The diagnosis of oral potentially malignant disorders currently relies on histopathological examination of surgically removed biopsies causing pain and discomfort for the patient. We hypothesise that non-invasive bioimpedance spectroscopy (BIS) method would overcome these problems and could make possible regular screening of at-risk patients. Previously several handmade probes have been introduced in such BIS studies. However, for the first time, we aimed to design a 3D printed probe and test it with model samples (saline solutions, cucumber and porcine tongue). We found that it is extremely crucial to select proper printable materials and optimise electrode geometries to avoid electrochemical corrosion problems, short-circuiting and other signal instabilities related to miniaturised probe. However, our final prototype constructed with four high purity silver made electrodes showed a good linearity (R 2 ¼ 0.999) in diluted saline solution measurements over a wide conductivity range (0.25-8 mS/cm), which covers well the range of values for the different biological tissues. Moreover, our data show that high reproducibility of the manufacturing and measurement is one important merit in the present 3D printed probe. However, further studies are needed to clarify the importance of fixed pressure especially when the tetrapolar 3D printed probe is used as a hand-held apparatus.

Wood–plastic composites (WPCs) have numerous indoor applications, including framing, decoration and flooring. However, the impact of WPCs on indoor air quality has not been widely studied. Proton-transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) was utilized to monitor the release of volatile organic compounds (VOCs) from a commercial WPC for 41 days since its day of manufacture. Additionally, the emission rates of VOCs from seven different WPC samples were compared and converted into air concentrations to evaluate whether the odour thresholds would be exceeded. The VOCs studied were formaldehyde, acetaldehyde, acetic acid, cyclohexene, furan, furfural, guaiacol and monoterpenes. The results from the 41-day test revealed that the emission rates of monoterpenes, guaiacol, furfural and acetaldehyde declined by 75%–93%, whereas an opposite phenomenon was observed for cyclohexene (nearly a threefold increase). The comparison of VOC emission rates from seven WPC samples indicated that none of the samples had the lowest or highest emission rate for every VOC studied. The present results are significant in at least two aspects; this study shows that the VOC emission rates from WPCs can be determined by using PTR-TOF-MS. Furthermore, it seems that guaiacol and acetaldehyde exceed their odour thresholds and therefore humans will be able to detect these compounds from the WPCs studied.

A novel modular tank layout, which flexibly adapts to various electroplating processes, is introduced and its feasibility has been studied by a three-dimensional simulation model. The new layout uses floor space and process volume more effectively and brings necessary novelty to the electroplating industry which partially suffers from outdated process equipment and low competitiveness. Trivalent chromium plating has been chosen as a test process in the simulation model since replacing hexavalent chromium is an important issue in the industry. The simulation model has been verified by conducting an extensive series of experimental coating thickness measurements and supplementing the model with these results. The results of the simulations support the feasibility of the new tank layout and show that it is possible to obtain good coating thickness uniformity when running separate coating processes simultaneously in one tank with different plating currents and surface areas of the objects to be plated.

No abstract

Three-dimensional (3D) printing has a high potential in various biomedical applications. We hypothesise that 3D printing could be a viable option to construct bioimpedance spectroscopic (BIS) sensors suitable for electrochemical characterization of oral mucosal tissues. Previous BIS studies have been relied on hand-made probes possessing significant limitations related to single patient disposable use, great inter-probe differences and weak reproducibility of measurement. There is also uncertainty related to effect of varying loading pressure between the probe and biological tissue. Here, we introduced three different sized rectangular shaped 3D printed probes and test those using four-terminal measurement principle on various porcine oral tissue samples. We found that constructing fully 3D printed probe is a challenging task and prone to issues relating to short circuiting or electrochemical corrosion. However, our final protype version constructed with silver-coated copper electrodes showed favourable characteristics in BIS experiments. All three different sized probes were able to differentiate between different tissue types with excellent reproducibility. The effect of loading pressure was found to be almost negligible when using small and medium sized probes. However, further studies are needed to measure tissues with uneven surfaces, such as palatinum, and to avoid manual or electrochemical surface finishing steps.