FREQUENTLY ASKED QUESTIONS
Download Flexstene Datasheet and FAQs.
1. Where can I shop for Flexstene products?
You can purchase Flexstene sheets online. Currently, only US orders are supported for online purchase. Please email us directly for international orders (minimum quantities apply). For Tax-Exempt organizations, please reply to the order confirmation email and send the tax id and proof of tax-exempt status for a refund of the tax amount. NOTE: If you have not received order confirmation or shipping notifications from InfineFlex, please remember to check your spam folder. For additional questions about your order, please contact us using the contact form or the phone number provided. Ask about discounts for large orders or custom orders (e.g. different dimensions or roll format).
2. What is the difference between Flexstene products?
Flexstene Basic is easily moldable and requires minimal pressure to create microstructures from your mold. It is recommended for open microfluidic chips, such as creating microposts for live cell immobilization. Flexstene Pro is adhesive and sticks very well to itself, glass, and some hard plastics through thermal bonding to seal your microfluidic devices. Flexstene Ultra thermally bonds to hard plastics for a tighter seal. Ultra is more physically durable than the other Flexstene products with higher tear and tensile strengths. Flexstene F is our most inert sheet with high chemical resistance and for sensitive assays. Below is a preliminary datasheet with our available sizes:
3. Which Flexstene product is right for me?
The field of microfluidics and microfabrication entails very diverse experiments. Hence, exhaustive types of experiments have not yet been performed with Flexstene. Thus, it is recommended to first purchase a variety pack of all current plastic grades to evaluate your specific experimental parameters on each product to see which product grade best suits your application. Among the applications, customers have performed immunoassays, nucleic acid analyses, oxygen gradients, cell immobilization, and cell cultures with Flexstene-based chips.
4. How do I mold Flexstene to be as transparent as possible?
We recommend molding Flexstene using a very smooth mold. That is, metal molds should have a mirror finish. Using glass or other transparent molds, such as epoxy or other silicones, will ensure a more transparent result.
5. How do you clean Flexstene?
Isopropyl alcohol, methanol, or distilled water may be used. Flexstene has to be dry (air or oven dried) before molding to avoid bubbling or splays (cloudiness). Tape is also recommended to remove dust particles. We recommend working with Flexstene in a clean room or under a laminar hood to minimize particle contamination.
6. Why do I keep getting tiny bubbles in the plastic when I mold with Flexstene?
Your setup is likely too hot or Flexstene is not completely dry. Lower the temperature, decrease molding time, air/oven dry Flexstene, or perform molding in a low humidity condition to minimize bubbling. It may take some trial and error to optimize micromolding with Flexstene on your particular setup.
7. How do I get rid of trapped air bubbles between my mold and Flexstene?
Increase the pressure applied to the molding process. It may take some trial and error to optimize micromolding Flexstene on your particular setup.
8. What is the most effective way to sterilize Flexstene?
Ethylene oxide, gamma irradiation, or autoclave will work. Please note that Flexstene products are not meant to be implanted in humans.
9. Do I need a heat press for Flexstene Basic?
No, a hot plate with a mold and Flexstene Basic pressed against that mold should suffice. Some customers include a small weight in the molding process.
10. Do I need a heat press for Flexstene Pro, Ultra, or F?
Yes. A press that can mold at a pressure of at least 30 psi or above is ideal. Most heat presses or hot embossers should work. You may have to make small adjustments to optimize molding your chips. We offer a dual sided heat press to achieve this.
11. How do I seal Flexstene microchannels to a substrate?
Flexstene should be thermally bonded at least 50ºC below its melting temperature at minimal pressure for several seconds. For example, Flexstene Pro can be sealed at 60°C to 100°C. Customers have successfully sealed Flexstene Pro by binding it to a substrate and storing the chip in an oven for minutes to overnight.
12. How do I create inlet and outlet holes for my microfluidic channels?
Traditional biopsy punches used with silicones will not work here. Using a rotary/hand punch or a laser cutter is recommended.
13. How do I prevent nonspecific binding?
Methods traditionally used to treat hard plastics generally work with Flexstene as well. For example, coating the surfaces with animal caseins or BSA (bovine serum albumin) has been used with success.
14. Which mold does Flexstene Basic/Pro work best with?
Common molds used in the field of microfluidics work well. These include fragile molds, such as photoresists (e.g. SU8), and etched glass molds. Temperature resistant epoxy molds and traditional metal molds (aluminum, nickel, brass molds) work also. Silicones such as PDMS work as well, however, be sure to choose a stiff silicone grade at least 20 Shore A durometers above the Flexstene grades (see datasheet for hardness levels of Flexstene grades).
15. Are Flexstene-based microfluidic chips used for cell culture?
While Flexstene is less permeable than PDMS, it still has sufficient air permeability to sustain certain cell cultures. Flexstene grades have successfully been used with yeast cells, NIH 3T3 fibroblasts, IPSCs (induced pluripotent stem cells), epicardium-derived cells, corneal cells, and other tumor cells. It is recommended to first purchase a variety pack of all current plastic grades to evaluate your specific experimental parameters on each product to see which product grade best suits your cell culture application.
16. What size range is reliably micromolded with Flexstene?
Between 5 µm and 1 mm is recommended with an aspect ratio (height to width) of 2:1 or less. However, submicron structures and higher aspect ratios have also been achieved by some customers.
17. How do I control the hydrophilicity of Flexstene surfaces?
Flexstene grades are only slightly hydrophilic. Hence, structures that optimize capillary flow (e.g. thin and long channels) will allow for wicking of aqueous fluids. To achieve more hydrophilic surfaces, strategies that have been used on hard plastics can also be applied to Flexstene surfaces. These strategies include plasma treatment or coatings with hydrophilic materials, such as poly (vinyl alcohol), polyurethane, polyacrylate, (hydroxypropyl) methyl cellulose, polyvinylpyrrolidone, or hyaluronic acid. Multiple vendors offer hydrophilic coatings through licensing models or outsourcing. Key points to consider are the cost structure, the type of coating, the coating application (e.g. dip, spray, spin, film coats), any curing step (e.g. UV or heat), and any post-processing steps (e.g. sterilization, cleaning, or storage conditions) that may affect your final chip. For hydrophobic surfaces, clients mold Flexstene structures with rougher surfaces (usually to attain air pockets at the submicron scale) to achieve hydrophobicity.
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NOTICE: These products are not for use in implantable medical or dental devices. All information and statements provided are assumed accurate and reliable. However, InfineFlex makes no guarantees, implied warranty for fitness for any purpose, or responsibility of any kind, expressed or implied. The datasheet shall not be used as an endorsement, recommendation, or permission to operate the products in any method that infringes on the intellectual property of another party. The user must also not assume that all safety precautions are presented, or that other measures may not be required. Last updated: 5/03/2019