High-resolution patterning and transferring of functional nanomaterials toward massive production of flexible, conformal, and wearable sensors of many kinds on adhesive tapes
Methods, systems, and apparatus for high-resolution patterning of various substrates with functional materials, including nanomaterials. A technique of preparing a patterned substrate in a high-resolution mold for stick and transfer process is disclosed with promotes integrity of the high-resolution pattern onto the substrate. One example of a substrate is an adhesive tape. The transferred pattern(s) are scalable and can be implemented in different fabrication processes. One example is a roll-to-roll processes. In one embodiment, the transferred pattern comprises nanomaterials and the substrate comprises a flexible substrate for use in flexible and conformal assemblies for a wide variety of applications including, but not limited to, electrical-based sensors on non-planar inanimate surfaces, plant body surface, or human or animal skin.
1. A method of manufacturing electronic sensors comprising:
a. creating a mold comprising a microscale or smaller negative pattern on a substrate;
b. producing a positive pattern containing functional nanomaterials in the negative pattern of the mold with a drop-cast-dry-stick-peel (D2SP) process comprising:
i. drop-casting a starting volume of a solution including functional nanomaterials onto the mold;
ii. drying the solution into a thin-film on the mold, including into the negative pattern and on non-patterned mold surfaces;
iii. applying a cleaning adhesive tape over the mold and peeling the cleaning tape off the mold, the cleaning tape having an adhesive and tape substrate with properties relative the mold substrate and thin layer of nanomaterials which is effective to remove or clean the non-patterned surfaces of the mold but leave the thin layer in the negative pattern of the mold at least substantially intact;
iv. repeating steps i. to iii. multiple times until the negative pattern of the mold has multiple intact layers of the same or different nanomaterials built up layer-by-layer in the negative pattern; and
c. transferring the intact positive pattern in the mold to a transfer or target adhesive tape with a stick-and-peel transfer (ST) technique comprising:
i. applying the target or transfer tape to the mold and peeling the target or transfer tape off the mold, the target or transfer tape having an adhesive and tape substrate with properties relative the mold substrate and positive pattern of nanomaterials which is effective to remove the positive pattern from the negative pattern of the mold at least substantially intact;
ii. so that the target or transfer tape with adhered positive nanomaterial pattern comprises a flexible, conformal electronic sensor ready for application to a sensing function.
2. The method of claim 1 further comprising non-destructively annealing all or selected parts of the transferred pattern in situ on the transfer tape during fabrication or at a point of use of the transfer tape for one or more of:
a. improving adhesion of the positive pattern to the transfer tape substrate; and
b. tuning the electrical properties of the nanomaterials.
3. The method of claim 1 wherein the mold comprises PDMS and the negative pattern comprises a microscale or smaller pattern.
4. The method of claim 1 wherein the functional nanomaterials comprise:
a. graphene;
b. graphene oxide,
c. nanotubes;
d. nanoparticles;
e. nanowires; or
f. molybdenum disulfide.
5. The method of claim 1 wherein the tape substrate of the target or transfer tape comprises:
a. polyimide tape;
b. pressure sensitive tape,
c. electrically conductive tape;
d. aluminum foil; or
e. vapor/gas exchange tape.
6. The method of claim 1 wherein the adhesive for the target or transfer tape comprises:
a. synthetic rubber;
b. silicone; or
c. acrylic.
7. The method of claim 1 wherein:
a. the adhesive and substrate for the cleaning tape is selected based on one or more of the following parameters:
i. the type of adhesive and its adhesive properties;
ii. the mold material and the cleaning tape to mold material adhesive interface;
iii. the thin film on the mold and the cleaning tape to thin film adhesive interface;
iv. the thickness and properties of the thin film;
v. the depth and width of the negative features of the mold;
vi. number of repeats of the D2SP to build up a desired thickness of layers of thin films to form the positive pattern; and
b. the adhesive and substrate for the transfer tape is selected based on one or more of the following parameters:
i. the type of adhesive and its adhesive properties;
ii. the mold material and the transfer tape to mold material adhesive interface;
iii. the thickness and properties of the positive pattern in the negative pattern of the mold to the transfer tape to positive pattern adhesive interface.
8. The method of claim 1 wherein the pattern comprises an electrical circuit.
9. The method of claim 8 wherein the electrical circuit comprises a sensor circuit.
10. The method of claim 1 wherein the transferred pattern is replicated plural times on the transfer tape so that a large-scale or roll-to-roll (R2R) fabrication of a multiplicity of patterns is created.
11. The method of claim 10 wherein the large scale or R2R multiplicity of patterns are used for tape-based flexible, conformable sensors comprising:
a. force sensors;
b. pressure sensors;
c. strain sensors;
d. motion sensors;
e. moisture sensors;
f. pesticide/nutrient sensors;
g. gas sensors;
h. volatile organic compound sensors; or
i. sweat sensors.