Novascan AFM Probes: Frequently Asked Questions (FAQ)

1.1 What is the minimum order for modified AFM probes and surfaces?

Our minimum order for modified probes and surfaces is five for any given modification type based on particle size and/or chemical modification. For example, if you need to order probes with 5um and 10um particles you would need to order ten probes in total, five for each particle size. The same is true for chemically modified products; you would need to order five of each specific chemistry.

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1.2 What payment methods do you accept for AFM probe purchases?

The suggested payment method is by credit card or prepayment. We accept Visa, MasterCard, American Express and Discover. Prepayment can include bank wire or check. Any of these approaches will automatically qualify you for a prepayment discount of 15%. Please inquire if prepayment is not a possibility.

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1.3 How do I place an order for custom AFM probes?

Orders may be placed by phone, email or fax. When using a purchase order number, an official copy of the PO must be sent via email or fax. When ordering, you will need to provide the following: billing and shipping addresses, method of payment and product information including all specifications. Required specifications may include particle type, particle size, desired chemistry and cantilever requirements. Credit card purchases will require the card type, number, expiration date and three-digit security code.

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1.4 What is the typical lead time for modified AFM probe orders?

The PSL processes orders as soon as order payment is established. The standard shipping turnaround time is 7-10 days from receipt of credit card information, approval of NET30 terms or receipt of a university check. Often times, we are able to complete the modifications in less time. Custom orders may take longer depending on the availability of particles or reagents.

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1.5 Can I expedite my AFM probe order?

When possible, we can put a rush designation on orders. However, please remember that many of our modification protocols take more than one day to complete. Also, large orders are difficult to rush due to the time required to process them. In that instance, it might be best to arrange for multiple shipments.

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1.6 Do you offer standing orders for AFM probes?

Yes, the PSL does offer standing orders. In many cases we recommend this approach, especially if you are ordering a large number of chemically modified probes. Standing orders are paid in advance with 2 more shipping charges to cover multiple shipments. These shipments may be scheduled in advance or held until requested. Standing orders may qualify for both prepay and volume discounts. Please contact the PSL if you are interested in establishing a standing order.

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1.7 How do I request a quotation for AFM probe modifications?

Please request a quote here. This information can also be provided by sending a request to info@novascan.com.

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1.8 How long is my AFM probe quotation valid?

Quotations are valid for 30 days. If your quotation is older than 30 days contact the PSL at info@novascan.com to receive a new one.

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1.9 Do you offer group discounts on AFM probe purchases?

Multiple researchers from the same institution ordering together will qualify for group discounts provided the total number of purchased modifications totals 50 or more. Group discounts will vary with the type and number of modifications requested. Please contact info@novascan.com for further information regarding group purchases.

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1.10 Can I get free samples of your modified AFM probes?

Unfortunately, the cost of cantilevers and reagents as well as the time required to perform the modification protocols preclude us from being able to provide free samples. To counteract this, Novascan maintains a low minimum order level of five for each specific modification.

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2.1 What is the shelf life of chemically modified AFM probes?

Because chemically modified probes and surfaces have a limited shelf life we prepare them only as they are ordered. We suggest that you open the product packaging only when you are prepared to start your application. Once the package is opened it is important to store the probes as recommended. Doing so will extend the lifetime of your probes or surfaces to over a month. Chemically modified products not stored correctly will have shorter lifetimes.

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2.2 Which side of your gold-coated AFM probes is coated?

Our gold coating is applied to the tip or functional side of the cantilever. The silicon nitride probes that we modify already have a reflective side gold coating.

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2.3 Is your gold coating on AFM probes atomically flat?

Our gold surfaces are not atomically flat. They have expected rms values of 2-3nm. These surfaces can be annealed using flame or oven protocols. This process will result in islands of atomically flat gold.

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2.4 What particles are available for AFM probe modification?

Novascan maintains a large inventory of standard particles for AFM probe modification. A description of these particles appears in our Probe Modification Brochure, a link to which appears on Probe Modification product page within this site. If you do not see your particle of interest, do not hesitate to contact Novascan to discuss the possibility of performing a custom particle modification.

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2.5 Do your particle sizes refer to diameter or radius?

The particle sizes quoted refer to the diameter of the particles.

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2.6 How do you minimize silicon oil contamination in AFM probe packaging?

The PSL’s new and innovative approach to probe packaging takes special steps to reduce the silicone oils present in standard storage boxes.

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2.7 How are cantilever spring constants designated?

The PSL modifies commercially available silicon and silicon nitride AFM probes. Unless specific calibration is requested, the manufacturer reported spring constant is the value provided. It is important to consider that these values can vary by more than 50% so strong consideration should be given to requesting calibration of modified cantilevers.

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2.8 Should I calibrate my modified AFM probes?

Because manufacturer reported spring constants might have errors of over 50%, calibration should always be a consideration. This option reduces the expected error to 10% or less. Applications requiring force measurements are especially strong candidates for receiving cantilever specific calibration. For current pricing information for the PSL’s calibration services, please contact info@novascan.com.

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2.9 Can I calibrate used AFM probes?

In most cases, used probes may be calibrated. It is important to consider how the conditions under which the probes were used can affect the calibration value. For instance, probes used in a salt solution should be immediately cleaned following use to prevent salts from drying on the cantilever. Likewise, large amounts of contamination should also be eliminated via a standard cleaning regime. Provided the cantilever is intact and relatively clean, an accurate calibration may be obtained.

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2.10 Are all cantilevers modified in particle probe orders?

Standard particle modifications involve the attachment of a particle to only one cantilever per probe. However, the PSL has performed custom modifications that included the mounting of multiple particles. These custom modifications have included the attachment of as many as eight particles to single sided cantilever arrays. If you have an application requiring multiple particle mountings, please contact the PSL at info@novascan.com for feasibility and pricing.

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2.11 What if you don't stock my desired AFM cantilever?

The PSL stocks commercially available silicon and silicon nitride probes for chemical or physical modifications. Should your application require the modification of a probe not carried by Novascan, arrangements can be made for the use of other probes. The purchase of non-inventory probes can be included in your order. Likewise, you may provide probes that you are already in possession of. Particle modifications may require the use of tipless cantilever. In this instance, please discuss your modification request with a PSL technician.

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2.12 What reflective coating do you recommend for modified AFM probes?

The main issue to consider with regard to reflective backside coatings is whether your application will be performed in air or in fluid. Most silicon nitride probes have a backside reflective coating of gold, which performs well in either condition. However, silicon probes often have standard reflective coatings of aluminum. Aluminum has been demonstrated to be unstable with extended exposure to some solutions. Therefore, our recommendation is to use a gold reflective backside coating on silicon probes intended for use in solution.

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2.13 What do you recommend for hydrophobic and hydrophilic AFM probes?

The PSL has several methods available for creating hydrophobic and hydrophilic AFM probes. One approach is to simply attach a borosilicate particle (hydrophilic) or a polystyrene particle (hydrophobic). Another approach involves standard probes that are chemically modified using alkanethiol self-assembling monolayers. The most common chemistries are methyl (hydrophobic) and carboxyl (hydrophilic) monolayers. It is also possible to apply either of these chemical modifications to glass particles mounted on cantilevers.

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2.14 Can you mount customer-provided particles on AFM probes?

Yes, in most cases that is a viable option for modifying your cantilevers. However, custom particle modifications will often require sending a small sample of the particles to the PSL for review.

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2.15 What antibodies do you have for AFM probe modifications?

The PSL performs many AFM probe/antibody conjugations. However, we do not maintain an inventory of antibodies. Conjugations are performed with antibodies supplied by the client. Please contact the PSL for the amount and concentration of antibody required for a given modification.

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2.16 What characterization do you perform on chemically modified AFM probes?

We limit specific order characterization for several reasons. First, individual order characterization would be quite costly thereby increasing the price of probe modifications significantly. Secondly, the well-established and straightforward chemical conjugations used to complete these modifications do not require repeated characterization. Finally, characterization would destroy and or contaminate the modifications on the probes. That being said, we often perform a very simple test that demonstrates that the surface chemistry has changed without affecting the stability or usability of the modified probes. This method demonstrates that the surface has been changed.

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