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Microfabrication and integration of a sol-gel PZT folded spring energy harvester.

Lueke J, Badr A, Lou E, Moussa WA - Sensors (Basel) (2015)

Bottom Line: A feasibility study was undertaken with the designed conditioning circuitry to determine the effect of the input parameters on the overall performance of the circuit.The efficiency and charging current must be balanced to achieve a high output and a reasonable output current.The development of the complete energy harvesting system allows for the direct integration of the energy harvesting technology into existing power management schemes for wireless sensing.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University of Alberta, University of Alberta, Edmonton, AB T6G 2G8, Canada. lueke@ualberta.ca.

ABSTRACT
This paper presents the methodology and challenges experienced in the microfabrication, packaging, and integration of a fixed-fixed folded spring piezoelectric energy harvester. A variety of challenges were overcome in the fabrication of the energy harvesters, such as the diagnosis and rectification of sol-gel PZT film quality and adhesion issues. A packaging and integration methodology was developed to allow for the characterizing the harvesters under a base vibration. The conditioning circuitry developed allowed for a complete energy harvesting system, consisting a harvester, a voltage doubler, a voltage regulator and a NiMH battery. A feasibility study was undertaken with the designed conditioning circuitry to determine the effect of the input parameters on the overall performance of the circuit. It was found that the maximum efficiency does not correlate to the maximum charging current supplied to the battery. The efficiency and charging current must be balanced to achieve a high output and a reasonable output current. The development of the complete energy harvesting system allows for the direct integration of the energy harvesting technology into existing power management schemes for wireless sensing.

No MeSH data available.


Related in: MedlinePlus

Overlapping Etch Areas releasing and defining the cross section of the harvesters [9,19].
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sensors-15-12218-f009: Overlapping Etch Areas releasing and defining the cross section of the harvesters [9,19].

Mentions: The last microfabrication challenge encountered in the development of the harvesters involved the release of the harvesters and preservation of the cross section of the structural members of the harvesters. As shown as Section “G. Definition and Release of the Harvesters” in Figure 1, two sequential deep reactive ion etches (DRIE) were required to define the geometry of the folded springs and release the harvesters. The process uniformity of the DRIE process coupled with the thickness variation of the silicon wafer selected for fabrication can cause a significant difficulty in uniformity and accuracy of the etch depth. The DRIE non-uniformity is a function of the overall depth, therefore the total error in uniformity and etch depth increases cumulatively with etch depth [23,24,25,26,27]. This variability ultimately causes individual devices, of the same design on the same wafer, to have differing natural frequencies as discussed in [5]. There have been some attempts to tune the parameters of the DRIE process, such as RF power, chemistries used in the etch, cooling backpressure, dummy structures, to achieve a more consistent and accurate etch [23,24,25,26,27,28]. The methodology used to define the planar geometry and release the energy harvesters is based upon overlapping the etched volumes created from two sequential etch steps, as shown in Figure 9.


Microfabrication and integration of a sol-gel PZT folded spring energy harvester.

Lueke J, Badr A, Lou E, Moussa WA - Sensors (Basel) (2015)

Overlapping Etch Areas releasing and defining the cross section of the harvesters [9,19].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507646&req=5

sensors-15-12218-f009: Overlapping Etch Areas releasing and defining the cross section of the harvesters [9,19].
Mentions: The last microfabrication challenge encountered in the development of the harvesters involved the release of the harvesters and preservation of the cross section of the structural members of the harvesters. As shown as Section “G. Definition and Release of the Harvesters” in Figure 1, two sequential deep reactive ion etches (DRIE) were required to define the geometry of the folded springs and release the harvesters. The process uniformity of the DRIE process coupled with the thickness variation of the silicon wafer selected for fabrication can cause a significant difficulty in uniformity and accuracy of the etch depth. The DRIE non-uniformity is a function of the overall depth, therefore the total error in uniformity and etch depth increases cumulatively with etch depth [23,24,25,26,27]. This variability ultimately causes individual devices, of the same design on the same wafer, to have differing natural frequencies as discussed in [5]. There have been some attempts to tune the parameters of the DRIE process, such as RF power, chemistries used in the etch, cooling backpressure, dummy structures, to achieve a more consistent and accurate etch [23,24,25,26,27,28]. The methodology used to define the planar geometry and release the energy harvesters is based upon overlapping the etched volumes created from two sequential etch steps, as shown in Figure 9.

Bottom Line: A feasibility study was undertaken with the designed conditioning circuitry to determine the effect of the input parameters on the overall performance of the circuit.The efficiency and charging current must be balanced to achieve a high output and a reasonable output current.The development of the complete energy harvesting system allows for the direct integration of the energy harvesting technology into existing power management schemes for wireless sensing.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University of Alberta, University of Alberta, Edmonton, AB T6G 2G8, Canada. lueke@ualberta.ca.

ABSTRACT
This paper presents the methodology and challenges experienced in the microfabrication, packaging, and integration of a fixed-fixed folded spring piezoelectric energy harvester. A variety of challenges were overcome in the fabrication of the energy harvesters, such as the diagnosis and rectification of sol-gel PZT film quality and adhesion issues. A packaging and integration methodology was developed to allow for the characterizing the harvesters under a base vibration. The conditioning circuitry developed allowed for a complete energy harvesting system, consisting a harvester, a voltage doubler, a voltage regulator and a NiMH battery. A feasibility study was undertaken with the designed conditioning circuitry to determine the effect of the input parameters on the overall performance of the circuit. It was found that the maximum efficiency does not correlate to the maximum charging current supplied to the battery. The efficiency and charging current must be balanced to achieve a high output and a reasonable output current. The development of the complete energy harvesting system allows for the direct integration of the energy harvesting technology into existing power management schemes for wireless sensing.

No MeSH data available.


Related in: MedlinePlus