Vernier does not currently carry any type of microelectrode. This includes pH, dissolved oxygen, and/or any type of ion-specific microelectrode.
If you are looking for microelectrodes for your application, you may want to contact Microelectrodes, Inc. See the link below.
http://www.microelectrodes.com/
If you are looking for microelectrodes for dissolved oxygen, you may want to contact Pyro Science. See the link below.
Please note that products from these vendors are not currently compatible with Logger Pro.