Glass micro-structuring by electrochemical discharges

随着芯片实验室和微器件制造需求的增加，玻璃在微技术领域具有重要意义。光学开关、电子电路的冷却元件和生物医学应用的微型混合器是需要玻璃微加工的少数几个例子。对于这些应用，玻璃需要具有特定的特性。因此，对能够加工具有特定表面特性的玻璃的技术的需求已成为必要。我们对电化学放电(ECD)在玻璃微加工(火花辅助化学雕刻；SACE)中的应用进行了研究，使这项技术达到了一定程度的成熟，在不久的将来为微流控芯片中的通孔钻孔带来了商业化。但SACE(精密度、重复性、提高材料去除效率)的优化工作仍需进行。过程控制算法仍然缺失。成功地解决这些问题将使SACE能够进入需要非常高精度的微钻孔的应用领域，例如微喷嘴的制造。为了进一步开放SACE的应用领域，必须更好地挖掘ECD的潜力。ECD不仅携带热量(用于促进局部玻璃刻蚀)，还携带电子。因此，可以利用在这些放电附近发生的局部电化学反应。这一想法被我们用来开发了一条利用ECD合成纳米颗粒的路线。合乎逻辑的下一步是将这两个领域的知识结合起来，以开发一种新的工艺，通过在玻璃中掺杂金属纳米团簇来局部改变玻璃的性质(如玻璃表面的颜色、纹理、机械强度)。ECD对玻璃的局部改性将为SACE在微流控、生物医疗或光学设备的微制造中开辟新的应用领域。 所有这些开发都旨在将SACE转变为一种高通用性和精确度的微加工工艺，用于成本效益高的玻璃微器件快速成型。

Glass gains significance in the micro technology field with the boost in the demand of lab-on-a-chip and micro devices fabrication. Optical switches, cooling elements for electronics circuits and micro-mixers for biomedical applications are few examples demanding glass micro-machining. For these applications, glass is required to have specific properties. Hence, the need for technologies able to machine glass, with specific surface properties, has become a necessity. Our study of the application of electrochemical discharges (ECD) to glass micro-machining (Spark Assisted Chemical Engraving; SACE) allowed reaching a degree of maturity of this technology bringing commercialisation in a very near future for vias drillings in micro-fluidic chips. But work on the optimisation of SACE (precision, repeatability, enhance material removal rate) is still needed. Process control algorithms are still missing. Addressing successfully these issues will allow SACE to enter applications requiring very high precision micro-drilling, such a micro-nozzle fabrication. To further open fields of applications to SACE, the potential of ECD have to be exploited better. ECD do not only carry heat (used to promote local glass etching), but electrons as well. It is therefore possible to take advantage of localised electrochemical reactions occurring in the vicinity of these discharges. This idea was exploited by us in developing a route for nanoparticle synthesis by ECD. The logical next step is to combine the knowledge of both fields in order to develop a new process to modify locally glass properties (e.g. color, texture, mechanical strength of the glass surface) by doping glass with metal nano-clusters. Local glass modification by ECD will open new applications for SACE for the micro-fabrication of micro-fluidic, bio-medical or optical devices. All these developments aim to turn SACE into a highly versatile and precise micro-machining process for cost effective rapid prototyping of glass micro-devices.