The atomic force microscope (AFM) is one kind of scanning probe microscopes (SPM). SPMs are designed to measure local properties, such as height, friction, magnetism, with a probe. To acquire an image, the SPM raster-scans the probe over a small area of the sample, measuring the local property simultaneously.
Asylum Research MFP3D-BIO-
Asylum Research MFP3D-BIO is a very versatile atomic force microscope, suitable for use with a wide range of samples and features a vast array of modes. It has a z-range of 40 um (extended head model) and an x and y movement of up to 90 um in a closed loop scan. The microscope differs from most others available on the market due to using seperatepiezos for each plane. This allows for the use of nano-position sensors, minimising hysterisis and creep, whilst also ensuring flat scans. The MFP-3D is able to image conductive, semiconductive and insulating samples in both air and liquid environments. The head can be adjusted to fit a wide range of sample sizes and both top down and bottom up illumination of samples is possible.
Some Features of Asylum Research MFP3D-BIO
Working of AFM
An AFM image is typically comprised of a signal representing some Z distance of cantilever motion per X,Y point on the scan raster . These signals can be from various measurement points in the instrument: the voltage to move the Z piezo actuator in response to the feedback loop; the closed loop sensor monitoring the movement of the top plate of the optical lever detector; the amplitude, phase or deflection signal from the position sensitive detector; or some kind of error in the feedback loop. All signals are typically read as a voltage in the MFP3D system.
Intermittent contact mode
This technique drives the cantilever just off its fundamental resonant frequency at some user defined amplitude set point, typically some dampened value of the ‘Free Air’ amplitude of the cantilever. This set point is read as a voltage off the PSD. The feedback loop maintains this setpoint amplitude (voltage) as the tip is scanning across the surface, retracting the Z piezo when the amplitude gets dampened (bumps); or extending the Z piezo when it oscillates at a larger amplitude than the amplitude set point (over holes). The latter is why the set point must be a dampened amplitude ratio of the ‘Free Air’ ratio.
Contact Mode -
In this mode, the tip is in full contact with the surface as the sample is rastered in a XY pattern while maintaining a user defined deflection voltage (i.e., force) to keep a positive deflection on the cantilever. Depending on how soft the sample is, and what forces are being applied, the technique can be more destructive than AC mode. However, this technique is great for hard surfaces, or imaging cells in fluid at very low set point forces.
Force Spectroscopy:
Force spectroscopy measures the deflection (displacement) of the cantilever (with known spring constant) in the Z direction with the intent that an adhesion dissociation event between the tip and substrate will be measured, or the compliance of a material under the ‘tip’ as it pushes into it. The process usually begins with the tip approaching the surface with some ‘free air’ (non-contact) deflection value, make contact to the sample for some period/ load until it reaches a user defined cantilever deflection (force), to then reverse direction for the retract cycle (although there are some exceptions).
There are two major classifications that most force spectroscopy experiments measure:
A. A pulling event in which the tip interacts with the surface, and some adhesion dissociation event between the tip and surface is measured on the retract cycle.
B. The tip pushes into the surface to measure compliance.
Samples for AFM
Here are some guidelines for AFM analysis:
1. Registration process (One Time): New Registration for external users.User Verification: Upload photo of Front side and back side of valid Identity card issued by the organization (only .jpeg format, file Size less than 1 Mb, height less than 1000 pixels, width less than 800 pixels). Undertaking: Download the undertaking template ( Download Link ). Duly filled, signed and stamped form should be uploaded in .pdf format. Confirmation: An email will be sent to the user after verification of the documents.
2.Before planning to avail the Instrument facility of CRF IIT Delhi: user must visit https://crf.iitd.ac.in -> Facility -> select the desired facility from left side navigation list. Read carefully all the relevant information such as required sample type, testing charges and instrument location. Be prepared with details of the samples.
3.Log in and Click on Booking Appointment Tab: All the information relevant to testing must be filled in instrument booking form. In case user does not provide the required information the booking is liable to be rejected. User can upload the relevant existing data of their samples that might help in the measurements.
4.Sample submission & Payment Process: Once the application is submitted, the in-charge will verify the details and approve the request.External users must wait for the approval before making the payment and submitting the samples to concerned lab. After approval the payment should be made by the user. The payment transaction details need to be submitted online before appointment date time.
5.CRF Users can pay amount online using following details:
Beneficiary/Customer's Name: IRD ACCOUNT IITD
Bank Account Number: 10773572600
Bank Name: State Bank of India Branch Name: IIT Branch
Branch Code: 01077
NEFT IFSC CODE / RTGS: SBIN0001077
please write "CRF _Instrument Name" in the Remarks section while paying. Save the receipt file and upload in the crfbooking system online against your application.Payment can also made in form of demand draft in favour of " IRD ACCOUNT IITD " Payable at New Delhi.6.IIT Delhi
GST Number : 07AAATI0393L1ZI
PAN Number : AAATI0393L
1 Registration process (One Time): New Registration for internal users.
Fill in all the details in Personal Information, Supervisor Information and User Login Credentionals.
Once submitted, an email to supervisor is sent for activation of account. Once activated by supervisor, you can do the instrument bookings.
2 Before planning to avail the Instrument facility of CRF IIT Delhi: user must visit https://crf.iitd.ac.in > Facilities > select the desired facility from left side navigation list. Read ca 
refully all the relevant information such as required sample type, testing charges and instrument location. Be prepared with details of the samples.
3. Log in on CRF Booking System and Click on Booking Appointment Tab: All the information relevant to testing must be filled in instrument booking form. In case user does not provide the required information the booking is liable to be rejected. User can upload the relevant existing data of their samples that might help in the measurements.
4 Sample submission & Payment Process: Once the application is submitted, the in-charge will verify the details and approve the request.
