Method of manufacturing a fluidic tactile sensor
A method of manufacturing a fluidic tactile sensor includes forming a mold insert having an insoluble sensor core and a soluble skin insert attached to an outer surface of the sensor core. An elastic skin is molded over the mold insert to form a sensor preform in which the skin insert is encapsulated between the elastic skin and the sensor core. The skin insert is removed from between the elastic skin and the sensor core, at least partly by dissolving the skin insert in a solvent, to form a sensor body having one or more cells between the elastic skin and the sensor core. A pressure sensing circuit is attached to the sensor core of the sensor body.
1 . A method of manufacturing a fluidic tactile sensor, the method comprising:
forming a mold insert comprising a sensor core and a skin insert attached to an outer surface of the sensor core, wherein the skin insert is at least partially soluble in a solvent and the sensor core is insoluble in the solvent;
molding an elastic skin over the mold insert to form a sensor preform with the skin insert encapsulated between the elastic skin and the sensor core;
removing the skin insert from between the elastic skin and the sensor core to form a sensor body with one or more cells between the elastic skin and the sensor core, wherein the skin insert is removed at least in part by applying the solvent to the skin insert to at least partially dissolve the skin insert; and
attaching a pressure sensing circuit to the sensor core of the sensor body.
2 . The method of claim 1 , wherein the sensor core comprises an inner surface defining a chamber within the sensor core, wherein the chamber is connected to the outer surface of the sensor core by at least one channel extending from the inner surface to the outer surface, and wherein removing the skin insert from between the elastic skin and the sensor core comprises exposing an opening of the at least one channel to the solvent.
3 . The method of claim 2 , wherein forming the mold insert further comprises forming a plug insert in the chamber, and wherein the sensor core, the plug insert, and the skin insert are formed using additive manufacturing.
4 . The method of claim 3 , further comprising removing the plug insert from the chamber contemporaneously with removing the skin insert from between the elastic skin and the sensor core, wherein the plug insert is at least partially soluble in the solvent, and wherein the plug insert is removed at least in part by applying the solvent to the plug insert to at least partially dissolve the plug insert.
5 . The method of claim 1 , wherein removing the skin insert from between the elastic skin and the sensor core comprises applying the solvent to the skin insert through at least one channel formed in the sensor core.
6 . The method of claim 5 , wherein applying the solvent to the skin insert through the at least one channel formed in the sensor core comprises disposing the sensor preform in a bath containing the solvent and agitating the bath.
7 . The method of claim 6 , further comprising agitating the bath at an ultrasonic frequency and adjusting the ultrasonic frequency responsively to an effective length of the at least one channel to increase a dissolution rate of the skin insert.
8 . The method of claim 5 , wherein applying the solvent to the skin insert through at least one channel formed in the sensor core comprises directing a fluid jet into the at least one channel.
9 . The method of claim 1 , further comprising, prior to molding the elastic skin over the mold insert to form the sensor preform, applying a chemical adhesion promoter to the sensor core to promote adhesion of the elastic skin to the sensor core at contact interfaces between the elastic skin and the sensor core.
10 . The method of claim 9 , wherein molding the elastic skin over the mold insert to form the sensor preform comprises loading the mold insert into a mold cavity of a vacuum injection mold and injecting an injection molding material into the mold cavity under vacuum.
11 . The method of claim 10 , wherein injecting the injection molding material into the mold cavity under vacuum comprises:
disposing the mold cavity in a first chamber; and
connecting the first chamber to a vacuum source while injecting the injection molding material into the mold cavity.
12 . The method of claim 11 , wherein injecting the injection molding material into the mold cavity under vacuum further comprises:
disposing the injection molding material in a second chamber; and
connecting the second chamber to atmospheric pressure while flowing the injection molding material from the second chamber into the mold cavity in the first chamber.
13 . The method of claim 10 , further comprising curing the injection molding material within the mold cavity.
14 . The method of claim 1 , wherein the sensor core comprises an inner surface defining a chamber and one or more channels extending between the inner surface and the outer surface, and wherein attaching the pressure sensing circuit to the sensor core of the sensor body comprises mounting a first portion of the pressure sensing circuit within the chamber such that the first portion of the pressure sensing circuit extends over openings of the one or more inner channels at the inner surface.
15 . The method of claim 14 , further comprising forming a seal between the first portion of the pressure sensing circuit and the inner surface of the sensor core.
16 . The method of claim 15 , wherein forming the seal between the first portion of the pressure sensing circuit and the inner surface of the sensor core comprises:
applying a potting material to the first portion of the pressure sensing circuit;
disposing the first portion of the pressure sensing circuit adjacent to the inner surface of the sensor core; and
applying pressure to the first portion of the pressure sensing circuit in a direction against the inner surface of the sensor core.
17 . The method of claim 16 , wherein applying the pressure to the first portion of the pressure sensing circuit comprises disposing a core insert within a volume formed by the first portion of the pressure sensing circuit within the chamber, wherein the core insert engages the first portion of the pressure sensing circuit and the inner surface of the sensor core to apply the pressure to the first portion of the pressure sensing circuit.
18 . The method of claim 17 , further comprising filling voids in the chamber with the potting material and curing the potting material.
19 . The method of claim 1 , wherein forming the mold insert comprising the sensor core and the skin insert attached to the outer surface of the sensor core comprises forming the mold insert using additive manufacturing.
20 . The method of claim 19 , wherein forming the mold insert comprising the sensor core and the skin insert attached to the outer surface of the sensor core comprises printing the sensor core using a water-insoluble polymer, printing the skin insert using a water-soluble polymer, and printing a plug insert inside a chamber of the sensor core using the water-soluble polymer.