Flexible and Biofouling Independent Salinity Sensor

Abstract

Salinity is one of the most relevant parameters in oceanography used to study properties of the oceans as well as the effects of climate change. Salinity measurements are challenging, due to the harsh environment that leads to corrosion and biofouling. In the context of animal monitors, salinity sensors should also be minimally intrusive and have a long lifetime. Here, a conductivity cell for salinity sensing is presented based on a single-step laser irradiation process on flexible polyimide substrate. The sensors are characterized by lightweight, flexibility, low power consumption and low fabrication costs. A two-electrode cell is used to measure the impedance, and thereby the conductivity, of the water in the MHz frequency range. It offers an accuracy of ±0.5 psu, which is not affected by sensor deformation.Deployment of the sensors in the Red Sea revealed that the materials are corrosion resistant and can withstand the harsh environment. While biofouling is strongly affecting commonly employed low frequency conductivity measurements, in the MHz frequency range, it acts like a short-circuited capacitance. Hence, biofouling independent salinity sensing can be achieved using a two-electrode impedance measurement at a frequency of 1 MHz.Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff)) Published online: ((will be filled in by the editorial staff))

Laser‐Printed, Flexible Graphene Pressure Sensors

“…LIG sensors have both a high resistance to corrosion and an operating temperature range of up to ≈400 °C. [ 16,20 ] Figure shows the response recorded from an LIG tactile sensor (structure as shown in Figure 2a) in response to being pushed with the index finger by a touch, softly pressed, and hard pressed. The output increased immediately at the moment of contact of the index finger and returned to the initial values after release.…”

“…[1][2][3] Extensive research has been undertaken to obtain robust pressure sensors for this so-called laser-induced graphene (LIG) has been utilized to create numerous electronic devices in a single step. [16][17][18][19][20] In the present study, we demonstrate the use of LIG to fabricate piezoresistive, mechanically flexible, lightweight, and robust pressure sensors with a large measurement range, thereby offering promise across the whole spectrum of demands for pressure sensors.…”

Wearable multifunctional printed graphene sensors

“…20,27 The high variation of the electrical resistance of multilayer samples under strain was explained by the displacement of the layers and changing their overlapping area, which provides the ability to use these structures for force and strain sensors. 20 In 2014, it was discovered that direct lasing of PI films leads to the formation of 3D porous graphene, [32][33][34] by a photothermal process associated with a localized high temperature, the pressure produced by laser irradiation and easy absorption of longwavelength radiation. This process enables the development of LIG bending sensors that are mechanically flexible, lightweight, robust, and multifunctional.…”

Animal-Borne Telemetry: An Integral Component of the Ocean Observing Toolkit

“…Revolutions in sensor technology are also being translated into a new generation of sensors to track marine life, with significantly reduced footprints and power requirements, including the capacity to harvest power from the environment, better accommodating animal anatomy and movement and containing significantly enhanced capacities for data storage and analysis. Examples of these revolutionary sensors include the "marine skin," a flexible-stretchable silicon-printed sensor system that brings the concept of wearable to marine animal tags (Nassar et al, 2018), new magnetic sensors to monitor animal behaviors in detail (Kaidarova et al, 2018a), and graphene-based flexible, ultrathin, and light salinity sensors to acquire oceanographic information (Kaidarova et al, 2018b).…”