FieldKit Underwater

The technology that dominates the field of underwater sensing tends to cost multiple thousands of dollars, creating a large barrier to entry for many who need data on underwater conditions over long periods of time at high frequencies. The low-cost FieldKit Underwater is a prototype for an open source alternative.

Description
pH
Conductivity
Dissolved Oxygen
Pressure and Temperature

The FieldKit Underwater platform is intended to be a multi-parameter datalogging sonde for fully submerged use for long deployments on the order of months. The design of the prototype unit enables the use of multiple rechargeable lithium ion battery packs and high-capacity µSD cards for extended deployment periods. The unit is designed to gather data from multiple sensors, and includes circuits to interface with probes for dissolved oxygen, pH, electrical conductivity, external temperature, and oxidation reduction potential on-board. Also included is a pressure and temperature sensor. The prototype also includes a vent port for pressure testing the enclosure.

Powered by a ATSAMD51 series 32-bit low-power microcontroller
Includes probes and sensors for pH, electrical conductivity, dissolved oxygen, pressure, and temperature
Temperature-compensated high precision RTC
Onboard data logging to built-in flash memory
Rugged design supports long-term field deployment
Capable of running weeks unattended on battery power with optimized sensor modules

pH	0.001 to 14.000 (±0.002)
Probe Diameter	12 mm
Temperature Range	0-99 °C
Cable Length	1 m
Interface	SMA connector on 50 Ω coaxial cable
Calibration Period	6 months
Panel Footprint	1 SMA connector
Bulkhead Plate Footprint	1 ¾” NPT probe gland
Current Consumption	16 mA

Electrical Conductivity	0 to 500000 (±10000) µS/cm
Probe Diameter	12 mm
Temperature Range	1-60 °C
Cable Length	2 m
Interface	SMA connector on 50 Ω coaxial cable
Calibration Period	6 months
Panel Footprint	1 SMA connector
Bulkhead Plate Footprint	1 ¾” NPT probe gland
Current Consumption	30 mA

Dissolved Oxygen	0.01 to 100 (±0.05) %O2
Probe Diameter	16.4 mm
Temperature Range	1-60 °C
Cable Length	2 m
Interface	SMA connector on 50 Ω coaxial cable
Calibration Period	6 months
Panel Footprint	1 SMA connector
Bulkhead Plate Footprint	1 ¾” NPT probe gland
Current Consumption	16 mA

Pressure	0.01-2.00 (±0.05) bar
Temperature	2.0-40.0 (±0.1) °C
Probe Diameter	16 mm
Temperature Range	-20-85 °C
Cable Length	45 cm
Interface	4-pos JST GH connector on 4 24 AWG conductors (I2C @ 3.3 V)
Calibration Period	1 year
Panel Footprint	1 4-pos JST GH connector
Bulkhead Plate Footprint	1 M10 through hole
Current Consumption	1.5 mA