We're pleased to introduce a newly developed temperature string built specifically for SIMB3. The SIMB3 Embedded Temperature String was designed to be significantly more resilient than our past strings while maintaining scientific compatibility with previous datasets.
Quick Highlights
- A rigid two-part (non-flexing) design that is permanently bonded to the exterior of the hull.
- Full 12-bit precision (0.0625 deg C) for each temperature. Our Bruncin strings had 0.125 deg C resolution.
- 160 temperature sensors spaced at 2 cm through the ice, ocean, and atmosphere (to maintain compatibility with Bruncin strings).
- A tool-free, contactless deployment. You never need to interact with the string at any point when handling or deploying SIMB3.
Motivation
Temperature strings are tricky. They are expensive, delicate, and fully exposed to the harsh Arctic environment that SIMB3s operate in. We wanted to see if we could improve upon the past designs that we have used by creating a string custom made for SIMB3.
More specifically, we wanted to make a string that was really, really, tough. We think we did it.
Design
Physical
The new SIMB3 Embedded Temperature String is actually two strings. It is a two-part design, with one half bonded to the upper section of SIMB3 and the other half bonded to the lower section. The two halves meet in the middle and maintain a constant, even 2 cm spacing of sensors.
By splitting the string, we avoided it needing to be flexible while still maintaining the ability for the SIMB3 to fold in half.
The string PCBs are rigid and soldered together to form a continuous length of sensors. The soldered PCBs are then inserted into a custom plastic saddle and potted with low thermal-conductivity potting compound. Just enough potting compound is used to cover the sensors and insulate them electrically.
Electrical
The string uses a cousin of the ubiquitous DS18B20 temperature chip, the DS28EA00. The DS28EA00 is hardware chainable, however, allowing the chips to discover their physical location in the chain automatically. They also use the Maxim One-Wire protocol for communication, making the whole system operate with just three conductors.
By reducing the number of conductors, we improve the resilience of the string by reducing the number of failure points.
Conclusion
All SIMB3s shipping in 2023 and beyond will have the Embedded Temperature String, and several of these have already been deployed. The designation for instruments with the Embedded Temperature String is SIMB3 V4.