Oxidizing cryogenic sample storage in ultra-high vacuum

To store frozen research sample after sample preparation and prior to analysis, a storage chamber that keeps them at 120 K temperature and in ultra-high vacuum (~1e-9 mbar) is required. In this talk I will discuss the development and integration of the control electronics, firmware, and host software with user-interface that now controls our home-built cryostorage solution.

Controlling the chamber requires (a) control of certain parts via digital I/O lines, (b) communication with several existing instruments via established protocols (e.g., via RS-232), (c) reading, updating, and displaying the current status of the chamber and attached instruments, and (d) interfacing with the user. Electronics for task (a) was designed in-house and uses a RaspberryPi Pico2 board as the controlling MCU. Firmware for this MCU was written in Rust using embassy. This firmware communicates with our Rust-based host software (which takes care of tasks (c) and (d)) using postcard and postcard-rpc. Finally, we also developed Rust crates to communicate with various instruments via RS-232, RS-485, and OPCUA. The host software and touch-driven user interface runs on a Seeedstudio ReTerminal DM, a RaspberryPi compute module 4 based Linux computer with a 10" touch screen. The user interface was developed using Slint.

In summary: Our brand-new cryostorage chamber is already Rusty all over.