skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Hydrogel-Fractal Piezoelectric Bilayer Transducer for Wireless Biochemical Sensing
This paper reports on a novel transducer for wireless biochemical sensing. The bilayer transducer consists of a fractal piezoelectric membrane and pH-sensitive chemo-mechanical hydrogel, which overcomes many shortcomings in the chemical and biochemical sensing. The fractal design on the piezoelectric membrane enhances frequency response and linearity by employing periodically repeated pore architecture. As a basis of the pore, a Hilbert space-filling curve with modifications is used. On the surface of the fractal piezoelectric membrane, the hydrogel is laminated. When the bilayer transducer is introduced to a pH environment (e.g., pH = 4, 8, and 12), the hydrogel swells (or shrinks) and induces the curling of the bilayer transducer (10.47°/pH). The curvature then exhibits various ultrasound responses when the bilayer transducer was excited. The measured voltage outputs using an ultrasonic receiver were 0.393, 0.341, 0.250 mV/cm 2 when curvature angles were 30°, 60°, and 120°, respectively. Overall pH sensitivity was 0.017 mV/cm 2 /pH. Ultimately, the biochemical sensing principle using a novel bilayer ultrasound transducer suggests a simple, low-cost, battery-less, and long-range wireless readout system as compared to traditional biochemical sensing.  more » « less
Award ID(s):
2029077
PAR ID:
10324530
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC)
Page Range / eLocation ID:
4089 to 4092
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; (, Frontiers in Bioengineering and Biotechnology)
    null (Ed.)
    Wireless monitoring of the physio-biochemical information is becoming increasingly important for healthcare. In this work, we present a proof-of-concept hydrogel-based wireless biochemical sensing scheme utilizing ultrasound. The sensing system utilizes silica-nanoparticle embedded hydrogel deposited on a thin glass substrate, which presents two prominent interfaces for ultrasonic backscattering (tissue/glass and hydrogel/glass). To overcome the effect of the varying acoustic properties of the intervening biological tissues between the sensor and the external transducer, we implemented a differential mode of ultrasonic back-scattering. Here, we demonstrate a wireless pH measurement with a resolution of 0.2 pH level change and a wireless sensing range around 10 cm in a water tank. 
    more » « less
  2. ; ; ; ; ; (, 2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC))
    In this work, we present a proof-of-concept hydrogel-based sensor system capable of wireless biochemical sensing through measuring backscattered ultrasound. The system consists of silica-nanoparticle embedded hydrogel deposited on a thin glass substrate, presenting two interfaces for backscattering (tissue/hydrogel and hydrogel/glass), which allows for system output to be invariant under the change in acoustic properties (e.g. attenuation, reflection) of the intervening biological tissue. We characterize the effect of silica nanoparticles (acoustic contrast agents) loading on the hydrogel's swelling ratio and its ultrasonic backscattering properties. We demonstrate a wireless pH measurement using dual modes of interrogations, reflection ratio and time delay. The ultrasonic hydrogel pH sensor is demonstrated with a sensing resolution of 0.2 pH level change with a wireless sensing distance around 10 cm. 
    more » « less
  3. ; ; ; ; ; (, 2021 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers))
    Continuous monitoring of biochemical information is critical for health management. Hydrogel, a synthetic material that exhibits volumetric response to target stimuli, is an attractive material for such applications. However, wireless readout of the hydrogel's response over a longer distance, while maintaining the small sensor dimension has been challenging. In this work we present ferrogel-based wireless acousto-biochemical sensing system with small dimension (length: 7.5 mm, diameter: 2 mm) and long sensing distance (>10 cm). The sensor utilizes ferromagnetic hydrogel to convert pH to the change in resonance frequency; the wireless measurement is made through the RF signal emission under ultrasonic excitation. 
    more » « less
  4. ; ; ; (, IEEE Sensors Letters)
    Ultrasound has been extensively used and investigated in medical applications, such as medical imaging [1] and drug delivery [2], because of advantages such as noninvasiveness, good penetration, good sensitivity, and ease of use. Prior to the development of piezoelectric micromachined ultrasound transducers (pMUTs), conventional transducers were made of piezoelectric ceramics, such as lead zirconate titanate [3]. These materials when operated in thickness mode exhibit a large impedance mismatch between the transducer surface and medium resulting in lower bandwidth unless augmented with one or more matching layers. With the development of MEMS technology, improvements in MUTs have been realized in several aspects, such as wide bandwidth without the addition of matching layers [4], smaller cell size, therefore higher operating frequency and better resolution, and easier fabrication of large arrays at lower cost [5]. Despite lower electromechanical coupling coefficient, the low-power consumption feature makes pMUTs good candidates for a variety of applications, including intrabody communication [6] and fingerprint sensing [7]. 
    more » « less
  5. ; ; ; ; ; ; (, Science of Sintering)
    Polyvinylidene fluoride (PVDF) is a novel gel polymer electrolyte alternative which can reduce the risk of irreversible failure in lithium-ion batteries (LIB) [1]. PVDF matrix structures which exhibit inter-crosslinking networks have previously demonstrated favorable thermal and mechanical properties for LIB applications [2]. PVDF based multifunctional material is attracting a great scientific interest due to its excellent piezoelectric, pyroelectric and ferroelectric properties. Such as, its properties strongly depend on synthesis procedures and obtained microstructures. In this research, porous structure and cross-linking patterns of PVDF were prepared by electrospinning method and it has been found that these microstructures can have fractal structure. Fractal analysis can be used as a powerful tool for describing structural and functional properties of these this material. Because of that, in this research we have used different fractal methods for the reconstructions of various PVDF microstructure morphologies. Fractal analysis has been performed by using scanning electron microscope micrographs and computational modeling tools. Theory of Iterated Function Systems and Voronoi tessellation, have been used for modeling PVDF porous structures. A Python algorithm was created to determine the distribution of pore areas in SEM micrographs. Algorithm?s distribution of calculated pore surface areas were compared with measured pore surface areas and fractal reconstructions of different morphologies and their connection with functional properties were analyzed. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email