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© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Engineering of highly performing nanomaterials, capable of rapid detection of trace concentrations of gas molecules at room temperature, is key to the development of the next generation of miniaturized chemical sensors. Here, a highly performing nanoheterojunctions layout is presented for the rapid room-temperature chemical sensing of volatile organic compounds down to ten particles per billion concentrations. The layout consists of a 3D network of nickel oxide–zinc oxide (NiO–ZnO) p–n semiconductors with grain size of ≈20 nm nanometers and a porosity of ≈98%. Notably, it is observed that the formation of the p–n heterojunctions by decoration of a ZnO nanoparticle networks with NiO increases the sensor response by more than four times while improving the lower limit of detection. Under solar light irradiation, the optimal NiO–ZnO nanoheterojunction networks demonstrate a strong and selective room-temperature response to two important volatile organic compounds utilized for breath analysis, namely acetone and ethanol. Furthermore, these NiO–ZnO nanoheterojunctions show an inverse response to acetone from that observed for all others reducing gas molecules (i.e., ethanol, propane, and ethylbenzene). It is believed that these novel insights of the optoelectrochemical properties of ultraporous nanoheterojunction networks provide guidelines for the future design of low-power solid-state chemical sensors.

PurposeSome population groups face precarious health, reflecting their vulnerability, in terms of lack of agency or control. Smart technologies promise to transform people's lives from the enhanced connectedness, greater computational processing and more complex decision-making they can achieve. This study aims to investigate how smart technology can mitigate vulnerability and improve well-being.Design/methodology/approachThe research group, of three scholars and three managers, pursued an action research methodology with an iterative process of planning, action and learning. The authors conducted three related action studies: (1) adopting smart technologies, (2) fostering patient engagement and (3) assessing well-being.FindingsThe adoption of sensors and wearable devices had positive impacts for both patients and caregivers. Technologies highlighted their meaning as resources to support actors' (caregivers' and vulnerable patients') activities. Smart devices as resources get integrated, stimulate change and enable new practices. For caregivers, such innovative solutions help improve their knowledge of patients and their ability to act efficiently; for vulnerable patients, they fostered engagement in daily activities to improve well-being.Originality/valueThe paper delineates an overall model (SEVP) that describes how the integration of high-tech and high touch enables patient engagement to mitigate vulnerability and improve well-being.