Ernesto Suaste-Gómez

Opacity Sensor Based on Photovoltaic Effect of Ferroelectric PLZT Ceramic With Pt Wire Implant

This work reports the formation of a ferroelectric poled bulk ceramic structure as opacity sensor (OPS) and the improved photovoltaic output of the lead lanthanum zirconate titanate (PLZT) employed. This ceramic was implanted during its fabrication with a platinum wire (Pt-wire) which works as an internal electrode. Photovoltaic current have been measured in PLZT with Pt-wire under chopped LASER beam illumination. This photovoltaic current was measured on the upper face of a sensor in order to obtain a characterization curve. Different thin materials were put on the OPS in order to determine its opacity according to their thickness and viscosity. Opacity is a condition in which a material partially or completely impedes the passage of light beam. The results indicated that the photovoltaic current response was less than 700 pA at 160 mW/cm2 maximum power of illumination; 2-D scans were obtained from fruit tissues, vegetal oils and thin materials at 160 mW/cm2 of illumination in order to get a representation of opacity images.

Developing an Ear Prosthesis Fabricated in Polyvinylidene Fluoride by a 3D Printer with Sensory Intrinsic Properties of Pressure and Temperature

An ear prosthesis was designed in 3D computer graphics software and fabricated using a 3D printing process of polyvinylidene fluoride (PVDF) for use as a hearing aid. In addition, the prosthesis response to pressure and temperature was observed. Pyroelectric and piezoelectric properties of this ear prosthesis were investigated using an astable multivibrator circuit, as changes in PVDF permittivity were observed according to variations of pressure and temperature. The results show that this prosthesis is reliable for use under different conditions of pressure (0 Pa to 16,350 Pa) and temperature (2 °C to 90 °C). The experimental results show an almost linear and inversely proportional behavior between the stimuli of pressure and temperature with the frequency response. This 3D-printed ear prosthesis is a promising tool and has a great potentiality in the biomedical engineering field because of its ability to generate an electrical potential proportional to pressure and temperature, and it is the first time that such a device has been processed by the additive manufacturing process (3D printing). More work needs to be carried out to improve the performance, such as electrical stimulation of the nervous system, thereby extending the purpose of a prosthesis to the area of sensory perception.

Thermal Effusivity of the Pb0.88Ln0.08Ti0.98Mn0.02O3 (Ln=La, Eu) Ferroelectric Ceramic System by Inverse Photopyroelectric Technique

In this work, the thermal effusivities of Pb0.88Ln0.08Ti0.98Mn0.02O3 (Ln=La, Eu) ferroelectric ceramics are studied since it can be use as pyroelectric detectors. Photothermal techniques were used to determine thermal effusivity. The preparation of the ceramics was perform in our laboratory by using the oxide-mixing conventional method. It should be noticed that these ceramics were taken in an unpoled state. All measurements were made at room temperature.

A new spontaneous pupillary oscillation-based verification system

A novel pupillary-based verification system is introduced, along with the early identity authentication results and analysis, based on the spatio-temporal features computed from the spontaneous pupillary oscillations. The authors demonstrate that this biometric trait has the capability to provide enough discriminative information to authenticate the identity of a subject. A new methodology to compute the spatio-temporal biometric template recordings of the pupil area changes, in a video-oculography sequence under constant luminance level, is also introduced in this paper. According to the authors’ knowledge, there is no evidence that other attempts were made, addressing this methodology to distinguish individuals based on the spatio-temporal representations, computed from the normal dilation-contraction behavior of the pupil. In this work, liveness will be detected by using the information obtained from the spontaneous pupillary oscillation mechanism. Preliminary experiments were conducted by using a particular own collected database, resulting in a (Equal Error Rate) in the order of 0.2338%.

A Piezoelectric Plethysmograph Sensor Based on a Pt Wire Implanted Lead Lanthanum Zirconate Titanate Bulk Ceramic

This work reports on the development of a Lead Lanthanum Zirconate Titanate (PLZT) bulk ferroelectric poled ceramic structure as a Piezoelectric Plethysmograph (PZPG) sensor. The ceramic was implanted during its fabrication with a platinum (Pt) wire which works as an internal electrode. The ceramic was then submitted to an experimental setup in order to validate and determine the Pt-wire mechanical effects. This PZPG sensor was also mounted on a finger splint in order to measure the blood flow that results from the pulsations of blood occurring with each heartbeat. Fingertip pulses were recorded jointly with an ECG signal from a 25 year old male to compare the time shift; the PZPG sensor guarantees the electrical isolation of the patient. The proposed PZPG has several advantages: it can be adjusted for fingertip measurements, but it can easily be extended by means of spare bands, therefore making possible PZPG measurements from different body locations, e.g., forehead, forearm, knee, neck, etc.

Developed and Experimental Evidence of a Ceramic-Controlled Piezoelectric Bulk Implanted with Pt Wire Based on PLZT

This work reports on the formation of a Lead Lanthanum Zirconate Titanate bulk ferroelectric poled ceramic structure as ceramic-controlled piezoelectric, this ceramic was implanted during its fabrication with platinum wire that operates as an internal electrode. The CCP was submitted in two experimental setups to validate and determine the Pt-wire optical and mechanical effects. Dielectric constant was determined on ceramic-controlled piezoelectric with and without Pt wire.

Determination of the Pyroelectric Coefficient for (Bi0.5Na0.5)0.935Ba0.065TiO3 Piezoelectric Ceramics

In this work, the dielectric and pyroelectric characteristics of the (Bi 0.5 Na 0.5 ) 0.935 Ba 0.065 TiO 3 lead-free ferroelectric ceramic are studied in order to determine its usefulness for infrared detectors. Dielectric constant and pyroelectric coefficient of these ceramics were measured. The ceramics present high values of the dielectric constant at its Curie temperature at 425°C. The pyroelectric coefficient was determined by the Byer-Roundy method. The relationship for pyroelectric detectors was calculated and compared with other materials used as infrared detectors.

Development of Poly(vinylidene flouride) Polymer Applied in Force Sensors for Gait Analysis in Wistar Mice of Physiology Research Laboratory

A group of force sensors was designed and manufactured. These are based on piezoelectric poly(vinylidene diflouride) (PVDF) films. These sensors will help evaluate the revascularization process in Wistar mouse legs. The sensors were calibrated from 0.0 to 14.4 g and had an uncertainty of ±7.5 mN.

A Capacitive Humidity Sensor Based on an Electrospun PVDF/Graphene Membrane

Humidity sensors have been widely used in areas such as agriculture, environmental conservation, medicine, instrumentation and climatology. Hydrophobicity is one of the important factors in capacitive humidity sensors: recent research has shown that the inclusion of graphene (G) in polyvinylidene fluoride (PVDF) improves its hydrophobicity. In this context, a methodology to fabricate electrospun membranes of PVDF blended with G was developed in order to improve the PVDF properties allowing the use of PVDF/G membrane as a capacitive humidity sensor. Micrographs of membranes were obtained by scanning electron microscopy to analyze the morphology of the fabricated samples. Subsequently, the capacitive response of the membrane, which showed an almost linear and directly proportional response to humidity, was tested. Results showed that the response time of PVDF/G membrane was faster than that of a commercial DHT11 sensor. In summary, PVDF/G membranes exhibit interesting properties as humidity sensors.

Pyroelectric properties of Pb0.88Ln0.08Ti0.98Mn0.02O3 (Ln=La, Sm, Eu) ferroelectric ceramic system

Abstract In this work, the pyroelectric properties of Pb 0.88 Ln 0.08 Ti 0.98 Mn 0.02 O 3 (Ln=La, Sm, Eu) ferroelectric ceramic system are studied. This type of ferroelectric ceramic presents high values of the following characteristics: dielectric constant, Curie temperature, electromechanical anisotropy, and high frequencies of operation, which make them useful for applications such as ultrasonic transducers in biomedical applications. The relationship between dielectric constant and temperature measurements as well as pyroelectric measurements using the technique of Byer and Roundy were performed. Values of the pyroelectric coefficient and figure of merit for infrared detector materials were obtained to use these ceramics in the detection of infrared radiation, laser power measurements, and solar energy technology.