Flow Cell Materials

CiDRA® Precision Services, LLC uses the right materials and flow cell construction technology for the application.  Whether designing a flow cell for extreme environment industrial applications or for life sciences consumables, CiDRA® Precision Services, LLC has the material and manufacturing technology to make your project a success.

Although CiDRA® Precision Services, LLC manufactures flow cells in many optical and non-optical materials, the vast majority of the applications we encounter involve borosilicate glass, fused silica, sapphire and silicon.  Detailed material property lists for all of these materials can be found in our materials data base, but below is a simple design guideline for engineers in the beginning stages of the design process.  Note that PDMS has been added to the list because SlipStream™ flow cells use this material in combination with the others.

 

Sapphire

Fused Silica

Silicon

Borosilicate

PDMS
Cost Most Expensive Expensive Expensive Inexpensive Inexpensive
Max Use Temp ~2000 ~1050 ~1300 ~230 ~200
Thermal Conductivity(W/(m K) ~35 ~1.3 ~145 ~1.1 ~0.15
CTE (1/C x 10e-6) ~5.5 ~0.4 ~3.5 ~3.3 ~312
Hardness (Knoop) ~2050 ~600 ~1100 ~450 N/A
Ease of Polishing Difficult Easy Easy Easy N/A
Auto fluorescence High Very Low None Low Low(**)
Transmission Range
(um)		 0.3-3.5 0.18-2.4,
3-3.5		 1.5-8 0.3-2.0 0.25-1.2

(*) Physical properties depend on crystalline orientation.
(**) At 633nm the autofluorescence is approximately the same as borosilicate glass but at lower wavelengths the autofluorescence is 2 to 3 times higher than borosilicate glass.

The properties of the materials provided in this table vary considerably, making it possible to cover a broad application space with judicious material choices. 

  • Sapphire is by far the most expensive and difficult to work with, and has the highest auto fluorescence.    However, this material is well suited for harsh environments, chemicals and temperatures that do not involve fluorescence-based measurement systems.   
  • Silicon does not fluoresce, so it is an excellent background plate for flow cells used in fluorescence-based instruments.  However, Silicon does not transmit visible light so must be used in conjunction with glass to produce closed cells.  
  • Borosilicate glass is by far the least expensive material to work with, and its polishing and machinability are on par with silicon and fused silica. 
  • Fused silica is the right choice when visible transmission and low autofluorescence are driving the flow cell design.  Because it is very expensive to etch fused silica, flow cells made from this material are either machined or made using SlipStream™ technology. 
  • PDMS is used to assemble SlipStream™ flow cells.  Its low cost, low fluorescence and ability to bond to most flow cell materials makes it very attractive for many applications.  Its high CTE must be considered with working with very thin (~100um to ~200um) glass.