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A novel high-pressure (water pump pressure up to 250 MPa) abrasive slurry micro-machining (HASJM) system was introduced. By feeding a premixed slurry into the mixing chamber of a water jet machine with a micro-nozzle (mixing tube diameter of 254 μm), premature erosion of system components was avoided. An optimum erosion rate of 2.7 mg/g was reached when machining Al6061-T6 with a slurry of 25 μm aluminum oxide particles under conditions (slurry flow rate=200 g/min and water pump pressure=235 MPa) near to those which theoretically maximized momentum transfer between the inlet slurry and the water jet entering the mixing chamber from the orifice. It was found that when the standoff distance increased tenfold, the erosion rate almost doubled in glass, but decreased by 50 % in Al6061-T6, due to differences in the erosion at the jet periphery for the two materials. For aspect ratios greater than 0.9, high-quality symmetric channels with a centerline waviness below 6.9 μm and a centerline roughness below 1.1 μm could be produced using a single pass at a low traverse velocity of 40 mm/min. The use of multiple machining passes at a relatively high traverse speed (~1000 mm/min) was found to produce asymmetric channels when the aspect ratio was greater than 0.9, owing to jet deflection from steps formed on the cutting front. Channels produced by micro-milling Al6061-T6 and glass had a 50 % lower centerline waviness and 16 % lower centerline roughness than those made with the conventional abrasive water jet in which air and abrasive entered the mixing chamber.

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Soft lithography techniques has been used widely in the past decade to fabricate microfluidic chips used in biomedical applications. Abrasive jet machining (AJM) has been used to fabricate similar chips using particle erosion mechanisms. This thesis proposes a new technique using a UV light sensitive self-adhesive mask (RapidMask) and AJM to fabricate a three dimensional flow focusing microfluidic chip where the depth of the channel is allowed to vary along the channel length. A detailed characterization of the effect of curing parameters of a UV light curing self-adhesive mask on the resulting feature resolution is reported. Instead of relying on the manufacturer recommended curing parameters which were vaguely described for specific UV curing units, it was found that measured energy density could be used to quantify a recommended cure that is independent of the curing unit. The best achievable pattern on borosilicate glass using RM and AJM was found and reported along with the erosion rates of uncured, cured RM during AJM. A new methodology was introduced to use multiple layers of the RM in order to increase the achievable feature aspect ratio. The results of the RM curing and multiple layer investigation were then used to fabricate a three dimensional flow focusing chip with a varying depth at the focusing junction. The chip was then sealed and tested to demonstrate its capabilities and potential in healthcare and biomedical applications. To the best knowledge of the author, this thesis is the first to report using a double layer RM to fabricate a microfluidic chip using AJM.

Soft lithography techniques has been used widely in the past decade to fabricate microfluidic chips used in biomedical applications. Abrasive jet machining (AJM) has been used to fabricate similar chips using particle erosion mechanisms. This thesis proposes a new technique using a UV light sensitive self-adhesive mask (RapidMask) and AJM to fabricate a three dimensional flow focusing microfluidic chip where the depth of the channel is allowed to vary along the channel length. A detailed characterization of the effect of curing parameters of a UV light curing self-adhesive mask on the resulting feature resolution is reported. Instead of relying on the manufacturer recommended curing parameters which were vaguely described for specific UV curing units, it was found that measured energy density could be used to quantify a recommended cure that is independent of the curing unit. The best achievable pattern on borosilicate glass using RM and AJM was found and reported along with the erosion rates of uncured, cured RM during AJM. A new methodology was introduced to use multiple layers of the RM in order to increase the achievable feature aspect ratio. The results of the RM curing and multiple layer investigation were then used to fabricate a three dimensional flow focusing chip with a varying depth at the focusing junction. The chip was then sealed and tested to demonstrate its capabilities and potential in healthcare and biomedical applications. To the best knowledge of the author, this thesis is the first to report using a double layer RM to fabricate a microfluidic chip using AJM.