Chromatographic and sensor-based analysis of skin volatile emissions

Non-invasive techniques for skin analysis including wearable sensor are continuously being explored for their use in personalised healthcare to track movement, blood pressure and heart rate among many other parameters. Recently, focus has shifted towards the development of such wearable sensors for use in biochemical analysis. Accurately diagnosing or predicting the course of an epidermal disease in an individual is challenging due to the complex nature of the skin. Epidermal sensors are a subclass of wearable sensors that are designed to have intimate contact with the skin and are used to monitor physical changes in the skin barrier and detect skin disease biomarkers that can be related to human health. Challenges associated with epidermal sensors is the difficulty of sampling from the skin and also tuning the sensor for the selective detection of a target biomarker or set of biomarkers. The overall aim of this thesis is to investigate the skin volatile emission profile as a potential matrix for analysis and to obtain bio-diagnostic information related to skin health. Chapter 1 of the thesis reviews the literature related to skin structure, function and the methods used for non-invasive skin surface assessment. Chapter 2 explore the potential of using skin volatile samples collected via solid phase micro extraction in a wearable format as a means to assess skin surface pH. Chapter 3 describes the synthesis of a novel dye and the development of dye into a wearable colorimetric skin sensor for the detection of skin emitted volatiles. Although, this sensor is at its early stages of development it has demonstrated selectivity towards skin volatile amines. The work done highlights the possibility of using skin volatiles as a means of assessing skin properties whereby, the measurement of skin surface pH based on the volatile emissions was demonstrated using a wearable colorimetric sensor. Since, skin pH is an important property to monitor for optimal skin barrier function and cutaneous antimicrobial defence, it is envisaged that this sensor could be deployed for health monitoring in the future