Spark assisted chemical engraving (SACE), an innovative technology for glass micromachining

Glass is a fantastic material for a medical device. It is biocompatible, chemically inert, straightforward sterilisable and optically transparent, but machining is also a challenge.<br>Spark Assisted Chemical Engraving (SACE) is a hybrid technology based on thermally assisted chemical etching of glass. Discovered by Kurafuji and Suda in 1968 [1], this process now emerges at the industrial level as a flexible, rapid and cost-effective possibility to machine the glass.<br>This novel technology machines the glass without burrs, cracks or deposits on the surface.<br>A pulsed potential [2] is applied between the tool and a counter-electrode into a conductive electrolyte, typically NaOH. Sparks appear at the tool, which allows increasing the temperature of electrolyte locally around the tool. The electrolyte, when heated, becomes highly corrosive for glass, which is ?electro-dissolved? locally.<br>This process coupled to a highly accurate Computer Numerical Control (CNC) machine allows drilling micro-holes with a depth of millimetres in a few seconds and mills channels of several hundred microns deep without difficulty. With this equipment, it is also possible to cut the glass over a thickness of a few millimetres or create a chamfer, for example. All these machining methods can be realized directly, without any intermediate process. <br>After presenting the SACE process and technology, some applications in medical and microfluidic areas will be demonstrated.