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From Ideation to Commercial Application
From Ideation to Commercial Application
What began as a idea for an applied R&D project combining marine telemetry and sensing has been advanced to a pre-commercial state with testing currently ongoing in the world's seas!
Research and Development Goals
Research and Development Goals
The design of wearable, noninvasive, bio-electronic sensors for marine environments is a critical next step in Internet of Everything applications. Current technologies are rigid, bulky and expensive making difficult the process of deployment and data acquisition. The characterization of waterproofed marine sensors designed to monitor animal and ecological health in a noninvasive reliable manner that couples sensing with existing telemetry systems is essential.
Current telemetry and sensing equipment is neither robust enough or conformal enough to provide information on the environment, nor able to adaptively reconfigure to the free-form flexible dynamic surfaces of the animals to which it is attached. Addressing this while combining telemetry and sensory systems is imperative.
Initial sensor design
Initial sensor design
A serpentine electrode path was initially fabricated for a Resistive Temperature Detector (RTD), which maximizes the area for thermal exposure thereby providing the most perceivable change in resistance. A networked array of such sensors offered small volume and high accuracy due to ease of resistive measurement with incredibly short relative response time because of proximity of thermal contact, limited by the thickness of the encapsulating materials. This can be described as: RT = R0 * (1 + αT * T) where α is the temperature coefficient of resistance.
Pressure scales linearly with changes in depth, which allows a sensor to be fabricated using capacitance. A parallel plate capacitor, with the encapsulating material acting as the dielectric, offers a compelling design opportunity. C * d = ε * A, where ε is the permittivity of the encapsulating materials and A is the cross-sectional area, and d is the encapsulation's thickness. The thickness decreases as pressure (an analog for depth) increases.
Multi-level resistive (temperature) and capacitive (pressure/depth) measurement
Multi-level resistive (temperature) and capacitive (pressure/depth) measurement
Serpentine/spring-like nerve network to allow out-of-plane stress deformations enabling flexibility
Hexagonal designs have good energy absorption, in-plane modulus, and low bending stiffness enabling flexibility
Gold sputtered negative mask layer two over polyimide interface and PDMS layer, preparing for final reactive ion etch, on-chip systems integration, and waterproofing.
Finalized net-like mask designs overlaid for resistive, capacitive, and salinity sensing.
Packaged devices
Packaged devices
Outset digital photo depicts the reconfigurable net-like array I design shown above. The net-like array offers geometric stretchability, flexibility, and a conformal fit. The system is waterproofed and continuously logs temperature, pressure, and salinity data from the surrounding environment, to assess ocean health and track animal mobility. Real-time data is then wirelessly transmitted upon resurfacing of the marine animal.
Nanofabrication process flow
Nanofabrication process flow
Process flow developed for flexible device. Approach is designed to be CMOS compatible, allowing ease of scalability, batch fabrication and precision. Steps (a–c) are prepared on a separate wafer 1, to make flexible 10 µm sheets of polyimide (PI). The multisensory system is fabricated on wafer 2, through steps (1–12), illustrating the integration of arrays of capacitive pressure sensors, resistive temperature detectors, and salinity sensing capability. Step (13) displays the conformal 3D system integration, followed by (14) a compliant encapsulation of the system, and (15) final system release.
Multi-sensory device performance under concave bending conditions
Multi-sensory device performance under concave bending conditions
(a) resistive response to water temperature variations;
(b) capacitive response to increased underwater pressures/depth;
(c) resistive response to salinity changes via KCl concentration increments;
(d) effect of temperature on the pressure sensor’s performance;
(e) dynamical resistance fluctuations obtained from different thermal conditions, where dash lines denote depth of immersions; and
(f) effect of depth of immersion on the temperature sensor’s performance
Commercial Developments: Bluefin™
Commercial Developments: Bluefin™
Bluefin™ is a pioneering wearable gadget to continuously monitor the oceanic environment (temperature, depth, salinity, and pH) down to a depth of 1.7 km for more than 6 months, as experimentally verified. It has a battery lifetime for 1 year, 36 cm2 is the maximum size and weighs 2.4 grams or less.
Coverage: Fish Wearing ‘Marine Skin’ Sensors Collect Information 6,500 Feet Below The Sea. Forbes Science, 5 March 2020.
CES 2020 Innovation Award Product: Bluefin
CES 2020 Innovation Award Product: Bluefin
Publications & Pending Patent
Publications & Pending Patent
Compliant lightweight non-invasive standalone “Marine Skin” tagging system.pdf
NPJ Flexible Electronics, © KAUST; US/EPO/WIPO Patent Pending
Note: published information and released material was created or collected by the author, and is used with permission. Image of RTD courtesy of "Sensor Fabrication Method for in Situ Temperature and Humidity Monitoring of Light Emitting Diodes", CY Lee et al., 2010. Sensors 2010, 10(4), 3363-3372; https://doi.org/10.3390/s100403363. Image of Parallel Plate Capacitor courtesy of Wikimedia Commons, Wikipedia, Wikimedia Foundation. Example image of telemetry equipment size courtesy of "Aquatic animal telemetry: A panoramic window into the underwater world", NE Hussey et al. June 2015. Journal of American Association for the Advancement of Science, Vol. 348, Issue 6240.
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