14. DI water.
15. Piranha solution (70% H 2 SO 4 /30% H 2 O 2 , 50:50).
16. Bovine serum albumin (BSA) 0.1%.
17. 3-Trimethoxysilylpropyl methacrylate, Sigma-Aldrich.
2.2 Biochip
Encapsulation and
Centrifuge Holder
Fabrication
1. Poly(methyl methacrylate) (PMMA) plate, 1/8
00 thickness,
31.75 mm by 31.75 mm, four pieces per biochip
encapsulation.
2. Poly(methyl methacrylate) (PMMA) plate, 1/2
00 thickness,
20 cm diameter.
3. Drill bits, 1.016 mm (0.040
00 ), 2.36 mm (0.093
00 ’).
4. Milling tools.
5. CNC milling machine.
2.3 Centrifugal Cell
Trapping and
Electroporation
1. Phosphate buffered saline (PBS).
2. Cells, 200–300 in 5 μL suspension per device.
3. Nanoparticle encapsulated plasmid, 0.05 μg/μL.
4. Centrifuge, 45 Â g.
5. Palladium wires, 0.2 mm diameter, Invitrogen/Molecular
Probes.
6. Electronic pulser, Bio-Rad Gene Pulser Xcell electroporation
system.
3 Methods
The fabrication of the system includes two parts, the fabrication of
the biochip and the fabrication of the biochip encapsulation and the
centrifuge holder. Figure 2 shows a schematic of the main steps
involved in the fabrication.
3.1 Biochip
Fabrication
1. Soft lithography mold fabrication. The mold for soft lithography fabrication of microfluidic and microchannel array is fabricated by cleanroom based micromachining. A layer of
photoresist (SU-8) is spin-coated on a silicon wafer. The thickness of the photoresist can be in the range of 10 μm–30 μm
depending on the size of the cells to be trapped in the microfluidic device. After soft baking, UV exposure, and postexposure baking, the soft lithography mold will then be developed
by washing the unexposed photoresist. The details of this
step can be referred to the standard protocol of SU-8
photoresist [8].
2. Fabrication of microfluidic device stamp by soft lithography.
The next step is to fabricate PDMS stamps. Sylgard 184 PDMS
24
Lei Li
15. Piranha solution (70% H 2 SO 4 /30% H 2 O 2 , 50:50).
16. Bovine serum albumin (BSA) 0.1%.
17. 3-Trimethoxysilylpropyl methacrylate, Sigma-Aldrich.
2.2 Biochip
Encapsulation and
Centrifuge Holder
Fabrication
1. Poly(methyl methacrylate) (PMMA) plate, 1/8
00 thickness,
31.75 mm by 31.75 mm, four pieces per biochip
encapsulation.
2. Poly(methyl methacrylate) (PMMA) plate, 1/2
00 thickness,
20 cm diameter.
3. Drill bits, 1.016 mm (0.040
00 ), 2.36 mm (0.093
00 ’).
4. Milling tools.
5. CNC milling machine.
2.3 Centrifugal Cell
Trapping and
Electroporation
1. Phosphate buffered saline (PBS).
2. Cells, 200–300 in 5 μL suspension per device.
3. Nanoparticle encapsulated plasmid, 0.05 μg/μL.
4. Centrifuge, 45 Â g.
5. Palladium wires, 0.2 mm diameter, Invitrogen/Molecular
Probes.
6. Electronic pulser, Bio-Rad Gene Pulser Xcell electroporation
system.
3 Methods
The fabrication of the system includes two parts, the fabrication of
the biochip and the fabrication of the biochip encapsulation and the
centrifuge holder. Figure 2 shows a schematic of the main steps
involved in the fabrication.
3.1 Biochip
Fabrication
1. Soft lithography mold fabrication. The mold for soft lithography fabrication of microfluidic and microchannel array is fabricated by cleanroom based micromachining. A layer of
photoresist (SU-8) is spin-coated on a silicon wafer. The thickness of the photoresist can be in the range of 10 μm–30 μm
depending on the size of the cells to be trapped in the microfluidic device. After soft baking, UV exposure, and postexposure baking, the soft lithography mold will then be developed
by washing the unexposed photoresist. The details of this
step can be referred to the standard protocol of SU-8
photoresist [8].
2. Fabrication of microfluidic device stamp by soft lithography.
The next step is to fabricate PDMS stamps. Sylgard 184 PDMS
24
Lei Li