Radiofrequency Identification (RFID) Based System for Sterilization Process Monitoring
A biological indicator system for determining the efficacy of a sterilization process is provided. The system includes a radiofrequency identification sensing board having a radiofrequency identification tag, a microcontroller/digital electronics, a sensing pad, and a circuit coupled to the sensing pad that measures an impedance level or a resistance level of the sensing pad upon exposure to a volatile organic compound. The radiofrequency identification tag includes a radiofrequency integrated circuit and an antenna that communicates wirelessly with a radiofrequency identification reader to transmit data associated with the impedance or resistance levels measured from the sensing pad. The data can be transmitted in real-time during incubation, and this data can then be sent to a user interface to determine the efficacy of a sterilization process when the biological indicator system is placed in a sterilization chamber during a sterilization cycle. A method of using the system is also provided.
1 . A biological indicator system for determining the efficacy of a sterilization process, the biological indicator system comprising:
a radiofrequency identification sensing board comprising a radiofrequency identification tag that includes a radiofrequency integrated circuit and an antenna, a microcontroller, a sensing pad, and a circuit coupled to the sensing pad and configured to measure an impedance level or resistance level of the sensing pad upon exposure to a volatile organic compound.
2 . The biological indicator system of claim 1 , further comprising a biological indicator and a growth medium, wherein the radiofrequency identification sensing board, the biological indicator, and the growth medium are sealed within a container by a cap.
3 . The biological indicator system of claim 2 , wherein a headspace distance between the growth medium and the cap ranges from about 4 millimeters to about 16 millimeters.
4 . The biological indicator system of claim 2 , wherein a filter is disposed between the radiofrequency identification sensing board and the growth medium.
5 . The biological indicator system of claim 4 , wherein the filter includes a polymer coating having a thickness ranging from about 0.01 micrometers to about 5 micrometers.
6 . The biological indicator system of claim 1 , wherein the sensing pad is disposed on a lower surface of the radiofrequency identification sensing board.
7 . The biological indicator system of claim 6 , wherein the sensing pad is in contact with a gap electrode or an interdigitated electrode coated with a film.
8 . The biological indicator system of claim 7 , wherein the gap electrode defines a gap ranging from about 0.01 millimeters to about 0.3 millimeters.
9 . The biological indicator system of claim 7 , wherein the film comprises a polymer and metal nanoparticles.
10 . The biological indicator system of claim 1 , further comprising an array of sensing pads.
11 . The biological indicator system of claim 1 , further comprising an array of radiofrequency indicator tags.
12 . The biological indicator system of claim 1 , further comprising a radiofrequency identification reader coupled to a user interface.
13 . The biological indicator system of claim 12 , wherein the radiofrequency identification reader provides power to the radiofrequency identification sensing board.
14 . The biological indicator system of claim 12 , wherein the radiofrequency tag transmits data to the radiofrequency identification reader at a frequency ranging from about 300 Megahertz to about 3 Gigahertz.
15 . The biological indicator system of claim 12 , wherein the radiofrequency tag transmits data to the radiofrequency identification reader at a frequency ranging from about 3 Megahertz to about 30 Megahertz.
16 . The biological indicator system of claim 1 , wherein the radiofrequency identification sensing board is free of a battery.
17 . The biological indicator system of claim 1 , further comprising a temperature sensor.
18 . A method for determining the efficacy of a sterilization process via a biological indicator system comprising a radiofrequency identification sensing board and a radiofrequency identification reader, the method comprising:
exposing a sensing pad of the radiofrequency identification sensing board to vapor from headspace in a container, wherein the container includes a growth medium and a biological indicator;
measuring an impedance level or a resistance level of the sensing pad; and
sending data associated with the impedance level or the resistance level to a radiofrequency identification tag, wherein the presence of a volatile organic compound is determined if the impedance level or the resistance level is higher than a predetermined baseline impedance level or baseline resistance level of the sensing pad, wherein the presence of the volatile organic compound indicates failure of the sterilization process.
19 . The method of claim 18 , further comprising transmitting the data to a radiofrequency identification reader.
20 . The method of claim 19 , further comprising sending the data from the radiofrequency identification reader to a user interface.
21 . The method of claim 18 , further comprising measuring a temperature within the container via a temperature sensor.
22 . The method of claim 18 , wherein the radiofrequency identification sensing board comprises a radiofrequency tag that includes a radiofrequency integrated circuit and an antenna, a microcontroller or digital electronics, and an electrical circuit configured to measure the impedance level or the resistance level of the sensing pad.
23 . The method of claim 22 , further comprising an array of radiofrequency indicator tags.
24 . The method of claim 22 , wherein the radiofrequency tag transmits data to the radiofrequency identification reader at a frequency ranging from about 300 Megahertz to about 3 Gigahertz.
25 . The method of claim 22 , wherein the radiofrequency tag transmits data to the radiofrequency identification reader at a frequency ranging from about 3 Megahertz to about 30 Megahertz.
26 . The method of claim 18 , wherein a cap seals the radiofrequency identification sensing board, the biological indicator, and the growth medium within the container, wherein a headspace distance between the growth medium and the radiofrequency identification sensing board ranges from about 4 millimeters to about 16 millimeters.
27 . The method of claim 18 , wherein a filter is disposed between the radiofrequency identification sensing board and the growth medium.
28 . The method of claim 27 , wherein the filter includes a polymer coating having a thickness ranging from about 0.1 micrometers to about 5 micrometers.
29 . The method of claim 18 , wherein the sensing pad is in contact with a gap electrode or an interdigitated electrode coated with a film comprising a polymer and metal nanoparticles.
30 . The method of claim 29 , wherein the gap electrode defines a gap ranging from about 0.01 millimeters to about 0.3 millimeters.
31 . The method of claim 18 , wherein the radiofrequency identification sensing board includes an array of sensing pads.
32 . The method of claim 18 , wherein the radiofrequency identification reader is coupled to a user interface.
33 . The method of claim 18 , wherein the radiofrequency identification reader provides power to the radiofrequency identification sensing board.
34 . The method of claim 18 , wherein the radiofrequency identification sensing board is free of a battery.
35 . The method of claim 18 , wherein the sterilization process utilizes steam, hydrogen peroxide, or ethylene oxide.