title: Piezoresistive cantilever based nanoflow and viscosity sensor for microchannels.
abstract: Microfluidic channels are microreactors with a wide range of applications, including molecular separations based upon micro/nanoscale physicochemical properties, targeting and delivery of small amount of fluids and molecules, and patterned/directed growth. Their successful applications would require a detailed understanding of phenomena associated with the microscale flow of liquids through these channels, including velocity, viscosity and miscibility. Here we demonstrate a highly sensitive piezoresistive cantilever to measure flow properties in microfluidic channels. By milling down the legs of the piezoresistive cantilevers, we have achieved significantly higher mechanical sensitivity and a smaller spring constant, as determined by AFM. These cantilevers were used in microchannels to measure the viscosity and flow rate of ethylene glycol mixtures in water over a range of concentrations, as well as of low viscosity biologically relevant buffers with different serum levels. The sensor can be used alone or can be integrated in AFM systems for multidimensional study in micro and nanochannels.
authors.affiliation: Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA 93106, USA. Lal@lifesci.ucsb.edu
authors.forename: Arjan
authors.initials: A
authors.lastname: Quist
authors.forename: Ami
authors.initials: A
authors.lastname: Chand
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Ramachandran
authors.forename: Dan
authors.initials: D
authors.lastname: Cohen
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Lal
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002021:Buffers; D002417:Cattle; D019855:Ethylene Glycol / Q000737:chemistry; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D008855:Microscopy, Electron, Scanning; D012680:Sensitivity and Specificity; D044967:Serum / Q000737:chemistry; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D002021:Buffers; D014867:Water; D019855:Ethylene Glycol