Chemical Vapor Deposition
Chemical vapor deposition is a nascent, single-step processing method for forming electronic polymer films on unconventional substrates and is increasingly important for creating flexible and wearable electronics. A suite of vapor-phase polymerization reactions performed inside reduced-pressure hot wall reactors, collectively termed CVD, are the enabling methods we use to build novel devices.
CVD can be interpreted as a solvent-free synthetic technique, where multiple reagents converge in the vapor phase to effect a polymerization reaction. In CVD, polymer films are formed directly on the substrate of interest as vapors of a chemical agent and precursor (or monomer) are introduced into an evacuated reactor chamber simultaneously. This method allows for conformal coating of rough surfaces, with features resolvable down to 100-200 nm. The modularity of CVD ensures that careful monomer choice will lead to the in situ film growth of a host of functional polymers displaying varied properties.
Dr. Andrew's Research
2018
Zhang, Lushuai; Andrew, Trisha
Vapor-Coated Monofilament Fibers for Embroidered Electrochemical Transistor Arrays on Fabrics Journal Article
In: Advanced Electronic Materials, vol. 4, no. 9, pp. 1800271, 2018.
@article{zhang2018vapor,
title = {Vapor-Coated Monofilament Fibers for Embroidered Electrochemical Transistor Arrays on Fabrics},
author = {Lushuai Zhang and Trisha Andrew},
year = {2018},
date = {2018-01-01},
urldate = {2018-01-01},
journal = {Advanced Electronic Materials},
volume = {4},
number = {9},
pages = {1800271},
publisher = {Wiley Online Library},
abstract = {Fiber-based electrochemical transistors can be embroidered onto fabrics for wearable and implantable bioelectronics. However, the active channel length of known fiber-based electrochemical transistors is defined by the dynamic contact area between the conductive fiber and a liquid electrolyte, meaning that existing iterations cannot be reliably operated upon immersion in biological media. A proof-of-concept parallel-junction electrochemical transistor on a silk fabric with a fixed, micrometer-sized channel length that is independent of electrolyte contact area is reported. A high on/off ratio of 1000, and notable transconductance value of 100 µS at zero gate voltage and low applied drain bias (0.7 V) is obtained, making this device amenable to subsequent incorporation into low-power-consuming integrated circuits. Large-area arrays of this transistor can be rapidly created by straight-stitching a monofilament fiber channel onto a fabric substrate, meaning that simple embroidery approaches can be used to fabricate spatially resolved electrode arrays for electrophysiological applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Fiber-based electrochemical transistors can be embroidered onto fabrics for wearable and implantable bioelectronics. However, the active channel length of known fiber-based electrochemical transistors is defined by the dynamic contact area between the conductive fiber and a liquid electrolyte, meaning that existing iterations cannot be reliably operated upon immersion in biological media. A proof-of-concept parallel-junction electrochemical transistor on a silk fabric with a fixed, micrometer-sized channel length that is independent of electrolyte contact area is reported. A high on/off ratio of 1000, and notable transconductance value of 100 µS at zero gate voltage and low applied drain bias (0.7 V) is obtained, making this device amenable to subsequent incorporation into low-power-consuming integrated circuits. Large-area arrays of this transistor can be rapidly created by straight-stitching a monofilament fiber channel onto a fabric substrate, meaning that simple embroidery approaches can be used to fabricate spatially resolved electrode arrays for electrophysiological applications.
2017
Zhang, Lushuai; Baima, Morgan; Andrew, Trisha L
Transforming commercial textiles and threads into sewable and weavable electric heaters Journal Article
In: ACS applied materials & interfaces, vol. 9, no. 37, pp. 32299–32307, 2017.
@article{zhang2017transforming,
title = {Transforming commercial textiles and threads into sewable and weavable electric heaters},
author = {Lushuai Zhang and Morgan Baima and Trisha L Andrew},
year = {2017},
date = {2017-01-01},
urldate = {2017-01-01},
journal = {ACS applied materials & interfaces},
volume = {9},
number = {37},
pages = {32299--32307},
publisher = {ACS Publications},
abstract = {We describe a process to transform commercial textiles and threads into electric heaters that can be cut/sewn or woven to fashion lightweight fabric heaters for local climate control and personal thermal management. Off-the-shelf fabrics are coated with a 1.5 μm thick film of a conducting polymer, poly(3,4-ethylenedioxythiophene), using an improved reactive vapor deposition method. Changes in the hand feel, weight, and breathability of the textiles after the coating process are imperceptible. The resulting fabric electrodes possess competitively low sheet resistances—44 Ω/□ measured for coated bast fiber textiles and 61 Ω/□ measured for coated cotton textiles—and act as low-power-consuming Joule heating elements. The electrothermal response of the textile electrodes remain unaffected after cutting and sewing due to the robustness of the conductive coating. Coated, conductive cotton yarns can also be plain-woven into a monolithic fabric heater. A demonstrative circuit design for a soft, lightweight, and breathable thermal glove is provided.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We describe a process to transform commercial textiles and threads into electric heaters that can be cut/sewn or woven to fashion lightweight fabric heaters for local climate control and personal thermal management. Off-the-shelf fabrics are coated with a 1.5 μm thick film of a conducting polymer, poly(3,4-ethylenedioxythiophene), using an improved reactive vapor deposition method. Changes in the hand feel, weight, and breathability of the textiles after the coating process are imperceptible. The resulting fabric electrodes possess competitively low sheet resistances—44 Ω/□ measured for coated bast fiber textiles and 61 Ω/□ measured for coated cotton textiles—and act as low-power-consuming Joule heating elements. The electrothermal response of the textile electrodes remain unaffected after cutting and sewing due to the robustness of the conductive coating. Coated, conductive cotton yarns can also be plain-woven into a monolithic fabric heater. A demonstrative circuit design for a soft, lightweight, and breathable thermal glove is provided.
Allison, Linden; Hoxie, Steven; Andrew, Trisha L
Towards seamlessly-integrated textile electronics: methods to coat fabrics and fibers with conducting polymers for electronic applications Journal Article
In: Chemical Communications, vol. 53, no. 53, pp. 7182–7193, 2017.
@article{allison2017towards,
title = {Towards seamlessly-integrated textile electronics: methods to coat fabrics and fibers with conducting polymers for electronic applications},
author = {Linden Allison and Steven Hoxie and Trisha L Andrew},
year = {2017},
date = {2017-01-01},
urldate = {2017-01-01},
journal = {Chemical Communications},
volume = {53},
number = {53},
pages = {7182--7193},
publisher = {Royal Society of Chemistry},
abstract = {Traditional textile materials can be transformed into functional electronic components upon being dyed or coated with films of intrinsically conducting polymers, such as poly(aniline), poly(pyrrole) and poly(3,4-ethylenedioxythiophene). A variety of textile electronic devices are built from the conductive fibers and fabrics thus obtained, including: physiochemical sensors, thermoelectric fibers/fabrics, heated garments, artificial muscles and textile supercapacitors. In all these cases, electrical performance and device ruggedness is determined by the morphology of the conducting polymer active layer on the fiber or fabric substrate. Tremendous variation in active layer morphology can be observed with different coating or dyeing conditions. Here, we summarize various methods used to create fiber- and fabric-based devices and highlight the influence of the coating method on active layer morphology and device stability.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Traditional textile materials can be transformed into functional electronic components upon being dyed or coated with films of intrinsically conducting polymers, such as poly(aniline), poly(pyrrole) and poly(3,4-ethylenedioxythiophene). A variety of textile electronic devices are built from the conductive fibers and fabrics thus obtained, including: physiochemical sensors, thermoelectric fibers/fabrics, heated garments, artificial muscles and textile supercapacitors. In all these cases, electrical performance and device ruggedness is determined by the morphology of the conducting polymer active layer on the fiber or fabric substrate. Tremendous variation in active layer morphology can be observed with different coating or dyeing conditions. Here, we summarize various methods used to create fiber- and fabric-based devices and highlight the influence of the coating method on active layer morphology and device stability.
Zhang, Lushuai; Fairbanks, Marianne; Andrew, Trisha L
Rugged textile electrodes for wearable devices obtained by vapor coating off-the-shelf, plain-woven fabrics Journal Article
In: Advanced Functional Materials, vol. 27, no. 24, pp. 1700415, 2017.
@article{zhang2017rugged,
title = {Rugged textile electrodes for wearable devices obtained by vapor coating off-the-shelf, plain-woven fabrics},
author = {Lushuai Zhang and Marianne Fairbanks and Trisha L Andrew},
year = {2017},
date = {2017-01-01},
urldate = {2017-01-01},
journal = {Advanced Functional Materials},
volume = {27},
number = {24},
pages = {1700415},
publisher = {Wiley Online Library},
abstract = {Fabrics are pliable, breathable, lightweight, ambient stable, and have unmatched haptic perception. Here, a vapor deposition method is used to transform off-the-shelf plain-woven fabrics, such as linen, silk, and bast fiber fabrics, into metal-free conducting electrodes. These fabric electrodes are resistant to wear, stable after laundering and ironing, and can be body-mounted with little detriment to their performance. A unique by-product of conformally vapor coating plain-woven fabrics is that textile parameters, such as thread material and fabric porosity, significantly affect the conductivity of the resulting fabric electrodes. The resistivities of the electrodes reported herein are linearly, not exponentially, dependent on length, meaning that they can be feasibly incorporated into garments and other large-area body-mounted devices. Further, these fabric electrodes possess the feel, weight, breathability, and pliability of standard fabrics, which are important to enable adoption of wearable devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Fabrics are pliable, breathable, lightweight, ambient stable, and have unmatched haptic perception. Here, a vapor deposition method is used to transform off-the-shelf plain-woven fabrics, such as linen, silk, and bast fiber fabrics, into metal-free conducting electrodes. These fabric electrodes are resistant to wear, stable after laundering and ironing, and can be body-mounted with little detriment to their performance. A unique by-product of conformally vapor coating plain-woven fabrics is that textile parameters, such as thread material and fabric porosity, significantly affect the conductivity of the resulting fabric electrodes. The resistivities of the electrodes reported herein are linearly, not exponentially, dependent on length, meaning that they can be feasibly incorporated into garments and other large-area body-mounted devices. Further, these fabric electrodes possess the feel, weight, breathability, and pliability of standard fabrics, which are important to enable adoption of wearable devices.
2016
Zhang, Lushuai; Yu, Yanhao; Eyer, Gregory P; Suo, Guoquan; Kozik, Liz Anna; Fairbanks, Marianne; Wang, Xudong; Andrew, Trisha L
All-textile triboelectric generator compatible with traditional textile process Journal Article
In: Advanced Materials Technologies, vol. 1, no. 9, pp. 1600147, 2016.
@article{zhang2016all,
title = {All-textile triboelectric generator compatible with traditional textile process},
author = {Lushuai Zhang and Yanhao Yu and Gregory P Eyer and Guoquan Suo and Liz Anna Kozik and Marianne Fairbanks and Xudong Wang and Trisha L Andrew},
year = {2016},
date = {2016-01-01},
urldate = {2016-01-01},
journal = {Advanced Materials Technologies},
volume = {1},
number = {9},
pages = {1600147},
publisher = {Wiley Online Library},
abstract = {All-textile triboelectric generators (TEGs) allow for seamless integration of TEGs into garments, while maintaining the intrinsic flexibility, breathability, durability, and aesthetic value of normal textiles. However, practical approaches to construct fabric TEGs using traditional textile processes, such as sewing, weaving, and knitting, are underreported. In this work, two approaches to create an all-textile TEG using straight-forward textile manufacturing methods are presented. The first approach is to assemble two different cloths of opposite surface charge characteristics in a face-to-face configuration. A cotton fabric functionalized with fluoroalkylated polymeric siloxanes is necessary to generate usable triboelectric power output, when coupled with a pristine nylon cloth. The increased surface charge density by introducing fluoroalkyl groups is confirmed by Kelvin probe force microscopy measurements. The second approach is to weave or knit together two different conductive threads of opposite surface charge characteristics to create a monolithic triboelectric textile. The weave or knit pattern used to assemble this textile directly controls the density of contact points between the two types of threads, which, ultimately, determines the areal triboelectric power output of the textile. Overall, two feasible methods for constructing unprecedented textile-based triboelectric generators with notable power output are presented.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
All-textile triboelectric generators (TEGs) allow for seamless integration of TEGs into garments, while maintaining the intrinsic flexibility, breathability, durability, and aesthetic value of normal textiles. However, practical approaches to construct fabric TEGs using traditional textile processes, such as sewing, weaving, and knitting, are underreported. In this work, two approaches to create an all-textile TEG using straight-forward textile manufacturing methods are presented. The first approach is to assemble two different cloths of opposite surface charge characteristics in a face-to-face configuration. A cotton fabric functionalized with fluoroalkylated polymeric siloxanes is necessary to generate usable triboelectric power output, when coupled with a pristine nylon cloth. The increased surface charge density by introducing fluoroalkyl groups is confirmed by Kelvin probe force microscopy measurements. The second approach is to weave or knit together two different conductive threads of opposite surface charge characteristics to create a monolithic triboelectric textile. The weave or knit pattern used to assemble this textile directly controls the density of contact points between the two types of threads, which, ultimately, determines the areal triboelectric power output of the textile. Overall, two feasible methods for constructing unprecedented textile-based triboelectric generators with notable power output are presented.