Haptic apparatus for stimulating users' skin
A haptic apparatus is provided for stimulating a skin of a user to provide haptic feedback to the user. The haptic apparatus comprises an elastomeric substrate layer and multilayered electrical circuits comprising hydrogel electrodes for contacting the skin and electro-stimulating the skin to generate the haptic feedback. The multilayered electrical circuits are arranged on the elastomeric substrate layer, thereby avoiding forming the multilayered electrical circuits on a printed circuit board.
1 . A haptic apparatus for stimulating a skin of a user to provide haptic feedback to the user, the haptic apparatus comprising:
an elastomeric substrate layer; and
multilayered electrical circuits comprising hydrogel electrodes for contacting the skin and electro-stimulating the skin to generate the haptic feedback,
wherein the multilayered electrical circuits are arranged on the elastomeric substrate layer, thereby avoiding forming the multilayered electrical circuits on a printed circuit board.
2 . The haptic apparatus of claim 1 , wherein the multilayered electrical circuits are monolithically formed on the elastomeric substrate layer.
3 . The haptic apparatus of claim 1 , wherein the elastomeric substrate layer comprises an elastomeric fiber mat.
4 . The haptic apparatus of claim 1 , wherein the multilayered electrical circuits comprise patterned liquid metal (LM) traces.
5 . The haptic apparatus of claim 4 , wherein the hydrogel electrodes comprise:
LM pads disposed on the patterned LM traces; and
a bioadhesive hydrogel disposed on the LM pads for establishing an electrically conducive path to the skin.
6 . The haptic apparatus of claim 5 , wherein the hydrogel electrodes further comprise a paste mask layer sandwiched between the LM pads and the bioadhesive hydrogel, and the paste mask layer is configured to allow the bioadhesive hydrogel to penetrate at least partially through the paste mask layer, thereby contacting the LM pads.
7 . The haptic apparatus of claim 6 , wherein the paste mask layer comprises fiber mat.
8 . The haptic apparatus of claim 1 , wherein the multilayered electrical circuits comprise:
a first circuit layer comprising first patterned liquid metal (LM) traces;
a second circuit layer comprising second patterned LM traces; and
LM interconnects for electrically connecting the first circuit layer and the second circuit layer.
9 . The haptic apparatus of claim 8 , wherein the LM interconnects comprise vertical interconnect accesses (VIAs), and the VIAs comprise fluidic LM for electrically contacting both the first patterned LM traces and the second patterned LM traces.
10 . The haptic apparatus of claim 8 , wherein the multilayered electrical circuits comprise electronic components disposed on the second circuit layer, and the electronic components electrically contact the second patterned LM traces through hybrid LM (hLM) solders.
11 . The haptic apparatus of claim 10 , wherein the hLM solders comprise:
fluidic LM electrically contacting the electronic components; and
an oxidized LM (oLM) paste sandwiched between the fluidic LM and the second patterned LM traces, thereby to electrically connect the electronic components to the second circuit layer.
12 . The haptic apparatus of claim 1 , further comprising an elastomeric encapsulation layer for at least partially encapsulating the multilayered electrical circuits.
13 . The haptic apparatus of claim 12 , wherein the elastomeric encapsulation layer comprises an elastomeric fiber mat.
14 . The haptic apparatus of claim 1 , wherein the hydrogel electrodes comprise a plurality of channels, and the multilayered electrical circuits comprise a control circuit for generating pulsed voltage signals for feeding into the plurality of channels for stimulating the skin of the user.
15 . The haptic apparatus of claim 14 , wherein the control circuit comprises:
a power management module for generating a regulated voltage;
a voltage booster module for boosting up the regulated voltage to yield a boosted voltage;
a plurality of multiplexers for controllably switching on and off the boosted voltage to generate pulsed voltage signals; and
a microcontroller unit (MCU) configured to at least control the plurality of multiplexers in switching the boosted voltage for generating an individual pulsed voltage signal with a desired pulse frequency and a desired duty cycle.
16 . The haptic apparatus of claim 15 , wherein the power management module comprises:
a battery for providing a battery supplied electrical voltage; and
a regulator for regulating the battery supplied electrical voltage to the regulated voltage.
17 . The haptic apparatus of claim 16 , wherein the battery is a rechargeable battery, and the power management module further comprises a QI wireless charging module for recharging the rechargeable battery.
18 . The haptic apparatus of claim 15 , wherein the control circuit further comprises a current control module controllable by the MCU for monitoring and limiting a return current received by a common electrode from the user to avoid the user from getting an electric shock.
19 . The haptic apparatus of claim 18 , wherein the current control module comprises a current mirror that electrically connects to the MCU through either an operational amplifier or a digital-to-analog converter.
20 . The haptic apparatus of claim 1 , wherein the hydrogel electrodes have a highest electrode density of 2.26 units/cm 2 .