Basic Surface Micromachining Process Sequence I. Deposit Sacrificial Layer II. Pattern Sacrificial Layer III. Deposit Mechanical Layer IV. Pattern Mechanical Layer V. Release Mechanical Layer VI. Test Device +V
Microfluidic Devices Microfluidic devices are MEMS devices with micro-scale (10 -6 m) or nano-scale (10 -9 m) flow channels They come with valves, electrodes, heaters, and other features These microfluidic devices can be used as tiny chemical processing or reaction system, consuming only tiny amount of chemical – micro-TAS (micro total analysis system)
Comparison with the conventional detection on slides On slides –9 steps –Takes more than 1 h –Consumes 20µl cells solution and 25 µl labeling reagent Within filter chip –3 steps –Takes less than 0.5h –Consumes 2 µl cells solution and labeling reagent
Quantum Dots Labeling of C. parvum (red) and G. Lamblia (Green) Quantum Dots as a Novel Immunofluorescent Detection System forCryptosporidium parvum and Giardia lamblia, L. Zhu, S. Ang, & Wen- Tso Liu, in Applied and Environmental Microbiology.
What is a Bio-Sensor? Biologically sensitive Material –Antibodies –Enzymes –DNA Probes Transducing Element/System –Electrochemical –Optical –mass Interfacing –Fluorescent –Chemiluminescent –Enzymatic substrate Direct Indirect
E-coli Sensing Principle Au Electrode E. coli O157:H7 cells Fe[(CN) 6 ] 3-/4- Charge transfer is blocked Streptavidin Self Assembled Monolayer
E-coli cells on the surface of bio-sensor before washing away non-specific binding - 65 x 100 μm window size 1000 X Magnification Scanning Electron Micrograph of E-Coli on Bio-Sensor
Extracellular Field Potentials in Olfactory Bulb of A Male Rat Stainless steel microwires - 100 µm diameter, enamel-insulated 16-site brain microprobe A) Match in evoked potential amplitude and waveform across the fourrecording sites when occupying the same position in the olfactory bulb B) Sharp reversal of polarity as each recording site across the mitral cell later,indicating that crosstalk between channels is minimal.