Multimodal, multilayered soft electronics in advanced devices and applications of same
An electronic system for multimodal diagnostic measurements and therapeutic interventions includes a plurality of element network layers vertically stacked one with another on a flexible substrate, each element network layer being bi-axially stretchable and comprising a plurality of elements configured in an addressable, interconnected array formed in a multilayered structure and operably performing a distinct function. The electronic system is a multimodal, multiplexed soft electronic system in a multilayered configuration that supports capabilities ranging from high-density spatiotemporal mapping of temperature, pressure and electrophysiological parameters, to options in programmable high-density actuation of thermal inputs and/or electrical stimulation, drug elution, radio frequency ablation, and/or irreversible electroporation ablation.
1 . An electronic system for multimodal diagnostic measurements and therapeutic interventions, comprising:
a plurality of element network layers vertically stacked one with another on a flexible substrate, each element network layer being bi-axially stretchable and comprising a plurality of elements configured in an addressable, interconnected array formed in a multilayered structure and operably performing a distinct function,
wherein the plurality of element network layers comprises:
an electrode array configured to perform electrophysiological recording and/or therapeutic interventions in a target of interest;
a temperature sensor array for precision thermography; and
a pressure sensor array for measuring forces or pressures associated with soft tissue contact in the target of interest;
wherein the pressure sensor array is disposed on the flexible substrate, the temperature sensor array is disposed on the pressure sensor array, and the electrode array is disposed on the temperature sensor array; and
wherein the pressure sensor array comprises a plurality of pressure sensors, each pressure sensor being formed of a metal strain gauge, wherein the metal strain gauge of each pressure sensor is in a form of a three-dimension (3D) tent-like mesostructure with high sensitivity to normal force and low effective modulus, wherein each 3D tent-like mesostructure is covered with a silicon cavity, and said cavity has lateral dimensions with a plurality of pillars at the corners, each pillar having a length and a height.
2 . The electronic system of claim 1 , wherein the flexible substrate is a balloon catheter or an elastic object that is operably in a deflated state or an inflated state.
3 . The electronic system of claim 1 , wherein the therapeutic interventions comprise electrical stimulation, radio frequency (RF) ablation, and/or irreversible electroporation (IRE) ablation.
4 . The electronic system of claim 2 , wherein the electrode array comprises a plurality of electrodes connected to stretchable interconnects and disposed between first and second polymer layers such that the plurality of electrodes is exposed.
5 . The electronic system of claim 4 , wherein the plurality of electrodes is individually and selectively controllable and/or programmable.
6 . The electronic system of claim 4 , wherein the exposed electrodes are in contact with the target of interest when the flexible substrate is operably in the inflated state.
7 . The electronic system of claim 4 , wherein each of the first and second polymer layers is formed of polyimides, polyurethane, polyethylene, and/or silicone.
8 . The electronic system of claim 7 , wherein each of the first and second polymer layers has a thickness of about 0.8-4 μm.
9 . The electronic system of claim 4 , wherein each electrode has a lateral dimension of about 400 μm×400 μm to 1 mm×1 mm, and a thickness of about 200 nm to 750 nm.
10 . The electronic system of claim 4 , wherein the plurality of electrodes and the stretchable interconnects are formed of a metal, or an alloy.
11 . The electronic system of claim 4 , wherein the stretchable interconnects are configured to accommodate bi-axial stretching greater than about 30% without inducing fractures in the electrode array.
12 . The electronic system of claim 11 , wherein each of the stretchable interconnects has a width of about 10-80 μm and is separated from one another by a width of about 10-100 μm of polyimides, polyurethane, polyethylene, and/or silicone.
13 . The electronic system of claim 1 , wherein the temperature sensor array comprises a plurality of temperature sensors, each temperature sensor being formed of metal traces, and electrically coupled to two temperature sensor connection lines that allow column and row selection multiplexing using signals delivered through the temperature sensor connection lines.
14 . The electronic system of claim 13 , wherein the metal traces are formed of a metal, or an alloy.
15 . The electronic system of claim 14 , wherein the metal traces are formed of gold, or a copper-nickel alloy.
16 . The electronic system of claim 13 , wherein each metal trace has a thickness of about 80-120 nm and a width of about 3-5 μm.
17 . The electronic system of claim 13 , wherein the temperature sensor connection lines for row selection reside in a first layer with the plurality of temperature sensors, while those for column selection lie a second layer above the first layer, separated by an insulating layer and connected to one side of the temperature sensors through a via hole.
18 . The electronic system of claim 17 , wherein the insulating layer is formed of polyimides, polyurethane, polyethylene, and/or silicone.
19 . The electronic system of claim 17 , wherein the insulating layer has a thickness in a range of about 1-10 μm.
20 . The electronic system of claim 13 , wherein averaged outputs from the plurality of temperature sensors yield a precision of one standard deviation ranging from about 10 mK to about 200 mK.
21 . The electronic system of claim 13 , wherein the temperature sensor array further comprises a layer of thermal actuators separated from the plurality of temperature sensors for spatial mapping of tissue thermal conductivity.
22 . The electronic system of claim 21 , wherein transient plane source analysis of the time-domain temperature profiles from the plurality of temperature sensors yields tissue thermal conductivities at different locations.
23 . The electronic system of claim 22 , wherein data acquired from the temperature sensor array are processed for assessment of parameters including flow of blood and other biofluids and tissue hydration levels.
24 . The electronic system of claim 1 , wherein each pressure sensor is electrically coupled to two pressure sensor connection lines that allow column and row selection multiplexing using signals delivered through the pressure sensor connection lines.
25 . The electronic system of claim 24 , wherein column and row selection occurs through serpentine interconnects across two different layers.
26 . The electronic system of claim 24 , wherein two terminals of each strain gauge are arranged in a cross-shaped geometry having a ribbon width and a ribbon length for facilitating wiring for the column and row selections.
27 . The electronic system of claim 26 , wherein each strain gauge and its two terminals are formed of a metal or an alloy.
28 . The electronic system of claim 26 , wherein each strain gauge has a thickness in a range of about 80-120 μm and a width in a range of about 1-3 μm, and wherein the ribbon width is in a range of about 100-150 μm, and the ribbon length is in a range of about 700-1100 μm.
29 . The electronic system of claim 25 , wherein the serpentine interconnects are in a form of 3D helices with exceptional stretchability.
30 . The electronic system of claim 1 , wherein the lateral dimensions of said cavity are in a range of about 0.5 mm by 0.5 mm to 1 mm by 1 mm, the length and the height of the pillars are in ranges of about 100-250 μm and about 150-200 μm, respectively.
31 . The electronic system of claim 1 , wherein sensitivity of each pressure sensor is tunable by adjusting side lengths of the pillars of said cavity, shapes of the 3D tent-like mesostructures, thicknesses of the polymer layers, and/or thickness and modulus of the flexible substrate.
32 . The electronic system of claim 29 , wherein the pressure sensor array further comprises rigid islands selectively bonded to the bottom surface of the pressure sensor array to constrain deformations of the 3D tent-like mesostructures under stretching, while maintaining stretchability of the pressure sensor array.
33 . The electronic system of claim 24 , wherein the pressure sensor array is insensitive to other types of mechanical deformations including bending and twisting.
34 . The electronic system of claim 1 , wherein the temperature sensor array is bonded to a bottom surface of the electrode array with a thin layer of polyimide (PI) to offer small thickness, strong adhesion and excellent thermal and physical contact for precise temperature measurements during ablation or other procedures.
35 . The electronic system of claim 34 , wherein the thin layer of PI has a thickness in a range of about 1-2 μm.
36 . The electronic system of claim 34 , wherein the pressure sensor array is located at the bottom of the plurality of element network layers for measurements of the local transverse forces at the interface between the electrodes and the contacting soft tissues.
37 . The electronic system of claim 36 , wherein the electrode array, the temperature sensor array and the pressure sensor array are vertically stacked to define a multilayer mesh having an array of sensing elements, each element comprising an electrode, a temperature sensor and a pressure sensor, and being connected to one another through the stretchable interconnects and connection lines that are untethered to the flexible substrate so as to enable out-of-plane deformations for enhanced stretchability.
38 . The electronic system of claim 37 , wherein the array of sensing elements is individually and selectively controllable and/or programmable.
39 . The electronic system of claim 4 , wherein in operation, the flexible substrate is in the inflated state, the exposed electrodes of the electrode array are in contact with target biological tissues to perform electrophysiological recording and/or therapeutic interventions, the temperature sensor array tracks changes in temperature associated with the therapeutic interventions; and the pressure sensor array measures local transverse forces at the interface between the electrodes and the biological tissues.
40 . The electronic system of claim 39 , wherein the measured temperature and pressure provide feedbacks for the therapeutic interventions in the target surface of interest.
41 . The electronic system of claim 4 , further comprising a multiplexed data acquisition (DAQ) system electrically coupled to the electrode array, wherein the DAQ comprises an application-specific integrated circuit (ASIC) configured to amplify, digitize and multiplex signals output from or input to the plurality of electrodes, thereby reducing a total number of wires connecting to an external instrument.
42 . The electronic system of claim 1 , further comprising a multiplexing circuit coupled to the temperature sensor array and/or the pressure sensor array for multiplexing of input and output signals of the plurality of temperature sensors and/or the plurality of pressure sensors and eliminating crosstalk with grounding.
43 . The electronic system of claim 1 , wherein the electronic system is conformally integrated with the flexible substrate.