N221-060 TITLE: Chip Scale Oceanographic Sensor

OUSD (R&E) MODERNIZATION PRIORITY: Microelectronics

TECHNOLOGY AREA(S): Sensors

OBJECTIVE: Create a chip scale oceanographic sensor that can be integrated onto a ship or unmanned underwater vehicle (UUV) hull to accurately measure ocean water chemistry in real-time.

DESCRIPTION: A new generation of measurement technology is developing new, ultra-compact, ultra-reliable, low-power sensors with accuracy linked by a known degree of error to U.S. standard measurements. Partnerships with industry are developing fabrication processes similar to existing microelectromechanical systems (MEMS) that will manufacture these sensors as a rugged and inexpensive device. These new developments offer a new opportunity for the submarine community to access and utilize environmental data on the outer hull of a submarine. At present, these sensors have not been ruggedized to reliably function in the harsh environments the external hull of a U.S. Navy submarine endures during its service life. This SBIR topic seeks a hull-mounted (i.e., external) chip scale sensor for in-situ monitoring of oceanographic chemical parameters.

To protect against corrosion, a ship�s Impressed Current Cathodic Protection (ICCP) distributes electrical energy between sections of the hull. The ICCP control system measures voltages using seawater silver/silver-chloride reference electrodes and adjusts the electrical potentials appropriately. Changes in seawater chemistry near the hull will change the electrical potentials, creating the need for a real-time oceanographic measurement input to the ICCP feedback control. The objective of creating a chip scale sensor should integrate the following threshold oceanographic chemical parameter measurements into a single device without causing interference on the reference electrodes:

• Temperature: 0-50 � 0.1 �C
• pH: 7-11 � 0.1
• Conductivity: 1-6 � 0.001 S/m
• Dissolved oxygen: 1-14.6 � 0.1 ppm [2]
• Sampling rate of at least one per minute (required)
• Additional chemical parameters of interest include: chloride (�0.1 mg/L), bromide (�0.1 mg/L), sodium (�0.1 mg/L), calcium (�0.1 mg/L), sulfate (�0.1 mg/L), and sulfide (�0.1 mg/L)

These sensors will modernize the ICCP system to provide real-time ambient oceanography measurements that correlate with noise on cathodic protection reference cells. This will enable minimum impressed current emissions while still maintaining cathodic protection of the hull. The Naval Research Lab (NRL) has started modifying the ICCP controller to accept these oceanographic inputs, and has historic studies documenting the correlations between the oceanographic chemical parameters and corrosion polarization curves.

It is essential that the sensors maintain these accuracies under environmental stresses experienced by underwater hulls. These conditions include: temperature 0-50 �C, hydrostatic pressure cycling from 0-10,000 kPa, grade B shock requirements from MIL-DTL-901E [Ref 1] without leakage when subjected to hydrostatic pressure, total suspended solids of 0-120 mg/L, fouling and biofouling over extended deployment periods. Chip scale sensors have been demonstrated for the identified parameters and proposals should identify the sensors that are envisioned for integration. The integrated sensor should fit in a space less than 10.0 cm x 7.5 cm x 5.0 cm, use less than 10 watts of power, meet the Navy�s goal of a 20-year lifetime, and utilize low-cost MEMS manufacturing methods. Smaller sensors that meet these requirements will leave space for additional future sensors.

PHASE I: Develop a concept for an integrated sensor that achieves the needed measurement accuracy under temperature and pressure cycling presented in the Description. Determine the feasibility of the concept to meet the described parameters listed in the Description through modeling, simulation, and analysis. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.

PHASE II: Develop and deliver two prototypes of a chip scale sensors. Modify the sensors as needed and integrate the sensor package into a shipboard ICCP reference electrode holder. Demonstrate the prototype�s performance under the necessary environmental stresses: one month in a natural seawater environment where biofouling colonization is prevalent, such as Port Canaveral, FL. Certification of the natural seawater test environment will be conducted by the Naval Research Laboratory and Naval Surface Warfare Center, but the testing and evaluation will be conducted by the performer. Required hydrostatic pressure cycle evaluation will be conducted under laboratory conditions at the Naval Research Laboratory using a seawater pressure chamber. Documentation of all Phase II testing results should include independent parameter measurements documenting required accuracy. Identify the largest costs in manufacturing the sensor and assess cost reduction measures.

Deliver, for the environmental exposure demonstration, two packaged sensors for Navy evaluation.

PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to Navy use through system integration and qualification testing. Integrate the sensor package into the shipboard ICCP architecture and data acquisition system as part of a Temporary Alteration (TEMPALT). Demonstrate environmental exposure operation of the sensor package for a minimum of two years. Implement cost reduction measures and install sensors aboard a ship at multiple reference electrode locations. Mortality analysis and documentation of any failed elements will be required. This sensor can provide a low Size, Weight, Power and Cost (SWAP-C) replacement for existing oceanographic sensors, which are routinely used for oceanographic surveys or environmental ocean monitoring. Reassess and document the largest costs in manufacturing the sensor as well as cost reduction mitigations.

REFERENCES:

1. "MIL-DTL-901E, DETAIL SPECIFICATION: SHOCK TESTS, H.I. (HIGH-IMPACT) SHIPBOARD MACHINERY, EQUIPMENT, AND SYSTEMS, REQUIREMENTS FOR (20-JUN-2017) [SUPERSEDING MIL-S-901D]." http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-901E_55988/.
2. NIST on a Chip, https://www.nist.gov/noac/introduction.
3. Wei, Yaoguang et al. "Review of Dissolved Oxygen Detection Technology: from Laboratory Analysis to Online Intelligent Detection." Sensors (Basel), Sep 2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6767127/.
4. National Oceanography Centre, Southampton, UK, https://www.noc.ac.uk/technology/technology-development/instruments-sensors.

KEYWORDS: Oceanographic chemical analysis; Microelectromechanical Systems; MEMS; Impressed Current Cathodic Protection; Corrosion Protection; Measurement-science sensor; Underwater Electromagnetic Signatures