would work for my application, how do I select?

 If you are new AFM user, our technical experts will help you select right probe for your application. You may e-mail your question to our distributor in your area or directly to APPNANO at info@appnano.com. 

 In case you want to switch probes to APPNANO HYDRA product, e-mail us the specs of your current probe and we will suggest you a replacement with similar specifications.

What is the advantage of having one cantilever per chip?

 One of the major applications of silicon nitride probes is to image soft samples in fluid. Most AFMs use only one cantilever to image at a time. The additional cantilever disturbs the sample while imaging. Though it gives flexibility to have more cantilevers per chip, ideally one cantilever gives best and true imaging.

 Do I have to buy FOUR different boxes to select right probe for my application?

 No, APPNANO supplies a combination box of all probes for new applications or new users.

Can I use silicon nitride probes on alignment chips?

 Yes, HYDRA probes have alignment grooves on the backside. These grooves fit in all alignment chips.

Silicon nitride is considered hard material. The current silicon nitride probes last much longer than silicon probes. How does HYDRA series compare with silicon nitride tips?

 The tip life time is primarily determined by the sharpness of the tip. Silicon tip with large tip radius of curvature is expected to last as long as silicon nitride tips of similar radius of curvature.

Are HYDRA probes compatible with my AFM ?

 Yes, Hydra probes are compatible with most AFMs.