Time: 10:00am - 12:00pm Description:
Hu Group Meeting
Time: 12:00pm - 1:00pm Description:
-------- Microscale Manipulation of Cells and their Environment for Cell Sorting and Stem Cell Biology --------
Microsystems have the potential to impact biology by providing new ways to manipulate cells and the microenvironment around them. These microsystems provide the interface between the macro world and the micro world of cells. Simply physically manipulating cells or their environment--using microfluidics, electric fields, or optical forces--provides new ways to separate cells and organize cell-cell interactions. The interests of our lab are two-fold: 1) to develop ways of sorting cells and 2) to develop microsystems that manipulate cells and the environment in order to study embryonic stem cell self-renewal, differentiation, and reprogramming. In the first area, we have been developing methods that combine electrical and optical scattering forces to sort cells based on imaged spatial and dynamic information, enabling screens based upon complex phenotypic information. In the latter, we have developed microfluidic devices for modulating diffusible signaling between cells and for high efficiency electro-fusion of stem cells and somatic cells for studying fusion-induced cellular reprogramming.
Time: 4:00pm - 6:00pm Description:
Group Meeting
Time: 2:00pm - 5:00pm Description:
Tsu-Jae King Liu Grp Mtg
Time: 1:00pm - 2:00pm Description:
Prof. White Meeting
Time: 10:00am - 12:00pm Description:
Hu Group Meeting
Time: 12:00pm - 1:00pm Description:
Image resolutions of modern optical systems are many times limited by wavefront aberrations due to turbulence in the optical media. Adaptive Optics (AO) is a technology that utilizes a deformable mirror (DM) to correct the wavefront distortion, thereby enhancing the image resolution. In this thesis research, we investigate the design and fabrication of micromechanical-deformable-mirror arrays for AO applications.
Because the AO applications require large arrays (100s-1000s of segments) of closely-spaced deformable mirrors, it is desirable that the DM arrays can be integrated with CMOS control electronics. In this research, we develop a CMOS-compatible fabrication process for the DM arrays, in which polycrystalline-silicon-germanium (poly-SiGe) and polycrystalline-germanium (poly-Ge) are used as the structural and sacrificial materials, respectively.
One major challenge of using poly-SiGe as the structural material is to reduce the high strain gradient in as-deposited poly-SiGe films, because the low-thermal-budget requirement for post-CMOS integration prohibits the use of a high-temperature annealing step. In this research, the use of a bilayer structure to reduce the strain gradients of poly-SiGe is investigated.
The AO applications also require that the micromechanical deformable mirrors can provide large displacements (i.e. 10-20 um). In this research, we utilize the strain gradients of poly-SiGe to elevate the top plates of the parallel-plate mirror actuators, creating a large original gap for large-displacement actuations.
Using the technologies developed in this research, we demonstrate a 37-segment deformable-mirror array for vision-science AO applications.
Time: 4:00pm - 6:00pm Description:
Group Meeting
Time: 2:00pm - 5:00pm Description:
Tsu-Jae King Liu Grp Mtg
Time: 12:00pm - 1:00pm Description:
Lord Rayleigh studied the first elastic guided wave known as Rayleigh surface wave in 1885 and similar guided waves in a plate known as Rayleigh-Lamb waves in 1888. They were pure mathematical analyses. He noted, however, these waves may play an important role in earthquakes due to its limited divergence in two dimensions. In fact early studies on guided waves were mainly conducted in seismology. A variety of engineering applications have emerged after the World War II. For example:
(1) Ultrasonic non-dispersive delay lines for data storage and dispersive delay lines for signal processing.
(2) Resonators and filters for frequency control and selection.
(3) Non-destructive ultrasonic testing of surface defects and also defects in plates and pipes.
(4) Acoustic emission testing of pressure vessels.
A historical review will be presented with particular attentions to trapped energy modes of vibration and roles of complex branches of velocity dispersion equations in analyses of vibration and propagation.
Today
2pm>Tsu-Jae King Liu Grp Mtg