Near static strain measurement with piezoelectric films

Ramanathan, Arun Kumar; Headings, Leon M.; Dapino, Marcelo J.

doi:10.1016/j.sna.2019.111654

Cited by 7 publications

(12 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Strain in the PVDF film is assumed to be uniform through its thickness. The charge Q generated due to a change in the average strain over the film's span is calculated as [32]:…”

Section: Strain-voltage Formulationmentioning

confidence: 99%

“…The charge amplification stage is followed by a unity gain buffer circuit to provide a low impedance interface to the data acquisition system. Letting C S << C F , C F = C C and R F = R C , the voltage output from a charge amplifier at low frequencies and compensated for voltage drift error is expressed in the Laplace domain as [32]: For R F → ∞ and assuming constant capacitance and bias currents, ( 13) can be rewritten in the time domain as:…”

Section: Strain-voltage Formulationmentioning

confidence: 99%

“…Rectangular EMC strips are then stretched to a prestrain of 40% (ϵ a ≜ ϵ b = 0.4) and bonded simultaneously on either face of the core such that they are orthogonal to the rectangular sensors. A PVDF sensor subjected to plane strain and quasistatic loading conditions exhibits high linearity up to 1000 µstrain [32]. For the chosen EMC prestrain of 0.4, the maximum strain on the PVDF sensor due to the initial curvature is about 350 µstrain.…”

Section: Fabrication Processmentioning

confidence: 99%

See 2 more Smart Citations

Self-sensing piezoelectric bistable laminates for morphing structures

Chillara

Ramanathan

Dapino

2020

Smart Mater. Struct.

View full text Add to dashboard Cite

Bistable laminates offer opportunities for shape morphing, energy harvesting, and flow control devices. Smart materials such as piezoelectric macrofiber composites and shape memory alloys have been embedded in bistable laminates to actuate or harvest energy. However, sensor systems capable of measuring bistable shapes and snap-through events are lacking. In this paper, we present curved bistable laminates layered with piezoelectric PVDF films that can sense smooth shape changes as well as abrupt snap-through transitions. Near-static measurement is facilitated by a drift compensated charge amplifier with a large time constant that converts the sensor's charge output into a measurable voltage with minimal drift error. The sensing function is demonstrated on mechanically-prestressed bistable laminates. The laminated composites include two sensor layers such that one measures the changes in curvature and the other measures snap-through events. An analytical model is presented in which strains and curvatures calculated using a laminated-plate model are fed into a linear piezoelectric model to calculate voltage. Shapes measured by the sensors correlate well with shapes measured using a 3D motion capture system. A model-based analysis is performed to understand the laminates' design space.

show abstract

“…Strain in the PVDF film is assumed to be uniform through its thickness. The charge Q generated due to a change in the average strain over the film's span is calculated as [32]:…”

Section: Strain-voltage Formulationmentioning

confidence: 99%

Section: Strain-voltage Formulationmentioning

confidence: 99%

Section: Fabrication Processmentioning

confidence: 99%

See 1 more Smart Citation

Self-sensing piezoelectric bistable laminates for morphing structures

Chillara

Ramanathan

Dapino

2020

Smart Mater. Struct.

View full text Add to dashboard Cite

show abstract

“…The studies [28][29][30] introduced an active feedback network in parallel with the existing feedback network of the charge amplifier, in which the active feedback compensation performed closed-loop proportionalintegral control. By duplicating an additional charge amplifier and then using a pair of charge amplifiers in parallel, the studies [31,32] proposed a differential topology to diminish the drift in the final output.…”

Section: Introductionmentioning

confidence: 99%

Low-frequency compensation of piezoelectric force sensors for servo systems

Lu¹,

Lyu²,

Jeng³

2022

Meas. Sci. Technol.

View full text Add to dashboard Cite

This paper presents a force/disturbance observer that compensates for the low-frequency response of a piezoelectric force sensor. Although the piezoelectric force sensor has many salient features, it is unable to measure dc and quasi-dc forces. The proposed observer compensates for this low-frequency deficiency, enabling the piezoelectric force sensor to be used in a servo system. Compared with previous studies, the proposed scheme requires redesigning neither the sensor structure nor sensing circuitry and can be easily integrated into an existing measurement system. As a by-product, the proposed observer also produces a disturbance estimate that can be used to enhance the robustness of a servo system. This paper reports experimental results of force control and position control for a linear motion platform equipped with a piezoelectric force sensor and a strain gauge-based load cell. The force control results indicate that the control system using the proposed observer can achieve a wider bandwidth than that using the load cell as a feedback-sensing device. In a comparative study, the position control results further demonstrate the proposed observer’s effectiveness in diminishing the piezoelectric sensor’s low-frequency deficiency. Moreover, the disturbance estimate produced by the proposed observer is experimentally introduced to the position control system, showing an enhanced tracking performance in terms of the root-mean-square error.

show abstract

“…The voltage gain and time constant of the charge amplifier are primarily determined by its feedback capacitance and resistance. Increasing the time constant comes at the expense of a reduction in voltage gain and increased signal error due to voltage drift and pyroelectricity [12,13]. Therefore, in order to measure static differential pressure with high resolution, the charge per unit of applied pressure, defined as the charge sensitivity of the sensor, should to maximized.…”

Section: Introductionmentioning

confidence: 99%

Differential pressure sensor using flexible piezoelectrics with pyroelectric compensation

Ramanathan¹,

Headings²,

Dapino³

2021

Smart Mater. Struct.

View full text Add to dashboard Cite

Polyvinylidene fluoride (PVDF) is a mechanically tough, low density piezoelectric polymer commercially available as a flexible film that can be conformed to arbitrarily-shaped surfaces using simple adhesive bonding. A fundamental challenge that prevents the implementation of piezoelectric sensors for pressure sensing applications is their inability to measure static or very low frequency signals. Further, due to their large pyroelectric constants, they are limited to measurements where the rate of change in temperature is smaller than the lower cutoff frequency of the system. Under steady flow conditions, the cantilever unimorph possesses the highest sensitivity compared to other conventional configurations such as compression, doubly clamped unimorphs, or diaphragms. However, to preserve the overall noninvasive nature and linearity of the sensor, it is necessary to optimize the geometry and material properties in order to maximize charge output while minimizing deflection. To address these challenges, this work focuses on the development of a cantilever PVDF unimorph for static differential pressure measurement with pyroelectric compensation. A design optimization procedure to maximize the charge sensitivity of a cantilever unimorph is presented and the optimized cantilever is interfaced with a large-time-constant, drift-compensated charge amplifier for near-static pressure measurements. Voltage error due to temperature changes accompanying the input flow is compensated using a compressive mode sensor and an empirical compensation algorithm. Within the investigated range, the sensitivity of the fabricated sensor is 1.05 mV Pa−1 with an average resolution of 10 Pa and 97.3% linearity.

show abstract

Near static strain measurement with piezoelectric films

Cited by 7 publications

References 25 publications

Self-sensing piezoelectric bistable laminates for morphing structures

Self-sensing piezoelectric bistable laminates for morphing structures

Low-frequency compensation of piezoelectric force sensors for servo systems

Differential pressure sensor using flexible piezoelectrics with pyroelectric compensation

Contact Info

Product

Resources

About