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Design, fabrication, and implementation of a wireless, passive implantable pressure sensor based on magnetic higher-order harmonic fields.

Tan EL, DeRouin AJ, Pereles BD, Ong KG - Biosensors (Basel) (2011)

Bottom Line: This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting.The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi.In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA. eltan@mtu.edu.

ABSTRACT
A passive and wireless sensor was developed for monitoring pressure in vivo. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is an airtight chamber sealed with an elastic pressure membrane. A strip of magnetically-soft material is attached to the bottom of the chamber and a permanent magnet strip is embedded inside the membrane. Under the excitation of an externally applied AC magnetic field, the magnetically-soft strip produces a higher-order magnetic signature that can be remotely detected with an external receiving coil. As ambient pressure varies, the pressure membrane deflects, altering the separation distance between the magnetically-soft strip and the permanent magnet. This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting. The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi. In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment.

No MeSH data available.


Related in: MedlinePlus

The maximum amplitude of the 2nd-order harmonic fields exhibited by electroplated nickel-iron alloys plated for 0.5, 1, 2, 4, and 8 h normalized to the sample mass.
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biosensors-01-00134-f005: The maximum amplitude of the 2nd-order harmonic fields exhibited by electroplated nickel-iron alloys plated for 0.5, 1, 2, 4, and 8 h normalized to the sample mass.

Mentions: The characteristic of electroplated nickel-iron alloy as a function of plating duration was also investigated. Copper substrates were separately electroplated with plating durations of 0.5, 1, 2, 4, and 8 h while maintaining the condition of other plating parameters (i.e., current density, temperature, and pH) throughout. The BH responses of these samples are plotted in Figure 3 with the saturation magnetization Ms, coercivity Hc, and anisotropy field Hk listed in Table 1. As shown in the table, the Ms and Hk of the samples increased with plating duration up to 2 h, and then reduced. Conversely, Hc demonstrated an initial decrease and then increased with higher plating time. It is believed that the initial increase in the soft ferromagnetic behavior at low plating time was due to the formation of a thicker, more uniform coating. However, the reduction of the soft magnetic behavior at thicker samples could be explained by the increase in internal stress within the thick layers, which led to an increase in magnetic coercivity. Since the higher-order response of a material is a direct reflection of the permeability and coercivity of the sample, the same pattern was observed in the higher-order response versus plating duration (see Figure 4 and Figure 5). Figure 4 indicates the 2nd-order harmonic fields generated by the electroplated soft magnetic materials are equivalent to those generated by commercial soft magnetic materials such as Metglas 2826MB (the 2nd-order harmonic response of Metglas 2826MB was described in the previous work [11,12]).


Design, fabrication, and implementation of a wireless, passive implantable pressure sensor based on magnetic higher-order harmonic fields.

Tan EL, DeRouin AJ, Pereles BD, Ong KG - Biosensors (Basel) (2011)

The maximum amplitude of the 2nd-order harmonic fields exhibited by electroplated nickel-iron alloys plated for 0.5, 1, 2, 4, and 8 h normalized to the sample mass.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4264347&req=5

biosensors-01-00134-f005: The maximum amplitude of the 2nd-order harmonic fields exhibited by electroplated nickel-iron alloys plated for 0.5, 1, 2, 4, and 8 h normalized to the sample mass.
Mentions: The characteristic of electroplated nickel-iron alloy as a function of plating duration was also investigated. Copper substrates were separately electroplated with plating durations of 0.5, 1, 2, 4, and 8 h while maintaining the condition of other plating parameters (i.e., current density, temperature, and pH) throughout. The BH responses of these samples are plotted in Figure 3 with the saturation magnetization Ms, coercivity Hc, and anisotropy field Hk listed in Table 1. As shown in the table, the Ms and Hk of the samples increased with plating duration up to 2 h, and then reduced. Conversely, Hc demonstrated an initial decrease and then increased with higher plating time. It is believed that the initial increase in the soft ferromagnetic behavior at low plating time was due to the formation of a thicker, more uniform coating. However, the reduction of the soft magnetic behavior at thicker samples could be explained by the increase in internal stress within the thick layers, which led to an increase in magnetic coercivity. Since the higher-order response of a material is a direct reflection of the permeability and coercivity of the sample, the same pattern was observed in the higher-order response versus plating duration (see Figure 4 and Figure 5). Figure 4 indicates the 2nd-order harmonic fields generated by the electroplated soft magnetic materials are equivalent to those generated by commercial soft magnetic materials such as Metglas 2826MB (the 2nd-order harmonic response of Metglas 2826MB was described in the previous work [11,12]).

Bottom Line: This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting.The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi.In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA. eltan@mtu.edu.

ABSTRACT
A passive and wireless sensor was developed for monitoring pressure in vivo. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is an airtight chamber sealed with an elastic pressure membrane. A strip of magnetically-soft material is attached to the bottom of the chamber and a permanent magnet strip is embedded inside the membrane. Under the excitation of an externally applied AC magnetic field, the magnetically-soft strip produces a higher-order magnetic signature that can be remotely detected with an external receiving coil. As ambient pressure varies, the pressure membrane deflects, altering the separation distance between the magnetically-soft strip and the permanent magnet. This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting. The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi. In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment.

No MeSH data available.


Related in: MedlinePlus