Quantitative Process Control Research Articles

Interlocking design, programmable laser manufacturing and testing for architectured ceramics

Tough and impact-resistant ceramic systems offer a wide range of remarkable opportunities beyond those offered by the conventional brittle ceramics. However, despite their promise, the availability of traditional manufacturing technique for fabricating such advanced ceramic structures in a highly controllable and scalable manner poses a significant manufacturing bottleneck. In this study, a precise and programmable laser manufacturing system was used to manufacture topologically interlocking ceramics. This manufacturing strategy offers feasible mechanisms for a precise material architecture and quantitative process control, particularly when scalability is considered. An optimized material removal method that approaches near-net shaping was employed to fabricate topologically interlocking ceramic systems (load-carrying assemblies of building blocks interacting by contact and friction) with different architectures (i.e., interlocking angles and building block sizes) subjected to low-velocity impact conditions. These impacts were evaluated using 3D digital image correlation. The optimal interlocked ceramics exhibited a higher deformation (up to 310%) than the other interlocked ones advantageous for flexible protections. Their performance was tuned by controlling the interlocking angle and block size, adjusting the frictional sliding, and minimizing damage to the building blocks. In addition, the developed subtractive manufacturing technique leads to the fabrication of tough, impact-resistant, damage-tolerant ceramic systems with excellent versatility and scalability.

Direct Laser Writing-Based Programmable Transfer Printing via Bioinspired Shape Memory Reversible Adhesive.

Flexible and stretchable electronics offer a wide range of unprecedented opportunities beyond conventional rigid electronics. Despite their vast promise, a significant bottleneck lies in the availability of a transfer printing technique to manufacture such devices in a highly controllable and scalable manner. Current technologies usually rely on manual stick-and-place and do not offer feasible mechanisms for precise and quantitative process control, especially when scalability is taken into account. Here, we demonstrate a spatioselective and programmable transfer strategy to print electronic microelements onto a soft substrate. The method takes advantage of automated direct laser writing to trigger localized heating of a micropatterned shape memory polymer adhesive stamp, allowing highly controlled and spatioselective switching of the interfacial adhesion. This, coupled to the proper tuning of the stamp properties, enables printing with perfect yield. The wide range adhesion switchability further allows printing of hybrid electronic elements, which is otherwise challenging given the complex interfacial manipulation involved. Our temperature-controlled transfer printing technique shows its critical importance and obvious advantages in the potential scale-up of device manufacturing. Our strategy opens a route to manufacturing flexible electronics with exceptional versatility and potential scalability.

Application of an electronic nose to the discrimination of coffees

An investigation has been carried out into the response of an array of twelve tin oxide sensors to the headspace of coffee packs. Discriminant and classification function analyses are performed on the array response to each of three commercial coffees (covering two different blends and two roasts) as well as one coffee which has been subjected to a range of six roasting times. Multivariate functions are calculated from the entire data set (90 samples) or alternatively using half of it, to permit cross-validation. A success rate of 89.9% is achieved with the former procedure in classifying the three commercial coffee odours directly from the response (change in sensor conductances) of the array. This value falls to 81.1% when half of the data set is used for cross-validation. Preprocessing the array data, by normalizing the response of each sensor over the array, is found to increase the success rate (to 95.5%) on the entire data set only. The effect on coffee odour of a set of six roasting times (zero to 11.5 min) is also investigated and found to be considerable, some sensors registering an increase in conductance by a factor of three. A 100% group classification is achieved with zero and long roasting times, the overall success rate being 88.1%. The main conclusion is that tin oxide gas sensors can be used to discriminate between both the blend and roasting level of coffee, confirming their potential application in an electronic instrument for on-line quantitative process control in the food industry.