Graphene transistors on microbial cellulose

1. A device comprising:

a biopolymer membrane comprising a biopolymer;

a passivation layer on the biopolymer membrane;

a graphene layer on the passivation layer;

a source electrode on the graphene layer; and

a drain electrode on the graphene layer;

wherein the graphene layer extends between the source electrode and the drain electrode;

wherein a thickness of the biopolymer membrane is less than 10 μm; and

wherein the biopolymer membrane comprises microbial cellulose.

2. The device of claim 1 wherein:

the source electrode extends over the passivation layer; and

the drain electrode extends over the passivation layer.

3. The device of claim 1 wherein the passivation layer comprises a dielectric.

4. The device of claim 1 wherein the passivation layer comprises:

a dielectric on the biopolymer membrane; and

a bio-compatible polymer on the dielectric.

5. The device of claim 4 :

wherein the dielectric comprises Al 2 O 3 , SiO 2 , or HfO 2 ; and

wherein the bio-compatible polymer comprises SU-8, polyimide, parylene, or polydimethylsiloxane (PDMS).

6. The device of claim 1 wherein the passivation layer comprises a bio-compatible polymer on the biopolymer membrane.

7. The device of claim 6 wherein the bio-compatible polymer comprises SU-8, polyimide, parylene, or PDMS.

8. The device of claim 1 wherein the graphene layer is a chemical vapor deposition-grown graphene.

9. The device of claim 1 further comprising:

a gate insulator on the graphene layer; and

a gate electrode on the gate insulator;

wherein the gate electrode is between the source electrode and the drain electrode.

10. The device of claim 9 wherein the gate insulator comprises a dielectric.

11. The device of claim 1 wherein the device is a sensor or a transistor.

12. The device of claim 1 :

wherein a carrier mobility is greater than 1,600 cm 2 /Vs; and

wherein a flexibility is up to 18% strain.