title: Virtual microwells for digital microfluidic reagent dispensing and cell culture.
abstract: Digital microfluidic (DMF) liquid handling includes active (electrostatic) and passive (surface tension) mechanisms for reagent dispensing. Here we implement a simple and straightforward Teflon-AF liftoff protocol for patterning hydrophilic sites on a two-plate device for precise passive dispensing of reagents forming virtual microwells--an analogy to the wells found on a microtitre plate. We demonstrate here that devices formed using these methods are capable of reproducible dispensing of volumes ranging from ~80 to ~800 nL, with CVs of 0.7% to 13.8% CV. We demonstrate that passive dispensing is compatible with DMF operation in both air and oil, and provides for improved control of dispensed nano- and micro- litre volumes when compared to active electrostatic dispensing. Further, the technique is advantageous for cell culture and we report the first example of reagent dispensing on a single-plate DMF device. We anticipate this method will be useful for a wide range of applications--particularly those involving adherent cell culture and analysis.
authors.affiliation: Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada.
authors.forename: Irwin A
authors.initials: IA
authors.lastname: Eydelnant
authors.forename: Uvaraj
authors.initials: U
authors.lastname: Uddayasankar
authors.forename: Bingyu
authors.initials: B
authors.lastname: Li
authors.forename: Meng Wen
authors.initials: MW
authors.lastname: Liao
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Wheeler
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D018929:Cell Culture Techniques / Q000295:instrumentation* / Q000379:methods; D002460:Cell Line; D004285:Dogs; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D055672:Static Electricity