View of the microcontact printer: (1) pneumatic actuator, (2) flexible coupler, (3) mobile head, (4) stamp holder, (5) red PDMS stamp, (6) substrate holder, (7) spray nozzle, (8) alignments of the substrate holder, (9) fiber optic, (10) camera zoom, (11) microscope slide substrate, (12) linear slide, (13) screws for the stamp/substrate parallelism, (14) screw for the adjustment of the load, and (15) machine frame that will be in contact with the screw 14.
Not to scale. (a) Stamp holder with stamp. [(b) and (c)] Sections of the stamp showing the lip, the thickness of the stamp that will be compressed and the feature height .
Stamp preparation station.
Actuation of the stamp movement. (a) Starting or home position. (b) Contact. The mechanical link between the stamp holder and the miniature linear slide is discussed in Sec. II D.
Top view of the mobile head carrying the stamp and principle of operation with: (1) two spherical bearings, (2) four micrometric screws, (3) four compressive springs, (4) carriage, and (5) suspended part. (a) Home position. (b) Initial contact between the stamp and substrate. (c) Flattening of the stamp.
Principle of the adjustment of load on the stamp with the two screws. (a) Before contact. (b) During contact.
Implementation of the screws for load adjustment in the microcontact printer. [(a) and (b)] Front and top views at home position. [(c) and (d)] Front and top views during printing: the screws are in contact with the machine frame linked to the carriage of the mobile head.
Lack of stability of the stamp movement in an early version of the microcontact printer. View of a stamp with circular features (background) in contact with a cross channel etched in a microscope slide (inverse background). The stamp and the substrate remain in place in the machine and the piston is actuated one time between image (a) and (b) causing a shift of the stamp.
with a single cross raised on the stamp surface (not to scale). The cross is viewed in the microcontact printer through the microscope slide substrate at two positions: stamp in contact and stamp away from the substrate. (a) Experimental setup. [(b) and (c)] Waveguide lighting. [(d) and (e)] Fiber optic lighting.
Progressive detachment of the cross when increasing screws length from contact position. (a) Initial position: stamp in contact with the substrate. (b) Final position: stamp away from the substrate. (c) Intermediate positions with increasing values of .
Principle of printing at the bottom of a microfluidic channel with a parallelepiped PMDS feature. (a) Inking of the stamp with fluorophore. (b) Transfer of corresponding to the contact area. The geometrical parameters are as follows: ; ; ; ; and . The length of the screws out of the stamp holder is adjusted so that .
View of the parallelepiped PMDS in contact with the bottom of the microfluidic channel (from the point of view shown in Fig. 12) (a)Fiber optic lighting. (b) Waveguide lighting. (c) Fluorescence of the substrate as scanned with an Axon GenePix® Personal 4100A scanner ( laser). The dashed lines correspond to the borders of the microfluidic channel.
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