Force sensor controlled conductive heating elements

Abstract

Described herein are methods for forming resistive heaters and force sensing elements on a flexible substrate, and devices that include these elements to provide a force responsive conductive heater, such as a seat heater in a vehicle. The methods include printing a conductive ink on a flexible substrate that is heated to 30° C. to 90° C. before and/or during the printing process and curing the substrate to produce a conductive pattern thereon. The conductive inks generally include a particle-free metal-complex composition formulated from at least one metal complex and a solvent, and optionally, a conductive filler material.

1 .- 19 . (canceled) 
     
     
         20 . A flexible resistive heater comprising:
 a flexible substrate having at least one conductive pattern printed thereon and configured to carry a current and generate heat,   wherein the at least one conductive pattern is printed with a conductive ink on the flexible substrate and comprises greater than 90% metal, and   wherein the flexible substrate is a flexible textile or polymer film,   wherein the conductive ink comprises a particle-free metal complex composition comprising:   at least one metal complex comprising:
 at least one metal,
 at least one first ligand that is a sigma donor to the metal and volatilizes upon heating the metal complex, and 
 at least one second ligand that is different from the first ligand and volatilizes upon heating the metal complex; and 
 
 a solvent, 
   wherein the metal complex has a solubility measured at 25° C. of at least 250 mg/ml in the solvent,   wherein the at least one metal, the at least one first ligand, and the at least one second ligand are provided in stoichiometric amounts in the conductive ink, and   wherein the conductive ink forms nanoparticles on the flexible substrate after curing to form the conductive pattern.   wherein the conductive ink further comprises at least one conductive filler material, wherein the at least one metal complex and the at least one conductive filler material are provided in the conductive ink in a ratio of metal complex to conductive filler material of 50:50 to 99:1,   wherein the at least one conductive filler material comprises one or more of a conductive polymer, a metal oxide, or a carbon-based material.   wherein the conductive ink comprises:
 10-40 wt. % of the conductive filler material and the metal complex provided in a ratio of metal complex to conductive filler material of 50:50 to 99:1; 
 2-10 wt. % of an alcohol or amine; 
 2-15 wt. % of glycol; 
 10-25 wt. % of a conductive filler solubilizer; and 
 40-70 wt. % of water. 
   
     
     
         21 . The resistive heater according to  claim 20 , further comprising at least one bus printed with the conductive ink, the at least one bus electrically connected to the at least one conductive pattern and configured to provide connection to a heater controller and a power source. 
     
     
         22 . The resistive heater according to  claim 20 , wherein the flexible textile comprises a knit, woven, or nonwoven fabric comprising fibers of polyester, polyamides, spandex, nylon, Evolon®, elastane, cotton, cellulose, silk, wood, wool, leather, or blends thereof, and wherein the polymer film comprises a polyimide, polyethylene terephthalate, polyethersulfone, polyetheretherketone, polyamide, or polyamideimide film. 
     
     
         23 .- 30  (canceled) 
     
     
         31 . A flexible force sensor comprising:
 an electrode layer comprising at least one electrode printed on a first flexible substrate with a conductive ink; and   a conductive layer on a second flexible substrate that is separated from the electrode layer by a gap having a separation distance,   wherein the flexible force sensor is configured to initiate an electrical signal upon compression of the electrode layer and conductive layer in a direction perpendicular to a longitudinal extent of the force sensor,   wherein the electrode layer comprises at least two electrodes printed on a first side of the flexible substrate, and   wherein the conductive layer comprises an electrically conductive strip on a first side of a second flexible substrate, wherein the conductive strip of the conductive layer faces the at least two electrodes of the electrode layer.   
     
     
         32 . The force sensor of  claim 31 , further comprising a control circuitry connected to the at least one electrode, a transceiver, and a controller, wherein the control circuitry is configured to carry the electrical signal to the transceiver and communicate a registered force or change in resistance to the controller. 
     
     
         33 .- 34 . (canceled) 
     
     
         35 . The force sensor according to  claim 31 , wherein the gap is maintained by a mesh fabric, embossing on one of the substrate layers, a material frame, such as a polymer film comprising an opening in the region of the electrode, dots or beads, or any combination thereof. 
     
     
         36 . The force sensor of  claim 31 , wherein the separation distance is at least 10 microns, such as at least 20 microns, or at least 40 microns, or at least 60 microns, or at least 100 microns. 
     
     
         37 . The force sensor according to  claim 31 , wherein the electrode layer and the conductive layer are bonded by a hot melt bonding film, pressure sensitive bonding film, pressure sensitive adhesive, or by sewing outside of the region comprising the first and second electrodes. 
     
     
         38 . The force sensor according to  claim 31 , wherein the conductive ink comprises:
 a particle-free metal complex composition comprising:
 at least one metal complex comprising:
 at least one metal, 
 at least one first ligand that is a sigma donor to the metal and volatilizes upon heating the metal complex, and 
 at least one second ligand that is different from the first ligand and volatilizes upon heating the metal complex; and 
 
 a solvent, 
   wherein the metal complex has a solubility measured at 25° C. of at least 250 mg/ml in the solvent,   wherein the at least one metal, the at least one first ligand, and the at least one second ligand are provided in stoichiometric amounts in the conductive ink.   
     
     
         39 . The force sensor according to  claim 38 , wherein the conductive ink forms nanoparticles on the flexible substrate after curing to form the conductive pattern. 
     
     
         40 . The force sensor according to  claim 31 , wherein the conductive strip is printed with a conductive ink comprising a particle-free metal complex composition, a resistive carbon-based ink, a conductive paint, indium tin oxide (ITO), or a combination thereof, or may comprise any of a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a carbon nanotube-based thin film (CNT), a carbon-loaded thermoplastic polymer, carbon-loaded silicone, carbon-loaded polymeric foil, velostat, or any combination thereof. 
     
     
         41 .- 43 . (canceled) 
     
     
         44 . A force sensor controlled resistive heater comprising:
 a resistive heater comprising:
 a first flexible substrate having at least one conductive pattern printed thereon with a first conductive ink and configured to carry a current and generate heat, and 
 at least one bus printed with the conductive ink, the bus electrically connected to the at least one conductive pattern and configured to provide connection to a power source; 
   a force sensor comprising:
 an electrode layer having at least one electrode printed on a second flexible substrate with a second conductive ink and a conductive layer, wherein the electrode layer and the conductive layer are separated by a gap having a separation distance, 
 wherein the flexible force sensor is configured to initiate an electrical signal upon compression of the electrode layer and the conductive layer in a direction perpendicular to a longitudinal extent of the force sensor; and 
   a control circuitry connected to the at least one electrode of the force sensor and configured to carry the electrical signal from the force sensor to a controller,   wherein the controller device is configured to communicate with a heater controller to control supply of power from the power source to the resistive heater based at least in part on the electrical signal from the force sensor,   wherein the electrode layer of the force sensor comprises at least two electrodes printed on a first side of the flexible substrate, and   wherein the conductive layer of the force sensor comprises an electrically conductive strip on a first side of a third flexible substrate, wherein the conductive strip of the conductive layer faces the at least two electrodes of the electrode layer.   
     
     
         45 . The sensor-controlled heater according to  claim 44 , wherein at least a portion of the at least one conductive pattern of the resistive heater is over-coated with a protective dielectric coating. 
     
     
         46 .- 48 . (canceled) 
     
     
         49 . The sensor-controlled heater according to  claim 44 , wherein the conductive strip of the force sensor is printed with the first or second conductive ink, a resistive carbon-based ink, a conductive paint, indium tin oxide (ITO), or a combination thereof, or may comprise any of a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a carbon nanotube-based thin film (CNT), a carbon-loaded thermoplastic polymer, carbon-loaded silicone, carbon-loaded polymeric foil, velostat, or any combination thereof. 
     
     
         50 . (canceled) 
     
     
         51 . The sensor-controlled heater according to  claim 44 , wherein the gap is maintained by a mesh fabric, embossing on one of the substrate layers, a material frame, such as a polymer film comprising an opening in the region of the electrode, dots or beads, or any combination thereof. 
     
     
         52 .- 54 . (canceled) 
     
     
         55 . The sensor-controlled heater according to  claim 44 , wherein the first and second conductive inks comprise:
 a particle-free metal complex composition comprising:
 at least one metal complex comprising:
 at least one metal, 
 at least one first ligand that is a sigma donor to the metal and volatilizes upon heating the metal complex, and 
 at least one second ligand that is different from the first ligand and volatilizes upon heating the metal complex; and 
 
 a solvent, 
   wherein the metal complex has a solubility measured at 25° C. of at least 250 mg/ml in the solvent,   wherein the at least one metal, the at least one first ligand, and the at least one second ligand are provided in stoichiometric amounts in the conductive ink.   
     
     
         56 . The sensor-controlled heater according to  claim 44 , wherein the first and second conductive inks are particle-free prior to deposition and form nanoparticles after curing to form a conductive metal. 
     
     
         57 . The sensor-controlled heater according to  claim 55 , wherein the first conductive ink further comprises at least one conductive filler material, wherein the at least one metal complex and the at least one conductive filler material are provided in the conductive ink in a ratio of metal complex to conductive filler material of 50:50 to 99:1. 
     
     
         58 . The sensor-controlled heater according to  claim 55 , wherein the solvent of the second conductive ink comprises one or more polar protic solvents, wherein the one or more polar protic solvents comprise one or more of water, an alcohol, and an amine. 
     
     
         59 .- 62 . (canceled) 
     
     
         63 . The sensor-controlled heater of  claim 44 , wherein the first conductive ink comprises:
 10-40 wt. % of the conductive filler material and the metal complex provided in a ratio of metal complex to conductive filler material of 50:50 to 99:1;   2-10 wt. % of an alcohol or amine;   2-15 wt. % of glycol;   10-25 wt. % of a conductive filler solubilizer; and   40-70 wt. % of water.