This paper reports the development of a low-cost, portable, light-emitting diode (LED)-based ultraviolet (UV) exposure system. The major system components include UV-LEDs, a microcontroller, a digital-to-analog converter, and LED control circuitry. Through its front panel with a liquid crystal display and keypad, the UV-LED lithography system is able to receive user-defined values for exposure time and power, which allows the exposure dose to be tunable on demand. Compared to standard mask aligners, the UV-LED lithography system is a fraction of the cost, is simpler to construct using off-the shelf components, and does not require a complex infrastructure to operate. Such a reduction in system cost and complexity renders UV-LED lithography a perfect candidate for microlithography with large process windows typically suitable for MEMS, microfluidics applications.
This paper reports the development of a low-cost, portable, light-emitting diode (LED)-based UV exposure system for photolithography. The major system components include UV-LEDs, microcontroller, digital-to-analog (D/A) converter and LED control circuitry. The UV-LED lithography system is also equipped with a digital user interface (LCD and keypad) and permits accurate electronic control on the exposure time and power. Hence the exposure dose can be varied depending on process requirements. Compared to traditional contact lithography, the UV-LED lithography system is significantly cheaper, simple to construct using off-the shelf components and does not require complex infrastructure to operate. Such reduction in system cost and complexity renders UV-LED lithography as a perfect candidate for micro lithography with large process windows typically suitable for MEMS, microfluidics applications.
Achieving real-time photoacoustic (PA) tomography typically requires massive ultrasound transducer arrays and data
acquisition (DAQ) electronics to receive PA waves simultaneously. In this paper, we report the first demonstration of a
photoacoustic tomography (PAT) system using optical fiber-based parallel acoustic delay lines (PADLs). By employing
PADLs to introduce specific time delays, the PA signals (on the order of a few micro seconds) can be forced to arrive at
the ultrasonic transducers at different times. As a result, time-delayed PA signals in multiple channels can be ultimately
received and processed in a serial manner with a single-element transducer, followed by single‐channel DAQ electronics. Our results show that an optically absorbing target in an optically scattering medium can be photoacoustically imaged using the newly developed PADL-based PAT system. Potentially, this approach could be adopted to significantly reduce the complexity and cost of ultrasonic array receiver systems.
Achieving real-time photoacoustic (PA) tomography typically requires multi-element ultrasound transducer arrays and their associated multiple data acquisition (DAQ) electronics to receive PA waves simultaneously. We report the first demonstration of a photoacoustic tomography (PAT) system using optical fiber-based parallel acoustic delay lines (PADLs). By employing PADLs to introduce specific time delays, the PA signals (on the order of a few micro seconds) can be forced to arrive at the ultrasonic transducers at different times. As a result, time-delayed PA signals in multiple channels can be ultimately received and processed in a serial manner with a single-element transducer, followed by single-channel DAQ electronics. Our results show that an optically absorbing target in an optically scattering medium can be photoacoustically imaged using the newly developed PADL-based PAT system. Potentially, this approach could be adopted to significantly reduce the complexity and cost of ultrasonic array receiver systems.
The scanning probe microscopy-based (SPM) lithography techniques have presented significant challenges in fabricating
nanostructures. Using this technique with assistance of pulse current, direct deposition or oxidation can be introduced on
material surfaces. In present research, we use an atomic force microscope (AFM) to write a solid (gold) feature onto a
substrate (silicon) in ambient environment. During the contact-sliding, the material on the gold (Au) tip transferred onto
the surface of the single crystalline silicon (Si). This transfer takes place atomically as shown on a smoothly worn Au tip.
This process is almost as simple as writing a line with a pencil. Dispersion of thermal energy inducted through friction is
discussed in this presentation.
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