Breathable and skin-conformal electronics with hybrid integration of microfabricated multifunctional sensors and kirigami-structured nanofibrous substrates

A method of making a breathable conformal electronic membrane (BCEM), the method comprising:

• fabricating a multiplicity of electronic components connected with or comprising stretchable serpentine patterns on a planar wafer having a planar surface area of less than 80 square centimeters;
• selectively encapsulating the electronic components with a polyimide (PI) layer configured and adapted to inhibit crosstalk between components or current leakage;
• placing a sacrificial layer based on poly(methyl methacrylate) (PMMA) between the electronic components and the planar substrate;
• releasing the electronic components from the planar wafer after dissolving PMMA in acetone;
• picking up the electronic components with a stamp comprising a water-soluble tape to create a device-on-stamp;
• and
• electrospinning polymer on the device-on-stamp to create a porous substrate having a desired flexibility and mass permeability.

A breathable conformal electronic membrane (BCEM), the BCEM comprising:

• a multiplicity of planar-fabricated electronic components arranged in a stretchable serpentine pattern and selectively encapsulated with at least one encapsulating layer;
• and
• a flexible, mass permeable, and porous substrate comprising electrospun polymer nanofibers bonded to the planar-fabricated electronic components, the encapsulating layer, or both;
• the porous substrate comprising a network of kirigami cuts configured and adapted to mitigate stress concentration during deformation while maintaining connectivity and structural integrity of the planar-fabricated electronic components;
• wherein the BCEM has a non-deformed configuration having a planar surface area of less than 80 square centimeters, and a deformed configuration having a planar surface area equal to or greater than about 200 square centimeters,
• wherein the BCEM in the non-deformed configuration has a water vapor transmission greater than 0.1 g/cm2 per day,
• wherein the planar-fabricated electronic components comprise a multiplicity of microfabricated sensors selected from the group consisting of bipolar electrodes, unipolar electrodes, temperature sensors, and hydration sensors;
• wherein the network of kirigami cuts is arranged in an offset array comprising a multiplicity of horizontal rows and a multiplicity of vertical columns, each row comprising a multiplicity of aligned horizontal cuts, each cut separated from respective adjacent cuts by a gap, wherein each respective row above a bottom row is offset such that a majority of gaps in each row are vertically aligned above a midpoint of a cut in the row below;
• wherein each respective cut comprises a common length of cut, Lc, each respective gap comprises a common gap length, x, and each respective row above a first row is separated from the row below by a common height, y;
• such that the array is a regular repeating array arranged such that each respective cut in each respective row above the first two rows is aligned with a respective cut in the second row below and each respective gap in each respective row above the first two rows is aligned with a respective gap in the second row below;
• wherein the values of Lc, x, and y, respectively are selected such that the ratio
• (
• L
• c
• -
• x
• )
• 2
• ⁢
• y
• is equal to or greater than 2;
• and
• wherein the planar-fabricated electronic components are configured, adapted, and aligned with respective kirigami cuts and respective gaps to produce deformation-invariant electrical performance with less than 10% change in resistance (ΔR/R0) as the BCEM is exposed to each of (1) stretching uniaxially from 0% to 120%, (2) twisting by 720°, and (3) loading with 10,000 cycles of 80% elongation.