Chemical sensors with non-covalent surface modification of graphene

Abstract

Embodiments herein relate to chemical sensors, devices and systems including the same, and related methods. In an embodiment, a medical device is included. The medical device can include a graphene varactor. The graphene varactor can include a graphene layer and a self-assembled monolayer disposed on an outer surface of the graphene layer through π-π stacking interactions. The self-assembled monolayer can provide a Langmuir theta value of at least 0.9. The self-assembled monolayer can include polycyclic aromatic hydrocarbons, tetraphenylporphyrins or derivatives thereof, metallotetraphenylporphyrins, or aromatic cyclodextrins. Other embodiments are also included herein.

1 . A medical device comprising:
 a graphene varactor comprising:
 a graphene layer; 
 a self-assembled monolayer disposed on an outer surface of the graphene layer through π-π stacking interactions; and 
   wherein the self-assembled monolayer provides a Langmuir theta value of at least 0.9.   
     
     
         2 . The medical device of  claim 1 , the self-assembled monolayer comprising one or more tetraphenylporphyrins, or derivatives thereof. 
     
     
         3 . The medical device of  claim 1 , the self-assembled monolayer comprising: 
       
         
           
           
               
               
           
         
       
       wherein n is any integer from 1 to 5; m is 1 or 2; R 1  through R 8  comprise —H; —X, where X comprises a halogen atom; —R 9 ; —R 10 OH; R 11 COOH; —R 12 COOR 13 ; —R 14 OR 15 ; —R 16 COH; —R 17 COR 18 ; —R 19 NH 3   + ; —R 20 NH 2 ; —R 21 NR 22 ; —R 23 NR 24 R 25+ ; —R 26 X or —R 27 COX, where X is any halogen atom; —R 28 SH or any combination thereof; and R 9  through R 28  comprise any linear or branched C 1 -C 12  alkyl, C 1 -C 12  alkenyl, C 1 -C 12  alkynyl, or any combination thereof, or can be absent such that the remaining portion of the functional group is covalently bound directly to one or more carbon atoms of the base aromatic ring structure. 
     
     
         4 . The medical device of  claim 1 , comprising a plurality of graphene varactors configured in an array on the medical device. 
     
     
         5 . The medical device of  claim 1 , wherein the self-assembled monolayer provides a Langmuir theta value of at least 0.98. 
     
     
         6 . The medical device of  claim 1 , wherein the self-assembled monolayer provides coverage over the graphene from 50% to 150% by surface area. 
     
     
         7 . The medical device of  claim 1 , wherein the self-assembled monolayer provides coverage over the graphene from 99% to 120% by surface area. 
     
     
         8 . A method of modifying a surface of graphene to create a graphene varactor, the method comprising:
 forming a self-assembled monolayer on an outer surface of a graphene layer of the graphene varactor through π-π stacking interactions;   quantifying the extent of surface coverage of the self-assembled monolayer using contact angle goniometry, Raman spectroscopy, or X-Ray photoelectron spectroscopy;   selecting derivatized graphene layers that exhibit a Langmuir theta value of at least 0.9.   
     
     
         9 . The method of  claim 8 , wherein selecting derivatized graphene layers includes selecting derivatized graphene layers that exhibit a Langmuir theta value of at least 0.98. 
     
     
         10 . The method of  claim 8 , wherein the self-assembled monolayer provides coverage over the graphene from 50% to 150% by surface area. 
     
     
         11 . The method of  claim 8 , wherein the self-assembled monolayer provides coverage over the graphene from 99% to 120% by surface area. 
     
     
         12 . The method of  claim 8 , wherein the self-assembled monolayer comprises at least one selected from the group consisting of polycyclic aromatic hydrocarbons comprising 3 to 10 aromatic rings; tetraphenylporphyrins or derivatives thereof; metallotetraphenylporphyrins or derivatives thereof; and aromatic cyclodextrins. 
     
     
         13 . A method for detecting an analyte comprising:
 collecting a gaseous sample from a patient;   contacting the gaseous sample with one or more graphene varactors, each of the one or more graphene varactors comprising:
 a graphene layer; 
 a self-assembled monolayer disposed on an outer surface of the graphene layer through π-π stacking interactions; and 
   wherein the self-assembled monolayer provides a Langmuir theta value of at least 0.9.   
     
     
         14 . The method of  claim 13 , further comprising measuring a differential response in a capacitance of the one or more graphene varactors due to the binding of one or more analytes present in the gaseous sample. 
     
     
         15 . The method of  claim 13 , wherein the self-assembled monolayer comprises at least one selected from the group consisting of polycyclic aromatic hydrocarbons comprising 3 to 10 aromatic rings; tetraphenylporphyrins or derivatives thereof; metallotetraphenylporphyrins or derivatives thereof; and aromatic cyclodextrins. 
     
     
         16 . The method of  claim 13 , wherein selecting derivatized graphene layers includes selecting derivatized graphene layers that exhibit a Langmuir theta value of at least 0.98. 
     
     
         17 . The method of  claim 13 , wherein the self-assembled monolayer provides coverage over the graphene from 50% to 150% by surface area. 
     
     
         18 . The method of  claim 13 , wherein the self-assembled monolayer provides coverage over the graphene from 99% to 120% by surface area.