Kim Lau

Digital imaging as a detector for quantitative colorimetric analyses

In this paper, a digital imaging system was used to analyze a series of colorimetric reagent dots. A commercially available digital camera was used with in-house developed software to capture and analyze data. The color captured was digitized and broken down into three 8-bit color values (red, green and blue). The data was then processed to generate distinct recognizable patterns that represent the original color input. A pH indicator sensor array was used to demonstrate the practicality of the system. Preliminary results show that the system is able to discriminate samples over a wide pH range (pH 1-13) and resolve samples to within ± 0.5 pH units.

A sleep bruxism detection system based on sensors in a splint – pilot clinical data

It is difficult in a dental setting to accurately diagnose sleep bruxism and to objectively assess the severity, frequency or natural history of the condition in an individual patient. Yet this information is essential for the management of sleep bruxism and to plan appropriate dental treatment. The objective of this study was to clinically test a device that could be used to record bruxism events in a home environment. Pressure sensors were developed for use under the surface of an occlusal splint, and circuitry was designed to facilitate the recording and wireless transmission of the pressure sensor signal to a computer. Controlled mandibular movements were carried out in vivo to simulate bruxism and non-bruxism patterns. These patterns of force application were graphically presented to two examiners who were asked to identify the type of activity represented by the force curves. Examiners were largely able to distinguish bruxism from non-bruxism activity; the sensitivity ranged from 80% to 100% and the specificity from 75% to 100%. Using sensors in an occlusal splint, it is possible to recognise the typical tooth contact patterns seen in sleep bruxism. Such a device may be useful for monitoring sleep bruxism over an extended period at home.

Web-based colorimetric sensing for food quality monitoring

The work presented in this paper outlines a novel technique for remote food quality control over the Internet by using web based image processing. The colour change of a colorimetric sensor was captured with a wireless camera and the data was transmitted to a PC, which uploaded the information to the web. A software system for colour analysis was developed to process the data locally. Quantitative colour information which reflects the quality of the food product can be deduced remotely using this technique. This novel technique was applied to the monitoring of fish spoilage in packaged fish. The on-package sensors detected the release of spoilage products, typically the amines, from the fish and gave a visible colour change which was captured by the wireless camera. The colour information obtained through the web, when processed remotely using the in-house developed software, accurately reflected the state of the product. This technology reduces the labour requirements in food quality monitoring and can be applied to all colorimetric sensors.