Abstract
Fruit growth is a complex process influenced by various biochemical and biophysical mechanisms, environmental factors, as well as management practices. The growth of various fruit species has been studied extensively, especially in terms of fruit diameter, as this is as a key parameter for analysis. Various methods, including transducer sensors, strain gauges, and linear potentiometers, have been proposed for continuous fruit growth monitoring. However, fruit growers have been slow to adopt these instruments, possibly due to the lack of user-friendliness, the high costs associated with the use of these techniques in measuring campaigns, as well as the maintenance required. Here, taking advantage of the progress that the field of flexible and stretchable electronics has recently experienced, we propose a novel, minimally invasive, and stretchable resistive strain sensor as an alternative to address this challenge. The sensor works by varying its electrical resistance in response to mechanical deformation. The initial design will feature a serpentine layout made of stretchable conductive ink, along with silicone rubber encapsulation. The silicone rubber will encase the serpentine layout within a sandwich structure created through successive layer coating. To identify the optimal combination that meets all requirements and constraints, a thorough material investigation will be conducted. This innovative strain sensor offers potential for adoption in continuous monitoring of fruit growth. It is affordable and requires little to no maintenance once installed. This paves the way towards real-time data acquisition on fruit growth, enabling timely advice for decisions on irrigation management, fruit thinning, and harvest predictions.