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This work proposes using a periodic and reversible DEP (dielectrophoresis) field to improve the immuno-capture efficiency of the rare specific cells in a mixed cell suspension. The forward DEP field gently guides all the cells to interact with the bioprobes that are immobilized on a PVDF substrate in the reactor, and the reverse DEP field redistributes the un-bonded cells into the suspension for next reaction chance. The fluorescence visibility of the specific T-cells was also improved via quantum dots/tetramer complex staining. Accordingly, the specifically stained and captured cells could be imaged and counted. The experimental results indicated that the forward DEP can double the cell-capture efficiency compared with that without DEP enhancement, and the reversible DEP scheme can improve the efficiency about 25% further. This assay is also successively used to detect the population of rare cytotoxic Tc cells in a human blood sample; and the Tc cell has specific receptors on the membrane surface to identify the Epstein–Barr virus (EBV).

We propose the first time combining the merit of scanning and immersion lithography to fabricate 3D microstructure in this study. Via applying a matching liquid to reduce the diffraction error, the gap between the mask/resist becomes more tolerable. In addition, the liquid also act as a lubricant and a buffer for smooth movement of the mask/substrate. These advantages will benefit the performance of scanning lithography technique. The experimental results show that the large-area, 3D microstructure with excellent surface quality (R avg ≪10 nm) can be successively fabricated based on this method. Besides, 3D microstructures with various geometries and functionalities can be generated by altering the shape of the mask pattern, or changing the scanning directions. The proposed SIL technique seems to be a promising way for fabricating 3D microstructure for optical applications.

This paper proposes using a weak DEP field, gently guiding the cells in the suspension to interact uniformly with the bio-probes immobilized on the PVDF substrate in the reactor. Due to the concentrating effect of the weak DEP field, together with relative-large reaction area, the cell-capture efficiency can be improved 4 folds compared with that without DEP enhancement. The visibility of the specific T-cells was also realized via QDs/tetramer staining. In consequence, the captured cells can be fluorescence imaged and counted by image processor. This assay has been successively used to detect the rare specific Tc cell in human blood sample, which recognize and destroy the Epstein-Barr virus (EBV). Preliminary results show that the capture efficiency of the DEP+ cell capture technique is as good as around 40%.

SU-8 resist was used as a core/cladding waveguide material to fabricate a Mach-Zehnder interferometer (MZI) for biochemical sensing. The refractive index and the UV lithography processes of the SU-8 resist were optimized to give a SU-8 MZI chip with single-mode and high-efficiency transmission. Optical measurements reveal that the SU-8 MZI chip can transmit the NIR laser (/spl lambda/=1310 nm) with a total loss less than 6 dB. The bio-probes (rabbit IgG) were then immobilized on the surface of the SU-8 waveguide. When one branch of the MZI is in contact with the analyte (sheep anti-IgG), the interfered intensity changes accordingly and then stabilizes when the soaking time extended. The MZI chip is very sensitive and a dilute anti-IgG solution with a concentration as low as 10/sup -15/ g/ml can be detected. The polymer MZI chip is fabricated by molding (or LIGA) process. The low-cost, label-free, real-time and high-sensitivity MZI chip benefit many applications related to biological, environmental and industrial detection.

High average power millimeter wave sources are being developed in a collaboration between SLAC and CPI. CPI has developed a number of high-power, broadband, millimeter-wave, CCTWT amplifiers. The coupled cavity technology is now approaching the limits for generating power at millimeter wave frequencies. To generate significant increases in power, other technologies need to be considered. At SLAC, compact, lightweight, PPM-focused, klystrons, nicknamed 'klystrinos' are being developed, using lithographic fabrication methods (LIGA). These devices will operate at 100 kW peak power and 1 kW average power at 95 GHz. Two design areas are critical to the success of the klystrino. First is the electron beam optics and beam focusing. A beam tester is being built to evaluate the electron gun and the PPM focusing system. Results of the beam tests are presented. CPI has analyzed the electron gun and is investigating the addition of a control electrode for improved modulator efficiency. The second significant design area is the modeling of the klystrino. The combination of the rectangular LIGA structure and the multiple gap output section make modeling the klystrino difficult. MAFIA and MAGIC have been used to develop an equivalent 2D model of the 3D LIGA circuit. Thermal capacity of the circuit is also investigated at CPI using the ANSYS 3D FEA code. The analysis included both the expected RF losses and beam interception. The calculations include both transient response and steady state. The thermal analysis is used to predict the maximum allowable beam interception and duty cycle that the circuit can withstand without major problems.

The design and fabrication issues arising from the development of a 94 GHz, 100 kW klystron are discussed. The klystron beam is focused using periodic permanent magnets that are mounted in the vacuum envelope. Several circuit fabrication processes were considered before the “LIGA” lithographic process was chosen. LIGA has the dimensional tolerances and surface finish required for klystron operation at 94 GHz.