Table 2.

The relevant theories of APP interface design.

Design types	Definition	Design principles
User experience design	User experience stands for subjective feelings users feel when using products, including the convenience of use, clarity of information, speed, and accuracy of feedback, etc. [36,37].	A concise and clear interface
		Reasonable functional layout
		Timely and accurate feedback
		Smooth and natural operation
Information architecture design	Information architecture means the process of classifying, organizing, and structuring various information and functions in an APP [38,39].	Clear classification of information
		Navigation consistency
		Clear information hierarchy
Interaction design	It refers to the process of how designers interact with users and apps, covering layout of interface elements, design of functions, presentation of interactive effects, etc. [40,41].	Easy to learn and use
		Natural operation mode
		Timely and accurate interface feedback
		Easy-to-discover and use features
Responsive design	It means that the interface of an APP can automatically adapt to different screen sizes and device types [42,43].	Adapt to multiple screen sizes and device types
Accessibility design	It indicates how a designer can make an APP useable by all people, including users with physical and cognitive disabilities [44,45].	Easy-to-understand interface
		Simple and clear operation method
		Clear and easy-to-understand information