The use of acoustic energy to manipulate particles and cells (acoustophoresis) is a well-studied and popular technique in microfluidic microscopy applications. This powerful and gentle method has typically required the construction of costly and labour intensive resonating chambers. A new fabrication method for acoustophoretic resonators is presented, using inexpensive materials and without the need for cleanrooms or the special equipment typically found within them. By utilizing a simple glass and polyimide sandwiching technique, single, bifurcating, and trifurcating microchannels were built and tested. Various half and full wavelength transversal resonators were established in microchannel widths of 300, 600, and 750 μm using 1, 2.5, and 5 MHz ultrasound. In significantly simplifying the fabrication and prototyping of these microfluidic resonators we hope to address some of the major drawbacks preventing acoustophoresis technology from being incorporated into the toolkits of laboratories around the world.
We report results from a proof-of-principle study investigating a technique for high-resolution imaging of large fields of view (FOV). This is achieved through structured illumination of the sample from a laterally replicated spatial light modulator (SLM). By incorporating the SLM into the illumination path of an otherwise conventional microscopy imaging system, we can perform the sampling by using our illumination source instead of our areal detector (camera). The increased resolution is achieved through anti-binning or splitting of the charge-coupled device (CCD) pixels, and the extended FOV is obtained by a lateral replication technique applied to the whole illumination field. With anti-binning, we effectively exceed the sampling resolution limit set by the Nyquist theorem. Also, our lateral replication technique enables us to maintain the same FOV for the increased resolution without the need for adaptive optics or highly corrected lenses far from the optical axis. The two techniques of resolution enhancement and lateral replication of the illumination field could be employed independently, hence offering increased versatility and adaptability for specialized imaging applications. Different imaging modes can be accessed digitally, without the need to change objectives, stitch together individual frames, or move the sample. The resulting imaging modality of this system is quasi-confocal.
This paper presents a novel 2D-scanning micro-mirror used in ECOM for in vivo and in situ tissue imaging using MEMS technology. The 2D scanner accomplishes Raster Scanning with just one mirror. The size of the mirror is 1mm by 1mm and is rotated about two axes giving it two degree of freedom. The scanning mirror is actuated electrostatically. The inherent disadvantages of electrostatic actuation such as high crosstalk between electrodes, and large nonlinearity in voltage to angle relationship are systematically addressed. In the context of biomedical applications, it is desirable to minimize the driving voltage requirements of the electrostatic actuators while maintaining the same scan angle. The optical scanner described in this paper is capable of generating large scan angles with low driving voltages, thus making it highly suitable for biomedical imaging.
SOI wafers are finding increasing applications in MEMS devices. The device Si, buried oxide, and handle Si layers provide mechanical and structural properties to create more complex 3D free standing structures. This paper presents the fabrication process of double-sided mirror by using surface and bulk micromachining of SOI wafers. Silicon nitride thin firms are deposited on device layer of SOI to provide torsion bar material of the mirror. Device layer provides single crystal Si mechanical reinforcement to counteract the stress associated with silicon nitride. The underlying buried oxide acts as an etch-stop layer during DRIE of the Si handle layer and sacrificial layer for releasing the torsion bars. The dimensions of the mirror are 250um by 500um suspended by two torsion bars that are 350um by 6um by 0.4um.