CMOS-MEMS Gravimetric Biosensor

  John Neumann

Gary Fedder
Kaigham (Ken) Gabriel
Schematic showing a typical chemical treatment of a membrane with avidin (receptor) and biotin (target). The areal mass density of the CMOS-MEMS membrane is 2.6×103 ng/µm3; this is only about 200 times the areal mass density of bound biotin (1.5×10-5; ng/µm3), and much smaller than the vibrating mass in a quartz crystal microbalance.
Gravimetric sensing of chemicals in solution has traditionally been done with a quartz crystal microbalance, which detects chemicals via the change in frequency due to mass adhering to the surface. We propose to build the same type of functionality into a CMOS-MEMS device, which would have two distinct advantages over conventional technology:
  1. The CMOS-MEMS diaphragms, being on the order of 1 micron thick, have a small areal mass density, and thus should exhibit a large frequency shift when chemicals such as biotin, avitin, or DNA adhere.
  2. CMOS-MEMS allows us to economically build large arrays of individual sensors, which may be individually functionalized to respond to different chemicals. This, in addition to the possibility of performing sample mixing and transportation, would open up the possibility of creating very small, yet complex, "lab on a chip".



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