For this first sensor, it is an NFC reader. It is able to take something small and tangible and able to read codes or information from the piece. NFC stands for Near field Communication and is mostly used in credit cards and other applications where objects will be very close to each other, but I have never seen it being used like this. It is really interesting because by utilizing it people can open phones and computers because the password is encrypted on the ring or another device. I think this could be very useful in other applications like hiding information so that people can be found out who they are if they are in an accident or they can pass sensitive information or have sign-ins for work with just running their hands pasta reader.
This sensor is an eTape Liquid level Sensor. I have never seen a sensor like this but adafruit says that it is a lot like a photocell. Because of my eyesight, I sometimes have a hard time reading measurements. I know something like the project on adafruit would help a lot of people. It is able to display measurements when measuring liquids for anything. This could come in very useful with measuring liquids for paints or chemicals for experiments.
This project uses a IR sensor to receive signals from a remote which can have multiple functions based on the code given to it. It works based on deflected signals sent out and then received by the IR and interpreted by the arduino and then executed by functions. I find this fascinating because it is really cool how small the sensor can be and have a huge outcome. This could be used in almost anything that needs to transfer information from one area to another.