I was trained as a "traditional" industrial designer. That is to say my formal education in this field revolved around the design and manufacturing of mass-produced goods like lifestyle products and consumer electronics. For the most part of my undergraduate studies, I was certain I would end up as a furniture designer. In my final year, I was exposed to generative design and computational design through platforms like Grasshopper and Processing. Designing a physical structure by defining the rules and constraints that govern its form (rather than specifying every detail manually) was a very appealing process for me. I was attracted to the complexity that emerged from a simple set of rules—complexity that was inconceivable with a manual design process. As I explored programming as a design process, my attention shifted from creating physical form, to supporting physical experiences that unfold across physical and digital worlds. This led me to the field of HCI.

My research today combines my practice in industrial design and computational design with the area of tangible computing within HCI. I am particularly drawn to everyday material culture, and I see the potential in leveraging objects that are already present—for tangible computing [1]. However, rather than treating everyday objects as a platform to add physical computing on top of, I have been investigating these objects as a physical computing material.

How can familiar, ready-made, everyday objects become a new physical computing material?

Objects around have been built for a particular purpose: paper for writing, bowls to store food in, and chairs to sit on. We have developed and formalized design practices and communities around the making of these things, for instance, book binding, ceramic craft, furniture design. Objects are thus produced and set on predetermined trajectories of use in our world. Through my research, I have come to realize that with a slight twist in the way we use them, and by examining the underlying composition and structures that form these things, everyday objects point to new potential as materials [2].

To offer some examples of how I pursue this research agenda, I want to reflect on two research projects that demonstrate uncovering new trajectories of existing objects as a material for physical computing. For these projects, my collaborators and I were interested in investigating new materials that designers can use for physical computing (embedding electronics into physical objects to achieve computing capabilities) and tangible interaction design. Our broad goal was to expand the materiality of ubiquitous computing systems through familiar objects—and probe how such everyday objects might participate in "weaving computing systems into everyday life" [3]. In the first project, we explored carbon-coated paper, a material that is currently used as a worksheet for the science classroom. In the second project, we explored glazed ceramic, a common material used for dining ware and architectural tiles.

Rather than a report on research findings, I will adopt a more anecdotal approach, and share the process my collaborators and I took in these explorations.

  Exploring Carbon-Coated Paper

"Sensing Kirigami." Clement Zheng, Hyunjoo Oh, Laura Devendorf, and Ellen Yi-Luen Do. DIS 2019 [4].

Carbon-coated paper is a sheet material that is mainly used in the physics classroom for modeling the properties of electricity. It is essentially composed of carbon fibers mixed with paper fibers. As a resistive (poorly conductive) material, educators use carbon-coated paper to physically demonstrate the relationship between electric potential, current, and resistance. A typical science classroom experiment using carbon-coated paper involves connecting two edges of the sheet to a DC power source, measuring the voltage at different points on the sheet, and drawing contour lines that connect points with the same voltage.

We stumbled on carbon-coated paper while searching for electrically conductive sheet material that behaves similarly to paper. While playing with this material and characterizing its properties, we observed that its resistive properties changed when it was cut, folded, or bent. We were curious to see if this material can be shaped to give a predictable resistive response, and therefore be able to be used as a physical computing component for tangible interaction design.

With that in mind, we took the material and made a range of paper swatches; simultaneously exploring the 3D forms that we can make with this material, as well as measuring their electrical behavior when deformed. However, this open-ended exploration did not clarify the electrical behavior of this material. Some samples had an increase in electrical resistance when deformed while others exhibited the opposite, and some samples had inconsistent behavior or no change at all (see Figure 1).

We took reference from related work in interactive inkjet-printed circuits (Flexy [5], in particular) and developed a more systematic set of tests to characterize carbon-coated paper. One series of tests measured the material's electrical resistance when bent to form curves of different radii, while another series of tests measured the same property when the material was folded with a sharp crease and held at different angles. There were two brands of carbon-coated paper in the market at that time, PASCO and Science First. We conducted this experiment on both brands, measuring three samples of each type of material for every test.

This experiment revealed that while they were marketed as the same material for the physics classroom, the two brands of carbon-coated paper had completely different electrical behaviors when deformed. PASCO paper's electrical resistance changed predictably when bent but performed erratically when folded. Conversely, Science First paper's electrical resistance decreased when folded, but showed no significant response to bending. With the experiment results, we took another close look at the material; this time, examining the material's structure under a macro camera lens. This revealed the very different structures between PASCO and Science First paper. PASCO paper comprises a thin carbon coating on top of a kraft paper backing, while Science First paper was thicker and had carbon fibers distributed throughout the thickness of the sheet. These different structures led to their individual resistive behaviors. For instance, the carbon layer on PASCO paper cracks along the crease when folded, resulting in an unstable electrical connection across the fold (see Figure 2).

From the experiment results and a clearer understanding of the structure of different brands of carbon-coated paper, we were able to develop a simple heuristic for building tangible user interfaces with this material. Carbon-coated paper can function as a resistive sensor upon applying physical deformations: bending-based interactions can be sensed with PASCO paper, while folding-based interactions can be sensed with Science First paper. The experiment also explained the resistive behavior exhibited by the first series of swatches. Essentially, for a complicated paper structure with multiple folding or bending modules, the change in electrical resistance is the sum of the behavior across all modules.

With this heuristic as a building block, we developed a range of applications to showcase how designers might use this material for tangible computing. Carbon-coated paper can be easily laser engraved and cut. We leveraged this process to simultaneously define sensing circuits that run through the material, as well as cut physical structures that deform predictably during interaction. We engraved sensing circuits on these patterns by tracing a route through multiple folds and bends to compound their change in resistance during interaction. The first application we developed was a series of sensor patches to measure folding and bending. In this application, we wanted to showcase fabricating a full voltage divider circuit on the material itself to support resistive sensing. This includes engraving meandering traces on the material that functions as a constant resistor that is optimized to the sensor range of deformation (see Figure 3a). The next two applications we built took reference from traditional kirigami patterns and transformed these patterns into a set of tangible inputs (see Figure 3b), as well as a sensing lamp shade (see Figure 3c). In these applications, we wanted to demonstrate how such paper with familiar cut and folded patterns can form a deformable structure with clear affordances for physical interaction and serve as a physical computing structure that facilitates resistive sensing.

In this exploration, we took carbon-coated paper out of the science classroom and examined its material composition through the lens of interaction design. By deconstructing its material properties, we found we could shape this material through laser cutting and paper craft techniques into three dimensional forms that behaved as resistive sensors that measure folding and bending. Our findings open up new trajectories for carbon-coated paper as a physical computing material that can be remade into tangible user interfaces.

  Exploring Glazed Ceramic Ware

"Crafting Interactive Circuits on Glazed Ceramic Ware." Clement Zheng, Bo Han, Xin Liu, Laura Devendorf, Hans Tan, and Ching-Chiuan Yen. CHI 2023 [6].

Glazed ceramic is a versatile everyday material. For a long time, humans have harnessed its many qualities to create both practical and decorative objects at various scales. This includes everything from dining and kitchenware to home and architectural fixtures.

This material exploration was inspired by the "Spotted Nyonya" series of porcelain pieces by Hans Tan, a Singaporean designer and ceramic artist [7]. In this series, Hans transforms Nyonya porcelain ware which were traditionally used by Chinese-Peranakan people in Southeast Asia, into objects with a contemporary spotted pattern. Hans developed the resist-blasting process to create these pieces. Resist-blasting is conceptually similar to the resist-dyeing process for selectively adding dyes to fabrics. First, a pattern is cut on vinyl stickers and transferred to the surface of the glazed ceramic object. Second, the object is sandblasted—a subtractive process where the object is exposed to a high-pressure stream of abrasive particles. The vinyl stickers on the object's surface serve as a mask that resists abrasion; sandblasting therefore only removes material at exposed areas. Finally, the stickers are removed, and the transformed object is cleaned.

As his colleagues, we had the opportunity to observe Hans' resist-blasted pieces up close. Besides the visual transformation of the glazed ceramic object, we also noticed the different physical textures that resist-blasting creates on the surface. Ceramic glaze is a vitreous (glass-like) material that is hard, glossy, and smooth. Bare ceramic in contrast, is a rough and slightly porous material. Resist-blasting defines rough valleys of bare ceramic that are surrounded by glazed plateaus on the object's surface. We saw an opportunity to leverage these contrasting textures for circuit fabrication. We hypothesized that conductive ink would adhere to the rough and recessed ceramic body but not the smooth glazed surface. In that case, traces can be engraved into the surface of glazed ceramic objects via resist-blasting and filled with conductive ink to form functional electronic circuits.

With the goal of crafting circuits on glazed ceramic ware, we began investigating how resist-blasting might be adapted to instrument such objects with conductive traces. Despite our proximity to Hans and the resist-blasting technique, there were still many gaps between his practice and our goal of crafting circuits. For instance, electronic traces are typically long meandering lines that branch across a circuit board to transmit signals and connect components together. Such structures are different from the patterns that Hans employs in his work—small repeating motifs that cover the surface of the ceramic object. We took inspiration from pattern making in garment design and explored creating long unbroken traces on vinyl stickers and transferring them accurately onto the three-dimensional surface of ceramic vessels. We also explored various means of removing excess conductive ink from the glazed surface, eventually discovering scraping as a viable process for this purpose—and that it was also a common process used in ceramics craft.

At the end of this exploration, we arrived at an approach to incorporate conductive circuits into glazed ceramic objects. This process begins with resist-blasting circuit patterns onto the object, followed by painting conductive ink onto the circuit regions. Excess conductive ink is then scraped off the glazed surface to reveal the clean and recessed conductive traces defined by resist-blasting. We crafted a series of ceramic swatches that physically demonstrate this approach and its characteristics for others to learn from. This includes a resist-blasting swatch that visualizes the dimensional constraints of the process and a set of tiles that demonstrate five types of interactive circuits that designers might build with this approach. Based on the approach we developed, we also built different prototypes for interactive home applications. These prototypes probed how everyday ceramic objects might participate in activities around the house. For example, kitchen tiles that can sense temperature or moisture, or dining vessels that can control home appliances, monitor eating behavior, and even keep food hot.

Glazed ceramic objects are everywhere. In the research, we deconstructed the layered structure of this ubiquitous material and investigated how it might be used as a substrate for electronic circuits. This investigation revealed not only new uses of everyday ceramic ware as a medium for interactive home interfaces, it also demonstrated how traditional ceramic craft processes can participate in the construction of computational artifacts.

  Unmaking and Remaking Everyday Objects

As I look back on my journey into HCI research, it is apparent how I am influenced by my roots as an industrial designer. I am attracted and keenly aware of the physical "stuff" around us. I have come to appreciate these everyday things as a resource for interaction design and tangible computing.

If I were to distill my current research practice into keywords, I would characterize it as a process of unmaking and remaking everyday objects. In my research practice, unmaking points to deconstructing ready-made products and defamiliarizing oneself to their intended functions and composition. Alongside perspectives around "unmaking" in prior HCI literature, which is about designing intentional breakdown of made objects through manual intervention or natural decomposition [8, 9], I view "unmaking" as a critical part of my design process where objects are deconstructed to uncover hidden qualities and structures that they offer for interaction design. These new insights can then be directed toward using the object as a material that can then be remade with other materials into new tangible computing systems.

In the two projects discussed, carbon-coated paper and glazed ceramic objects were first isolated from their contexts of use and deconstructed into their fundamental material structures. This revealed structural details within these materials that had the potential for interaction design. Different brands of carbon-coated paper showed different resistive behaviors during physical deformation, while the properties of the different layers that make up a glazed ceramic object presented opportunities as a circuit substrate. My collaborators and I then took these insights and used the objects as a material to be remade into new interactive systems. Interestingly, remaking first involved subtracting material from both carbon-coated paper and glazed ceramics, before adding any additional computing infrastructure. Selectively removing material from these objects enabled us to define traces for circuits that sense physical interactions.

Like most design processes, unmaking and remaking everyday objects into interactive systems is a messy and tacit process. Articulating this process as HCI research is challenging, and I have developed a few strategies over time that I use when communicating my work to the broader research community.

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By examining the underlying composition and structures that form these things, everyday objects point to new potential as materials.

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From my experience, I have found it important to not only discuss my exploration findings, but also lay out the exploration process such that others can replicate or extend the approach. In the case of carbon-coated paper, we detailed in our publication the jigs and tools that we used to characterize the resistive behavior of the two brands of material, as well as the electrical fasteners that we used to connect the paper circuits to the broader physical computing system. During the review process, a reviewer commented: "by documenting the complete pipeline for testing and using these materials, this work guarantees that even if these two types of materials were unavailable to a particular designer, this designer could still follow these testing strategies to find alternatives." It was encouraging to see another researcher identify these details as important; and the comment was also prophetic as the Science First brand of carbon-coated paper was discontinued one year after we published the pictorial.

Swatches were also helpful in communicating a tacit material exploration process. In our publication for the work on glazed ceramic ware, we documented our exploration into resist-blasting in the form of a dining plate with a series of sandblasted traces. These traces captured the effect of sandblasting on different design parameters, such as the width of the trace or the gap between traces. We took high resolution photographs of this plate and packaged it as a swatch document that we included in the paper. Through this swatch, we hope to communicate not only quantitative findings (such as the minimum trace width), but also qualitatively present the effects of resist-blasting for others to see.

In this article, I recounted my journey from design into HCI, and discussed the overarching research agenda that guides my work. I also recounted two material explorations and the processes that my collaborators and I took for investigating these materials for HCI. I reflected on these projects and discussed my practice as one that is characterized by unmaking and remaking everyday objects for tangible computing. I hope sharing this offers a glimpse into the details of a personal research approach that is often implicit in academic publications. I also hope this inspires and provokes others to consider how we look and engage with the familiar things around us.

  References

[1] Hallnäs, L. and Redström, J. From use to presence: on the expressions and aesthetics of everyday computational things. ACM Transactions on Computer-Human Interaction [TOCHI] 9, 2 [2002], 106–124.

[2] Barati, B. and Karana, E. Affordances as materials potential: What design can do for materials development. International Journal of Design 13, 3 [2019], 105–123.

[3] Weiser, M. The computer for the 21st century. Scientific American 265, 3 [1991], 94–105.

[4] Zheng, C., Oh, H., Devendorf, L., and Do, E. Y. L. Sensing kirigami. In Proceedings of the 2019 on Designing interactive Systems Conference [DIS '19]. ACM, New York, 2019, 921–934.

[5] Vadgama, N. and Steimle, J. Flexy: Shape-customizable, single-layer, inkjet printable patterns for 1d and 2d flex sensing. In Proceedings of the Eleventh International Conference on Tangible, Embedded, and Embodied Interaction [TEI '17]. ACM, New York, 2017, 153–162.

[6] Zheng, C., Han, B., Liu, X., Devendorf, L., Tan, H., and Yen, C. crafting interactive circuits on glazed ceramic ware. In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems [CHI '23]. ACM, New York, 2023.

[7] Tan, H. Spotted Nyonya. 2011; https://hanstan.net/works/detail/spotted-nyonya

[8] Song, K. W. and Paulos, E. Unmaking: Enabling and celebrating the creative material of failure, destruction, decay, and deformation. In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems [CHI '23]. ACM, New York, 2023, 1–12.

[9] Song, K. W., Maheshwari, A., Gallo, E. M., Danielescu, A., and Paulos, E. Towards decomposable interactive systems: Design of a backyard-degradable wireless heating interface. In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems [CHI '22]. ACM, New York, 2022, 1–12.

  Author

Clement Zheng is a design technologist and HCI researcher. He is particularly interested in exploring alternative material approaches for designing interactive systems. He is currently teaching and researching in the Division of Industrial Design at the National University of Singapore.

  Figures

Figure 1. A snapshot of the interactive swatches explored with carbon-coated paper.

Figure 2. (a) Material composition of PASCO paper. (b) Cracks in the carbon layer along the crease when PASCO paper is folded. (c) Material composition of Science First paper. (d) Bunching up of carbon fibers along the crease when Science First paper is folded.

Figure 3. Interactive applications made with carbon-coated paper: (a) bend sensing patch, (b) tangible inputs, and (c) sensing lamp shade.

Figure 4. (a) Resist-blasting a masked ceramic bowl inside the sandblasting machine. (b) Cross section of a sandblasted region on a glazed stoneware object.

Figure 5. Collection of ceramic objects with embedded interactive circuits crafted via the resist-blasting approach.

 

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