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Lo Presti A, Montoya NA, Criscuolo V, Khan G, Khan U, Vecchione R, Falconi C. Fundamentals of Skin Bioimpedances. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2302127. [PMID: 37252818 DOI: 10.1002/adma.202302127] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/14/2023] [Indexed: 06/01/2023]
Abstract
The bioimpedances of tissues beyond the stratum corneum, which is the outermost layer of skin, contain crucial clinical information. Nevertheless, bioimpedance measurements of both the viable skin and the adipose tissue are not widely used, mainly because of the complex multilayered skin structure and the electrically insulating nature of the stratum corneum. Here, a theoretical framework is established for analyzing the impedances of multilayered tissues and, in particular, of skin. Then, strategies are determined for the system-level design of electrodes and electronics, which minimize 4-wire (or tetrapolar) measurement errors even in the presence of a top insulating tissue, thus enabling non-invasive characterizations of tissues beyond the stratum corneum. As an example, non-invasive measurements of bioimpedances of living tissues are demonstrated in the presence of parasitic impedances which are much (e.g., up to 350 times) higher than the bioimpedances of the living tissues beyond the stratum corneum, independently on extreme variations of the barrier (tape stripping) or of the skin-electrode contact impedances (sweat). The results can advance the development of bioimpedance systems for the characterization of viable skin and adipose tissues in several applications, including transdermal drug delivery and the assessment of skin cancer, obesity, dehydration, type 2 diabetes mellitus, cardiovascular risk, and multipotent adult stem cells.
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Affiliation(s)
- Andrea Lo Presti
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Roma, 00133, Italy
| | - Nerio Andrés Montoya
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Roma, 00133, Italy
- School of Physics, Universidad Nacional de Colombia, Medellín, A. A. 3840, Colombia
| | - Valeria Criscuolo
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Roma, 00133, Italy
- Center for Advanced Biomaterial for Health Care, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, Naples, 80125, Italy
- Faculty of Electrical Engineering and IT, RWTH Aachen, 52062, Aachen, Germany
- Institute for Biological Information Processing - Bioelectronics, IBI-3, Forschungszentrum Juelich, 52428, Aachen, Germany
| | - Gulaly Khan
- School of Electrical Engineering and Computer Science, National University of Sciences and Technology, Sector H-12, Islamabad, 44000, Pakistan
| | - Usman Khan
- School of Electrical Engineering and Computer Science, National University of Sciences and Technology, Sector H-12, Islamabad, 44000, Pakistan
| | - Raffaele Vecchione
- Center for Advanced Biomaterial for Health Care, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, Naples, 80125, Italy
| | - Christian Falconi
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Roma, 00133, Italy
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Montoya NA, Criscuolo V, Lo Presti A, Vecchione R, Falconi C. Twin-Wire Networks for Zero Interconnect, High-Density 4-Wire Electrical Characterizations of Materials. RESEARCH (WASHINGTON, D.C.) 2022; 2022:9874249. [PMID: 35098140 PMCID: PMC8771198 DOI: 10.34133/2022/9874249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/05/2021] [Indexed: 02/04/2023]
Abstract
Four-wire measurements have been introduced by Lord Kelvin in 1861 and have since become the standard technique for characterizing small resistances and impedances. However, high-density 4-wire measurements are generally complex, time-consuming, and inefficient because of constraints on interconnects, pads, external wires, and mechanical contacts, thus reducing reproducibility, statistical significance, and throughput. Here, we introduce, systematically design, analyze, and experimentally validate zero interconnect networks interfaced to external instrumentation by couples of twin wire. 3D-printed holders with magnets, interconnects, nonadhesive layers, and spacers can effortlessly establish excellent electrical connections with tunable or minimum contact forces and enable accurate measurements even for delicate devices, such as thin metals on soft polymers. As an example, we measured all the resistances of a twin-wire 29-resistor network made of silver-nanoparticle ink printed on polyimide, paper, or photo paper, including during sintering or temperature calibration, resulting in an unprecedentedly easy and accurate characterization of both resistivity and its temperature coefficient. The theoretical framework and experimental strategies reported here represent a breakthrough toward zero interconnect, simple, and efficient high-density 4-wire characterizations, can be generalized to other 4-wire measurements (impedances, sensors) and can open the way to more statistically meaningful and reproducible analyses of materials, high-throughput measurements, and minimally invasive characterizations of biomaterials.
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Affiliation(s)
- Nerio Andrés Montoya
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Roma 00133, Italy.,School of Physics, Universidad Nacional de Colombia, A.A. 3840 Medellín, Colombia
| | - Valeria Criscuolo
- Center for Advanced Biomaterial for Health Care, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, Naples 80125, Italy
| | - Andrea Lo Presti
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Roma 00133, Italy
| | - Raffaele Vecchione
- Center for Advanced Biomaterial for Health Care, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, Naples 80125, Italy
| | - Christian Falconi
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Roma 00133, Italy
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