Wireless battery-free diagnostic mouth guard
Various examples of methods, systems, and apparatus are provided for monitoring using an improved mouth guard apparatus. In one example, a battery-free diagnostic mouth guard includes a biting force-voltage transducer comprising a piezoelectric film; a compact resonance tank comprising a wireless sensor; and a transmitting antenna for transmitting sensing data. A piezo-voltage from the biting force-voltage transducer can bias a varactor diode loaded on the wireless sensor whose response frequency is tuned due to a capacitance change of the varactor diode. In some implementations, an external processing equipment can wirelessly detect a frequency shift of the varactor diode integrated resonator. In another example, a method includes detecting a biting force via a biting force-voltage transducer; biasing a varactor diode with a voltage from the transducer; tuning a response frequency of a split ring resonator using a capacitance change of the varactor diode; and emitting sensing data at the response frequency.
1. A battery-free diagnostic mouth guard configured for positioning between teeth of a user, the mouth guard comprising:
a biting force-voltage transducer comprising a piezoelectric film;
a split ring resonator coupled to the biting force-voltage transducer;
a varactor diode configured to load the split ring resonator; and
a transmitting antenna, coupled to the split ring resonator, for transmitting sensing data from the biting force-voltage transducer;
wherein a piezo-voltage from the biting force-voltage transducer biases the varactor diode loaded on the split ring resonator so as to change capacitance of the varactor diode and to cause a shift in resonant frequency of the split ring resonator.
2. The battery-free diagnostic mouth guard of claim 1 , wherein the split ring resonator comprises a metamaterial particle.
3. The battery-free diagnostic mouth guard of claim 1 , wherein the split ring resonator comprises at least two concentric rings with a slit carved on each concentric ring.
4. The battery-free diagnostic mouth guard of claim 3 , wherein the varactor diode is connected across the slit of one of the at least two concentric rings.
5. The battery-free diagnostic mouth guard of claim 1 , wherein the piezoelectric film is coated with a layer of Polydimethylsiloxane (PDMS).
6. The battery-free diagnostic mouth guard of claim 1 , wherein the transmitting antenna comprises a dipole antenna.
7. The battery-free diagnostic mouth guard of claim 6 , wherein the dipole antenna is coupled to the split ring resonator.
8. The battery-free diagnostic mouth guard of claim 1 , wherein the split ring resonator comprises a flexible substrate.
9. A system comprising:
a battery-free diagnostic mouth guard configured for positioning between teeth of a user, the battery-free diagnostic mouth guard comprising:
a biting force-voltage transducer comprising a piezoelectric film;
a split ring resonator; and
a transmitting antenna for transmitting sensing data from the biting force-voltage transducer,
wherein a piezo-voltage from the biting force-voltage transducer biases a varactor diode loaded on the split ring resonator so as to change capacitance of the varactor diode and to cause a shift in resonant frequency of the split ring resonator; and
external processing equipment configured to wirelessly detect a frequency shift of the resonant frequency induced by the capacitance change of the varactor diode.
10. The system of claim 9 , wherein the external processing equipment comprises a receiving antenna, wherein the external processing equipment is configured to read out the sensing data received by the receiving antenna.
11. The system of claim 9 , wherein the sensing data is transmitted over a MHz medical implant communication service (MICS) band or an industry science medicine (ISM) band.
12. The system of claim 11 , wherein the wireless sensor is configured to resonate at a frequency corresponding to the MICS band or the ISM band.
13. The system of claim 12 , wherein the wireless sensor is configured to resonate in a 5.8 GHz band.
14. The system of claim 9 , wherein the resonant frequency of the split ring resonator exhibits a substantially linear frequency shift in response to force applied to the biting force-voltage transducer.
15. A method comprising:
positioning a mouth guard between teeth of a subject, the mouth guard comprising a varactor diode, a split ring resonator, and a biting force-voltage transducer on a mouth guard substrate, the varactor diode configured to load the split ring resonator;
generating, by the biting force-voltage transducer, a voltage corresponding to a biting force on the mouth guard substrate;
biasing the varactor diode by applying the voltage from the biting force-voltage transducer across the varactor diode;
tuning a resonant frequency of the split ring resonator based on a capacitance change of the varactor diode induced by the biasing; and
emitting sensing data from the biting force-voltage transducer.
16. The method of claim 15 , wherein the biting force-voltage transducer comprises a piezoelectric film.
17. The method of claim 16 , wherein the voltage generated via the biting force-voltage transducer exhibits a substantially linear change above a force of 240 N.
18. The method of claim 15 , further comprising determining a frequency shift of the resonant frequency based upon the sensing data.
19. The method of claim 18 , wherein the resonant frequency is in a 2.4 GHz band.