The Nanoscale World

QNM, tip radius, deflection sensitivity and spring constant

rated by 0 users
Answered (Verified) This post has 1 verified answer | 2 Replies | 2 Followers

Top 200 Contributor
4 Posts
Points 52
Mads A.T. Hansen posted on Wed, Aug 25 2010 7:48 AM

I have just purchased 20 NPG-10 AU coated probes for QNM. The idea is to functionalise the tips and chemically map lignocellulosic surfaces.

Before mapping various calibration/estimation procedures are required: Tip radius, deflection sensitivity and spring constant. I have not received much training in the technique and mostly tried calibrating Biolevers that were too fragile, thus failing before actually engaging the tip.

Question: Would it be recommendable to calibrate/estimate the before-mentioned parameters before coating the tips - THEN coat the tips and engage to do the mapping?

Regards

Mads A.T. Hansen

  • | Post Points: 14

Answered (Verified) Verified Answer

Top 10 Contributor
280 Posts
Points 6,219
Bruker Employee

The key is to get the calibration parms for the measurement conditions.  If the coating will not effect the spring constant or tip end radius, you can do the calibration of those parms prior to coating.  You cannot pre calibrate the deflection sensitivity since that depends on the laser alignment.  In fact, you should do that measurement just before your experiments and in the same environment (in fluid if your measurement will be done in fluid).  Since the thermal tune requires the deflection sens, you might think that this means you have to calibrate the spring constant after that, but you can scale the spring constant later if you don't know the exact defl sens during the therma tune.

All Replies

Top 10 Contributor
280 Posts
Points 6,219
Bruker Employee

The key is to get the calibration parms for the measurement conditions.  If the coating will not effect the spring constant or tip end radius, you can do the calibration of those parms prior to coating.  You cannot pre calibrate the deflection sensitivity since that depends on the laser alignment.  In fact, you should do that measurement just before your experiments and in the same environment (in fluid if your measurement will be done in fluid).  Since the thermal tune requires the deflection sens, you might think that this means you have to calibrate the spring constant after that, but you can scale the spring constant later if you don't know the exact defl sens during the therma tune.

Answered (Not Verified) replied on Fri, Sep 17 2010 7:30 AM

Bede is right. Moreover, whether your tip is functionalized or not will not affect the spring constant except if there is a coating step, and in this case, it depends on the thickness of the added layer: if it's 10 nm of metal, it won't change anything to the spring constant but if it's 100 or several hundreds, this will impact on k, especially if you use soft levers (0.006 to 0.06 N/m).

Alex.

  • | Post Points: 10
Page 1 of 1 (3 items) | RSS
Copyright (c) 2011 Bruker Instruments