I am working on a project where I need to log data, but I was wondering if it is possible to log that data to a thumb drive? I know that I can log data to an SD card, but I thought a thumb drive would be more accessible to users who wish to obtain the data. And if it is possible to log to a thumb drive, could it be done in CSV format? The data is just sensor data.
In principle you can log to a thumb drive any data you want, binary and text (thus also CSV).
However, the Arduino Uno does not support connecting a USB stick directly. If you want to connect a USB stick, you need a so called USB Host shield (for Arduino).
More information can be read on the Arduino site at this page:
As an alternative to a Uno host shield, changing to a different Arduino MCU may also assist. USB host capabilty is needed for communicating with thumb drives.
Some Arduino models have a native USB port (e.g., Arduino Due, Arduino Leonardo, Arduino Micro, Arduino Nano 33 IOT, Arduino Zero, Arduino MKR Zero, Arduino MKR1000 ... ) which will work as a USB client device role.
A smaller set of MCU can act as either a USB client or host (e.g., Arduino Due, Arduino Portenta, ...). There is a USBHost library for Arduino Due listed in the Arduino Reference. Documentation for Arduino Portenta in USB host mode is here.
Here is a discussion (and reference to an alternative library) regarding using a Due to write files to a thumb drive.
Of course an adapter cable or a thumb drive with a physical connector matching the native USB port on the selected MCU is required. Both are commonly available.