Electrical and computer engineering doctoral researcher improving acoustic sensors with novel materials and designs

We are constantly surrounded by an abundance of acoustic energy, whether from speech, music, or environmental noise. If captured, these acoustic waves can provide a wealth of information about a person and their surroundings, and be leveraged for multiple applications. Many sensors available today have an acoustic impedance that is much different from the media being monitored, which results in lowered energy density at the transducer element and interference from other sound sources. Working with Dr. James West at Johns Hopkins University, my thesis work has focused on developing and characterizing flexible, impedance-matched acoustic sensors, especially for use on the human body.

Short overview of my research from Three Minute Thesis Competition.

Differences in acoustic impedance cause a significant amount of energy to be reflected at the boundary between the body and air.

Acoustic impedance mismatches in devices, such as stethoscopes, decrease the energy transmitted to the device and allow the signal to be corrupted by airborne noise.


Experience fabricating materials, applying signal processing techniques, and characterizing acoustic sensors

Designing a sensor that can be fabricated to match the acoustic impedance of materials such as skin, wood, and water. When used to pick up body sounds, the device demonstrates comparable performance to a commercially available electronic stethoscope with noise cancellation.

Acoustic sensor design

Using an I-optimal design of experiments to generate a statistical model that specifies the fabrication and characterization conditions necessary for a polymer to target a acoustic specific impedance value with minimum attenuation.

Polymer acoustic impedance matching

Exploring the fabrication and characterization of nanofibers that generate an electrical response and how they might be used to create flexible acoustic sensors.

Electrospun nanofibers

Determining how biomolecules, such as DNA and proteins, can be used to enhance the electrical response of polymers or custom-designed to demonstrate a piezoelectric response.

Polymer-biomolecule hybrid materials

Making the transition to electronic stethoscopes easier for physicians who are accustomed to the sound characteristics of acoustic stethoscopes using signal processing techniques.

Stethoscope equalization matching

Comparing approaches to create and intergrate flexible interconnects with acoustic sensors. One approach involves using a mechanical cutting plotter to cut serpentine patterns into metallized films.

Flexible electronics

Developing an acoustic phantom for improved characterizations and comparisons of body sound monitoring technology.

Acoustic phantom design

Assisting with a study to explore the robustness of using cough, speech, and breathing sounds to detect COVID-19.

Disease detection with sound

Working with musicians at Peabody to compare pickup methods.

Musical instrument pickup

Acoustic sensor demonstrations

Recordings with the original prototype of the impedance-matched sensor for voice, heart sounds, and guitar. Background music is played at a certain level as recorded by the sound level meter. Although the background noise is evident in the recordings made with the ambient microphone, the impedance-matched sensor captures very little of this background noise.


Broad range of technical and interpersonal competencies

Data Analysis

Study and visualize data using programs such as Matlab and R

Design of experiments

Systematically plan experiments with attention to reliability and replicability using JMP

Electronic materials

Fabricate & characterize electrets with techniques like electrospinning & corona charging


Prepare publications and presentations for wide range of audiences

Signal processing

Process and extract features from audio signals


Manage multiple collaborations; plan and organize events

Achievements & activities


Considerations and Challenges for Real-World Deployment of an Acoustic-Based COVID-19 Screening System. Sensors, 2022.

Optimized Acoustic Phantom Design for Characterizing Body Sound Sensors. Sensors, 2022.

Project-based learning through sensor characterization in a musical acoustics course. JASA, 2022.

Soft CNT-Polymer Composites for High Pressure Sensors. Sensors, 2022.

DNA increases the beta-phase content of PVDF films. CEIDP, 2020.

Electronic stethoscope filtering mimics the perceived sound characteristics of acoustic stethoscope. JBHI, 2020.

Neuromorphic self-driving robot with retinomorphic vision and spike-based processing/closed-loop control. CISS, 2017.

Honors & awards

Johns Hopkins Discovery Award 2022

Acoustical Society of America, DC Chapter, Oral Presentation Award

Collegiate Inventors Competition Runner Up Award

Johns Hopkins Discovery Award 2019

IEEE Dielectrics and Electrical Insulation Society Graduate Student Fellowship

Maryland State Three Minute Thesis Competition, Audience’s Choice

Johns Hopkins University Three Minute Thesis Competition, 2nd Place

Barry Goldwater Scholarship Honorable Mention

NOAA Hollings Scholar


Sonavi Labs research intern

Adjunct lecturer at Peabody Institute

Lab technician at Dipole Materials

Johns Hopkins HEART course instructor

Johns Hopkins Teaching Academy participant

Applied Research in Acoustics intern


Electrical and Computer Engineering Graduate Student Association President

Revision editor

Womxn Mentoring Whiting mentor

STEM Achievement in Baltimore Elementary Schools (SABES) program mentor


ASA Acoustics in Focus

Acoustics Virtually Everywhere

Conference on Electrical Insulation and Dielectric Phenomena

Materials Research Society


JMP Discovery Summit


Ocean Sciences Meeting

Side projects

Music, laser cutting, data visualization

E-mail vrennoll@gmail.com with questions

Cover photo credit: Will Kirk

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