A method of assessing a susceptibility of bacteria to an anti-infective, the method comprising: introducing a fluid sample to a first surface and a second surface, wherein the first surface and the second surface are filter surfaces, wherein the second surface is separated from the first surface; exposing the first surface comprising the bacteria to a first solution; exposing the second surface comprising the bacteria to a second solution; wherein at least one of the second surface and the second solution comprises an anti-infective; adding a known concentration of glucose to the first solution before sampling the first solution and adding the same known concentration of glucose to the second solution before sampling the second solution; sampling the first solution after exposing the first solution to the first surface; sampling the second solution after exposing the second solution to the second surface; monitoring a first electrical characteristic of a first sensing device at a first functionalization layer exposed to the first solution sampled, wherein the first electrical characteristic is at least one of a voltage, an impedance, and a current of the first sensing device, wherein the first functionalization layer covers a first working electrode of the first sensing device; monitoring a second electrical characteristic of a second sensing device at a second functionalization layer exposed to the second solution sampled, wherein the second electrical characteristic is at least one of a voltage, an impedance and a current of the second sensing device, wherein the second functionalization layer covers a second working electrode of the second sensing device, wherein the first sensing device is a first glucose sensor and the second sensing device is a second glucose sensor; and comparing the first electrical characteristic and the second electrical characteristic by determining a difference between the first electrical characteristic and the second electrical characteristic to assess the susceptibility of the bacteria to the anti-infective, wherein the difference between the first electrical characteristic and the second electrical characteristic is a result of a difference in glucose concentration of the first solution and the second solution. introducing a fluid sample to a first surface and a second surface, wherein the first surface and the second surface are filter surfaces, wherein the second surface is separated from the first surface; exposing the first surface comprising the bacteria to a first solution; exposing the second surface comprising the bacteria to a second solution; wherein at least one of the second surface and the second solution comprises an anti-infective; adding a known concentration of glucose to the first solution before sampling the first solution and adding the same known concentration of glucose to the second solution before sampling the second solution; sampling the first solution after exposing the first solution to the first surface; sampling the second solution after exposing the second solution to the second surface; monitoring a first electrical characteristic of a first sensing device at a first functionalization layer exposed to the first solution sampled, wherein the first electrical characteristic is at least one of a voltage, an impedance, and a current of the first sensing device, wherein the first functionalization layer covers a first working electrode of the first sensing device; monitoring a second electrical characteristic of a second sensing device at a second functionalization layer exposed to the second solution sampled, wherein the second electrical characteristic is at least one of a voltage, an impedance and a current of the second sensing device, wherein the second functionalization layer covers a second working electrode of the second sensing device, wherein the first sensing device is a first glucose sensor and the second sensing device is a second glucose sensor; and comparing the first electrical characteristic and the second electrical characteristic by determining a difference between the first electrical characteristic and the second electrical characteristic to assess the susceptibility of the bacteria to the anti-infective, wherein the difference between the first electrical characteristic and the second electrical characteristic is a result of a difference in glucose concentration of the first solution and the second solution.