Packaging is used to protect and enable intelligent sensor systems utilized in manned/unmanned ground vehicle systems/subsystems. Because Micro electro mechanical systems (MEMS) are used often in these sensor or actuation products, it must interact with the surrounding environment, which may be in direct conflict with the desire to isolate the electronics for improved reliability/durability performance. For some very simple devices, performance requirements may allow a high degree of isolation from the environment (e.g., stints and accelerometers). Other more complex devices (i.e. chemical and biological analysis systems, particularly in vivo systems) present extremely complex packaging requirements. Power and communications to MEMS device arrays are also extremely problematic. The following describes the research being performed at the U.S. Army Research, Development, and Engineering Command (RDECOM) Tank and Automotive Research, Development, and Engineering Center (TARDEC), in collaboration with Wayne State University, in Detroit, MI. The focus of the packaging research is limited to six main categories: a) provision for feed-through for electrical, optical, thermal, and fluidic interfaces; b) environmental management including atmosphere, hermiticity, and temperature; c) control of stress and mechanical durability; d) management of thermal properties to minimize absorption and/or emission; e) durability and structural integrity; and f) management of RF/magnetic/electrical and optical interference and/or radiation properties and exposure.
It is possible to dramatically improve the performance, reliability, and maintainability of vehicles and other similarly complex equipment if improved sensing and diagnostics systems are available. Each year military and commercial maintenance personnel unnecessarily replace, at scheduled intervals, significant amounts of lubricant fluids in vehicles, weapon systems, and supporting equipment. Personnel draw samples of fluids and send them to test labs for analysis to determine if replacement is necessary. Systematic use of either on-board (embedded) lubricant quality analysis capabilities will save millions of dollars each year in avoided fluid changes, saved labor, prevented damage to mechanical components while providing associated environmental benefits. This paper discusses the design, the manufacturing, and the evaluation of robust optical sensors designed to monitor the condition of industrial fluids. The sensors reported are manufactured from bulk fused silica substrates. They incorporate three-dimensional micro fluidic circuitry side-by-side with three-dimensional wave guided optical networks. The manufacturing of the optical waveguides are completed using a direct-write process based on the use of femtosecond laser pulses to locally alter the structure of the glass substrate at the nano-level. The microfluidic circuitry is produced using the same femtosecond laser based process, followed by an anisotropic wet chemical etching step. Data will be presented regarding the use of these sensors to monitor the quality of engine oil and possibly some other vehicle lubricants such as hydraulic oil.
The fabrication parameters necessary for the development of waveguides that transmit energy from deep ultraviolet to infrared range on wide band gap semiconductor thin film is discussed. Such waveguides in conjunction with microfluidic systems may be used for a spatial and temporal drug delivery in neural tissue. These waveguides may also be suitably modified and employed for novel applications like lab-on-a-chip technologies for Raman Spectroscopy and high speed telecommunication optical switches. Highly textured AlN thin films are grown on C-plane sapphire with high refractive index buffer layer by plasma source molecular beam epitaxy (PSMBE). Analytical measurements such as atomic force microscopy (AFM), ultraviolet spectroscopy and X-ray diffraction, were used to characterize surface morphology and crystalline structure of these films. The fabrication of waveguide structures was performed using laser micromachining with a KrF Excimer laser of wavelength 248 nm and pulse duration of 25ns. Waveguide etching rate for the AlN thin films is investigated as a function laser pulse energy and number of pulses. It is found that etching rate increases almost linearly with both--the pulse energy and number of pulses.
The index of refraction of most glasses can be permanently changed by exposure to femtosecond laser pulses. This effect allows for the fabrication of various two-dimensional or three-dimensional light guiding structures. Passive and active optical devices have been manufactured using this femtosecond direct-write technique. A closely related technique has recently been demonstrated to manufacture three-dimensional microfluidic networks.
We describe recent work at Translume and RPI in femtosecond direct write to produce devices which incorporate on a single glass chip optical network with microfluidic network.
On the battlefield and on the home front there exists an increased Nuclear, Biological, and Chemical (NBC) threat. There has been an ongoing effort to develop methods in detecting the presence of NBC agents. The utilization of small robotic platforms equipped with NBC sensors is one way to aid in reconnaisance missions along with inspecting suspicious areas and vehicles. The U.S. Army's Omni-Directional Inspection System (ODIS) and iRobot's Packbot are two low profile robotic platforms that are being investigated by the U.S. Army TARDEC's Robotic Mobility Laboratory (TRML) to perform such tasks. There currently exists a variety of testing methods used in detecting NBC agents, which each have advantages and disadvantages. These different methods, along with their advantages and disadvantages are discussed in this paper. Traditional NBC type sensing systems are large requires a large vehicle or a trailer to be transported. To integrate these sensors into small robotic systems, they need to require less power and shrunk in size. Some commercially available products and ongoing research at government and academic laboratories are looking at improving NBC based detection systems are discussed in this paper for the integration of robotic platforms.