GLASSY CARBON

Baked from a polymer

Glassy carbon is made by controlled pyrolysis of a polymeric precursor in an inert atmosphere. Volatile components — mostly hydrogen, oxygen, and nitrogen — are driven off, and the remaining carbon atoms reorganize into an interconnected network of curved graphitic domains.

polymer + heat, no oxygen → glassy carbon

Unlike graphite, these domains never line up into long crystalline layers — so there are no weak cleavage planes.

GLASSY CARBON

What that structure buys you

Chemically inert Resists acidic and alkaline electrolytes with minimal corrosion

Conductive enough Lower than graphite, yet fine for fast electron transfer

Hard and stable High hardness, wear resistance, and low thermal expansion

Wide potential window Slow hydrogen and oxygen evolution, low background current

Its surface can also be tuned through functionalization, plasma treatment, or catalytic nanomaterials.

GLASSY CARBON • MICROFABRICATION

Patterned like a photoresist

1. Pattern Thick SU-8 epoxy photoresist exposed with standard UV lithography

2. Pyrolyze Heat in an inert atmosphere; non-carbon elements leave as gas

3. Result 3D glassy-carbon electrodes with the original geometry largely intact

The structure does shrink isotropically during pyrolysis, so designers must plan for it — but the shape stays reproducible.

GLASSY CARBON • IN THE BODY

Built for biology

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Glassy carbon shows minimal cytotoxicity and favorable interactions with tissue, plus strong resistance to corrosion and biofouling in physiological solutions like PBS. It's already used in biosensors, neural interfaces, fuel cells, and batteries.

Key idea Conductive, inert, patternable, and biocompatible — that combination is why glassy carbon is the electrode material for this course's device.

UNIT 12 STUDY COMPLETE

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Ready for the Fab Challenge?

You've covered a pyrolyzed, non-graphitizing carbon that can be patterned with photolithography.