In this graduation project for the start-up Dispertech, the usability and workflow of their NanoCET device is improved. The NanoCET is a research tool used in hospital and university laboratories, for which the following problem was stated: researchers and technicians working in labs have difficulty setting up and using the NanoCET device and software when conducting a measurement on the size distribution and concentration of nanoparticles. This leads to failed measurements and therefore a waste of time, materials, and samples. As a result of these issues, it is difficult for researchers to trust Dispertech and their NanoCET. The NanoCET faced challenges with its workflow, which is disrupted by going back and forth between the software and the device, with its underdeveloped analysis and measurement software, and missing feedforward and feedback in physical configuration elements like the ‘arena’, the clamp, and the cartridge. These usage issues have been traced during interviews and observations in the context, a competitor analysis, a functional analysis, a usability inspection, and a streamlined walkthrough. The final design is developed through explorative prototyping, associative sketching using methods like SCAMPER and morphological charts, and creative sessions with peer students and with Dispertech. The final design is focused on a guided and efficient workflow, facilitated by the device but mainly by the measurement software. (Inter)actions in the workflow of the final design are clustered as well as the process allows. Consequently, the workflow is split up into three phases: 1) Insert cartridge, 2) Prepare device, and 3) Measurement. The physical device shows multiple differences compared to the current NanoCET: the ON/OFF button is visible and easily reachable at the front, the finger indentation of the knob is coloured to emphasize this use cue, there are use cues for (opening) the clamp and the packaging of a cartridge facilitates carrying information. The cartridge itself is redesigned to protect the coverslip and to provide more feedforward and feedback by making use of colours (and shapes) resembling the corresponding phase. The ‘arena’ is designed to provide use cues and fit the new cartridge. Moreover, the LEDs on the physical device are placed so they are always visible, whether the interaction is performed seated, or standing up. Each LED has a different colour to track the three phases and their colours in the software. In the software, the user sees an overview of the whole process. Information is hierarchically layered, using hover-information buttons to provide extra input when it is required during the process. The least amount of input is required to set up a measurement, supported by automatically filling fields based on the information given earlier. In this way, users experience careful guidance through each step of the workflow.