An open microfluidic design for contact angle measurement

Spontaneous capillary flow in open microchannels is a phenomenon driven by surface energies. The contact angle that the liquid forms with the channel's substrate material and the cross-section of the microchannel decide whether liquid from a connected reservoir will automatically fill the channel or not. In this work we show how this behavior can be used to design a passive contact angle measurement device (CAMD) based on parabolic open microgrooves. To that end, we present a theory of open capillary flow in such microgrooves and compare the results to minimal energy surface simulations. Additionally, we discuss that the condition for capillary flow of curved microchannels is essentially equal to the condition for their straight counterparts having the same cross-section.Lastly, we present two demonstrators of our CAMD made out of micromilled poly(methyl methacrylate). The devices consist of five open microchannels with different cross-sections which are connected to a common liquid reservoir. We show how the behavior of a liquid placed into that reservoir can be used to evaluate the contact angle between the liquid and the substrate material. A comparison to conventional contact angle goniometry shows that our approach is able to successfully estimate contact angles with an accuracy of 10° by design which can be improved by employing a greater number of microchannels. Since our devices were automatically designed and can be tuned to specific applications, this provides an easy approach to include contact angle measurement into existing lab-on-a-chip devices

Near Net Shape Manufacturing of Dental Implants Using Additive Processes

Dental implantation was introduced as a restorative procedure to reinstate the teeth functions and put the patient in normal contour, comfort, speech and health. Dental implants have been used over the centuries and the production techniques have been developed over the years. One of the advanced technologies is additive manufacturing (AM) which enables high degree of freedom ability to produce complex shaped and customized parts similar to human teeth. AM facilitates the production of complex geometric structure without the need of preparing expensive tools, hence it is more cost effective and time saving process. The current chapter provides an overview of AM as a promising technology for near net shape production of dental in preparing customised dental implants. The chapter also explore the anatomy and mechanical properties of human teeth together with the requirements for the design of teeth implants. The chapter survey the current AM technologies used for dental implant, clinical implications and highlights the future trend of AM in the development of near net shaped dental implants