Storing cryogenic samples 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. I will specifically point out how and why Rust is the ideal language for this development and how it can be used across the hardware stack.

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. The electronics board 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.