Katherine Song - Academia.edu (original) (raw)

Papers by Katherine Song

Proceedings of the 2023 CHI Conference on Human Factors in Computing Systems

The goal of our interface is to allow a general audience interested in food to explore how ingred... more The goal of our interface is to allow a general audience interested in food to explore how ingredients in dishes connect and distinguish different cuisines around the world and how they are used with each other. Insights that we expect our audience to be able to learn after interacting with our interface include what popular ingredients in different cuisines are, what cuisines are similar to each other, and how ingredients are used in conjunction with each other in a cross-cultural context.

ECS Meeting Abstracts, 2010

International Journal of Physical Medicine & Rehabilitation, 2016

Advancements in robotic technologies have enabled a significant improvement in the clinical effic... more Advancements in robotic technologies have enabled a significant improvement in the clinical efficacy of prosthetic limbs for persons with upper and lower-extremity amputations. However, significant challenges still remain in establishing a biomimetic bidirectional neural communication between amputees and their external powered prostheses. Regenerative peripheral nerve interfaces may offer a high-resolution alternative to conventional nerve interface technologies for their unique potential to provide increased biospatial resolution for both the control of and feedback from an external powered prosthesis. Here, we present three separate design for 3-D microchannel arrays, each having 16-20 channels measuring 200 μm by 200 μm: one passive (without integrated electrodes), one active (with integrated electrodes), and one active with a porous collagen scaffold. With the array positioned between proximal and distal nerve sendings, we evaluate their effectiveness in tibial n. regeneration in vivo in both rats (N=4) and ferrets (N=4). Using immunofluorescence, we report robust mixed sensory and motor nerve regeneration through the microchannels in all rats, and weak regeneration in 2 of 4 ferrets, suggesting both interspecies regeneration variability and the lack of benefit of axially oriented collagen in improving ferret nerve regeneration through microchannels.

Chairman, Department Committee on Graduate Students I am indebted to my advisor, Vladimir Bulović... more Chairman, Department Committee on Graduate Students I am indebted to my advisor, Vladimir Bulović, whose support and endless enthusiasm made this work possible and broadened my perspectives as a scientist. I am also grateful for the scientific and moral support from all the members of the Organic and Nanostructured Electronics Laboratory (ONE Lab). I would especially like to thank Yasuhiro Shirasaki and Geoffrey Supran, the group's resident quantum dot light emitting device experts, for patiently sharing their wisdom with me in the past 2 years, and Farnaz Niroui for always being there to help me sort through an endless jumble of ideas about research and life. Additional acknowledgements go to the MIT Henry Ford II Fellowship, the NSF Graduate Research Fellowship, and the DOE Center for Excitonics for generously funding my work. Finally, I am forever thankful for the many other wonderful people who helped me find my way (and survive) to where I am, including but not limited to my undergraduate research advisors, Sigurd Wagner and Naveen Verma, my mother, and everyone else who has ever made me think or laugh.

Physical Review B, 2011

Experimental and theoretical studies of the electronic structure of bulk heterojunction (BHJ) org... more Experimental and theoretical studies of the electronic structure of bulk heterojunction (BHJ) organic solar cells are reported. The photoconductivity spectral response of the solar cells has a weak absorption band extending from the band-gap energy down to <1 eV due to charge-transfer optical excitation at the interface between the polymer and the fullerene. The low-energy absorption indicates an exponential band tail of localized states and an absorption model based on the one-electron joint density of electronic states accounts for the data. Transient photoconductivity measurements of the carrier mobility exhibit a temperature-dependent carrier dispersion. Data analysis for the particular case of transport in the BHJ structure is developed. A multiple trapping model of the dispersive transport is consistent with localized band tail states having a comparable density-of-states distribution to those observed by optical absorption. Theoretical calculations of the density of states including disorder in the π-π spacing of the polymer chains also shows exponential band tailing. A density-of-states model is developed from the data and is discussed.

Organic Electronics, 2011

The series resistance of a bulk heterojunction solar cell diode affects the measurement of the vo... more The series resistance of a bulk heterojunction solar cell diode affects the measurement of the voltage dependence of the diode photocurrent, P(V). An empirical model for the effect is described and shows that P(V) can be significantly modified, particularly at high bias voltages. Experimental measurements on PCDTBT:PCBM solar cells with added series resistance demonstrate the effect and confirm the model. The model provides a method to correct the photoconductivity data using measured quantities.

International Journal of Hydrogen Energy, 2011

As a highly reactive gas, hydrogen presents significant challenges for its acquisition and safe s... more As a highly reactive gas, hydrogen presents significant challenges for its acquisition and safe storage. Consequently, the viability of a sustainable hydrogen economy greatly depends on the development of an efficient, cost-effective method of hydrogen production. One model for addressing this challenge is to deploy portable hydrogen generators for the home. The Princeton University Chapter of the International Association for Hydrogen Energy (IAHE-PU) has designed and created a generator that produces hydrogen through water electrolysis and optimizes cost effectiveness and portability while maximizing hydrogen output. For our proof-of-concept, the system utilizes simple household items with a Sharp ND130UJF 130W solar panel. In our design, Ni electrodes submerged in 8 M KOH solution in six glass containers were utilized to power an external circuit. Over 1 h, our system produced 8.61 L of hydrogen gas at an estimated cost of $8.58 per kilogram of hydrogen gas over the 25-year lifetime of the solar panel.

Proceedings of the 2023 CHI Conference on Human Factors in Computing Systems

Figure 1: Lotion Interfaces sense and react to applied lotion. Left: "Ocean Waves" ring prototype... more Figure 1: Lotion Interfaces sense and react to applied lotion. Left: "Ocean Waves" ring prototype behaves as a fashionable form of personal expression. Right: "Skyscraper Skyline" prototype extends the display capabilities of a smartwatch onto the skin.

The stiff SiNx gate dielectric in conventional amorphous silicon thin film transistors (TFTs) lim... more The stiff SiNx gate dielectric in conventional amorphous silicon thin film transistors (TFTs) limits their flexibility by brittle fracture. We report the effect on the overall flexibility of TFTs of replacing the brittle SiNx gate dielectric with a new, resilient SiO2-silicone hybrid material, which is deposited by plasma enhanced chemical vapor deposition. Individual TFTs on a 50µm-thick polyimide foil were bent to known radii, and measurement of transfer characteristics were made both during strain and after re-flattening. Compared with conventional TFTs made with SiNx, TFTs made with the new hybrid material demonstrated similar flexibility when strained in compression and significantly increased flexibility when strained in tension. Under bending to compressive strain, all TFTs tested delaminated from the substrate for compressive strains greater than 2%. Conventional a-Si:H/SiNx TFTs have been previously found to delaminate at a similar compressive strain. Under bending to tensi...

Extended Abstracts of the 2021 CHI Conference on Human Factors in Computing Systems

Passively consuming digital social media content often precludes users from mindfully considering... more Passively consuming digital social media content often precludes users from mindfully considering the value they derive from such experiences as they engage in them. We present a system for using Twitter that requires users to continuously turn a hand crank to power their social media screen. We evaluate the device and its effects on how users value Twitter with 3 participants over 3 weeks, with the middle week of Twitter usage directed exclusively through our system. Using our device caused a dramatic decrease in Twitter usage for all participants, which either persisted or rebounded in the post-intervention week. Our analysis of diary studies and qualitative interviews surfaced three themes indicating shifting focus on content, shifting awareness about the role of social media, and new social dynamics around content-sharing.

Proceedings of the 2021 CHI Conference on Human Factors in Computing Systems

Figure 1: Exemplar unmaking designs achieved using multi-material 3D printing, exhibiting splitti... more Figure 1: Exemplar unmaking designs achieved using multi-material 3D printing, exhibiting splitting (top left), breaking (top right), and bulging (bottom)

Large Area Circuits for a Hybrid Macroelectronics-Nanoelectronics Active Monitoring System

Deposition of Semiconductor Nanocrystals for Light Emitting Devices

Ultraflexible amorphous silicon transistors made with a resilient insulator

Applied Physics Letters, Jan 25, 2010

Near-Infrared Light Emitting Device Using Semiconductor Nanocrystals

High-resolution sensing sheet for structural-health monitoring via scalable interfacing of flexible electronics with high-performance ICs

2012 Symposium on VLSI Circuits (VLSIC), 2012

Measurements of the localized state electronic structure of organic solar cells

ABSTRACT Experimental measurements of the band tail density of states distribution in bulk hetero... more ABSTRACT Experimental measurements of the band tail density of states distribution in bulk heterojunction solar cells, are described, with measurements made on P3HT:PCBM and PCDTBT:PCBM. The transient photoconductivity experiment measures the electron and hole drift mobility in the solar cells. The dispersive nature of the electronic transport is directly related to the band tail density of states distribution. The technique is extended to measure the band tail DOS over a range of energies. In each type of cell we observe an approximately exponential band tail, but also find an additional broad distribution of deep states. Measurements of the photocurrent spectral response to low energy provide an alternative measure of the optical absorption spectrum for excitations from the polymer HOMO to the PCBM LUMO. These data also reveal an exponential distribution of band tail states with a slope that is the same as the electron transport measurements.

High-Performance Shortwave-Infrared Light-Emitting Devices Using Core-Shell (PbS-CdS) Colloidal Quantum Dots

Advanced Materials, 2015

Core-shell PbS-CdS quantum dots enhance the peak external quantum efficiency of shortwave-infrare... more Core-shell PbS-CdS quantum dots enhance the peak external quantum efficiency of shortwave-infrared light-emitting devices by up to 50-100-fold (compared with core-only PbS devices). This is more than double the efficiency of previous quantum-dot light-emitting devices operating at wavelengths beyond 1 μm, and results from the passivation of the PbS cores by the CdS shells against in situ photoluminescence quenching.

Proceedings of the 2023 CHI Conference on Human Factors in Computing Systems

The goal of our interface is to allow a general audience interested in food to explore how ingred... more The goal of our interface is to allow a general audience interested in food to explore how ingredients in dishes connect and distinguish different cuisines around the world and how they are used with each other. Insights that we expect our audience to be able to learn after interacting with our interface include what popular ingredients in different cuisines are, what cuisines are similar to each other, and how ingredients are used in conjunction with each other in a cross-cultural context.

ECS Meeting Abstracts, 2010

International Journal of Physical Medicine & Rehabilitation, 2016

Advancements in robotic technologies have enabled a significant improvement in the clinical effic... more Advancements in robotic technologies have enabled a significant improvement in the clinical efficacy of prosthetic limbs for persons with upper and lower-extremity amputations. However, significant challenges still remain in establishing a biomimetic bidirectional neural communication between amputees and their external powered prostheses. Regenerative peripheral nerve interfaces may offer a high-resolution alternative to conventional nerve interface technologies for their unique potential to provide increased biospatial resolution for both the control of and feedback from an external powered prosthesis. Here, we present three separate design for 3-D microchannel arrays, each having 16-20 channels measuring 200 μm by 200 μm: one passive (without integrated electrodes), one active (with integrated electrodes), and one active with a porous collagen scaffold. With the array positioned between proximal and distal nerve sendings, we evaluate their effectiveness in tibial n. regeneration in vivo in both rats (N=4) and ferrets (N=4). Using immunofluorescence, we report robust mixed sensory and motor nerve regeneration through the microchannels in all rats, and weak regeneration in 2 of 4 ferrets, suggesting both interspecies regeneration variability and the lack of benefit of axially oriented collagen in improving ferret nerve regeneration through microchannels.

Chairman, Department Committee on Graduate Students I am indebted to my advisor, Vladimir Bulović... more Chairman, Department Committee on Graduate Students I am indebted to my advisor, Vladimir Bulović, whose support and endless enthusiasm made this work possible and broadened my perspectives as a scientist. I am also grateful for the scientific and moral support from all the members of the Organic and Nanostructured Electronics Laboratory (ONE Lab). I would especially like to thank Yasuhiro Shirasaki and Geoffrey Supran, the group's resident quantum dot light emitting device experts, for patiently sharing their wisdom with me in the past 2 years, and Farnaz Niroui for always being there to help me sort through an endless jumble of ideas about research and life. Additional acknowledgements go to the MIT Henry Ford II Fellowship, the NSF Graduate Research Fellowship, and the DOE Center for Excitonics for generously funding my work. Finally, I am forever thankful for the many other wonderful people who helped me find my way (and survive) to where I am, including but not limited to my undergraduate research advisors, Sigurd Wagner and Naveen Verma, my mother, and everyone else who has ever made me think or laugh.

Physical Review B, 2011

Experimental and theoretical studies of the electronic structure of bulk heterojunction (BHJ) org... more Experimental and theoretical studies of the electronic structure of bulk heterojunction (BHJ) organic solar cells are reported. The photoconductivity spectral response of the solar cells has a weak absorption band extending from the band-gap energy down to <1 eV due to charge-transfer optical excitation at the interface between the polymer and the fullerene. The low-energy absorption indicates an exponential band tail of localized states and an absorption model based on the one-electron joint density of electronic states accounts for the data. Transient photoconductivity measurements of the carrier mobility exhibit a temperature-dependent carrier dispersion. Data analysis for the particular case of transport in the BHJ structure is developed. A multiple trapping model of the dispersive transport is consistent with localized band tail states having a comparable density-of-states distribution to those observed by optical absorption. Theoretical calculations of the density of states including disorder in the π-π spacing of the polymer chains also shows exponential band tailing. A density-of-states model is developed from the data and is discussed.

Organic Electronics, 2011

The series resistance of a bulk heterojunction solar cell diode affects the measurement of the vo... more The series resistance of a bulk heterojunction solar cell diode affects the measurement of the voltage dependence of the diode photocurrent, P(V). An empirical model for the effect is described and shows that P(V) can be significantly modified, particularly at high bias voltages. Experimental measurements on PCDTBT:PCBM solar cells with added series resistance demonstrate the effect and confirm the model. The model provides a method to correct the photoconductivity data using measured quantities.

International Journal of Hydrogen Energy, 2011

As a highly reactive gas, hydrogen presents significant challenges for its acquisition and safe s... more As a highly reactive gas, hydrogen presents significant challenges for its acquisition and safe storage. Consequently, the viability of a sustainable hydrogen economy greatly depends on the development of an efficient, cost-effective method of hydrogen production. One model for addressing this challenge is to deploy portable hydrogen generators for the home. The Princeton University Chapter of the International Association for Hydrogen Energy (IAHE-PU) has designed and created a generator that produces hydrogen through water electrolysis and optimizes cost effectiveness and portability while maximizing hydrogen output. For our proof-of-concept, the system utilizes simple household items with a Sharp ND130UJF 130W solar panel. In our design, Ni electrodes submerged in 8 M KOH solution in six glass containers were utilized to power an external circuit. Over 1 h, our system produced 8.61 L of hydrogen gas at an estimated cost of $8.58 per kilogram of hydrogen gas over the 25-year lifetime of the solar panel.

Proceedings of the 2023 CHI Conference on Human Factors in Computing Systems

Figure 1: Lotion Interfaces sense and react to applied lotion. Left: "Ocean Waves" ring prototype... more Figure 1: Lotion Interfaces sense and react to applied lotion. Left: "Ocean Waves" ring prototype behaves as a fashionable form of personal expression. Right: "Skyscraper Skyline" prototype extends the display capabilities of a smartwatch onto the skin.

The stiff SiNx gate dielectric in conventional amorphous silicon thin film transistors (TFTs) lim... more The stiff SiNx gate dielectric in conventional amorphous silicon thin film transistors (TFTs) limits their flexibility by brittle fracture. We report the effect on the overall flexibility of TFTs of replacing the brittle SiNx gate dielectric with a new, resilient SiO2-silicone hybrid material, which is deposited by plasma enhanced chemical vapor deposition. Individual TFTs on a 50µm-thick polyimide foil were bent to known radii, and measurement of transfer characteristics were made both during strain and after re-flattening. Compared with conventional TFTs made with SiNx, TFTs made with the new hybrid material demonstrated similar flexibility when strained in compression and significantly increased flexibility when strained in tension. Under bending to compressive strain, all TFTs tested delaminated from the substrate for compressive strains greater than 2%. Conventional a-Si:H/SiNx TFTs have been previously found to delaminate at a similar compressive strain. Under bending to tensi...

Extended Abstracts of the 2021 CHI Conference on Human Factors in Computing Systems

Passively consuming digital social media content often precludes users from mindfully considering... more Passively consuming digital social media content often precludes users from mindfully considering the value they derive from such experiences as they engage in them. We present a system for using Twitter that requires users to continuously turn a hand crank to power their social media screen. We evaluate the device and its effects on how users value Twitter with 3 participants over 3 weeks, with the middle week of Twitter usage directed exclusively through our system. Using our device caused a dramatic decrease in Twitter usage for all participants, which either persisted or rebounded in the post-intervention week. Our analysis of diary studies and qualitative interviews surfaced three themes indicating shifting focus on content, shifting awareness about the role of social media, and new social dynamics around content-sharing.

Proceedings of the 2021 CHI Conference on Human Factors in Computing Systems

Figure 1: Exemplar unmaking designs achieved using multi-material 3D printing, exhibiting splitti... more Figure 1: Exemplar unmaking designs achieved using multi-material 3D printing, exhibiting splitting (top left), breaking (top right), and bulging (bottom)

Large Area Circuits for a Hybrid Macroelectronics-Nanoelectronics Active Monitoring System

Deposition of Semiconductor Nanocrystals for Light Emitting Devices

Ultraflexible amorphous silicon transistors made with a resilient insulator

Applied Physics Letters, Jan 25, 2010

Near-Infrared Light Emitting Device Using Semiconductor Nanocrystals

High-resolution sensing sheet for structural-health monitoring via scalable interfacing of flexible electronics with high-performance ICs

2012 Symposium on VLSI Circuits (VLSIC), 2012

Measurements of the localized state electronic structure of organic solar cells

ABSTRACT Experimental measurements of the band tail density of states distribution in bulk hetero... more ABSTRACT Experimental measurements of the band tail density of states distribution in bulk heterojunction solar cells, are described, with measurements made on P3HT:PCBM and PCDTBT:PCBM. The transient photoconductivity experiment measures the electron and hole drift mobility in the solar cells. The dispersive nature of the electronic transport is directly related to the band tail density of states distribution. The technique is extended to measure the band tail DOS over a range of energies. In each type of cell we observe an approximately exponential band tail, but also find an additional broad distribution of deep states. Measurements of the photocurrent spectral response to low energy provide an alternative measure of the optical absorption spectrum for excitations from the polymer HOMO to the PCBM LUMO. These data also reveal an exponential distribution of band tail states with a slope that is the same as the electron transport measurements.

High-Performance Shortwave-Infrared Light-Emitting Devices Using Core-Shell (PbS-CdS) Colloidal Quantum Dots

Advanced Materials, 2015

Core-shell PbS-CdS quantum dots enhance the peak external quantum efficiency of shortwave-infrare... more Core-shell PbS-CdS quantum dots enhance the peak external quantum efficiency of shortwave-infrared light-emitting devices by up to 50-100-fold (compared with core-only PbS devices). This is more than double the efficiency of previous quantum-dot light-emitting devices operating at wavelengths beyond 1 μm, and results from the passivation of the PbS cores by the CdS shells against in situ photoluminescence quenching.