Unfinished Arch
Rafael Lozano-Hemmer
Antimodular Research
2026
Unfinished Arch is an outdoor, public sculpture installation by Rafael Lozano-Hemmer comissioned by the city of Toronto. The participatory artwork will be a 9-meter-tall incomplete arch that will extend over a prominent waterfront park with one end of the arch left suspended in the air. Visitors will be enticed to complete the arch at its floating edge which contains interactive pressure plates. When the arch is completed by a user touching these plates it will illuminate until they remove their hands.
As the lead designer of the electronic control system and software that drive the artwork I have been responsible for creating the systems that enable its interactivity. Overall, the interaction between viewers and the work is simple; when the load cell sensors - typically used in digital scales - inside the metal plates at the end of the arch register the pressure of a user's touch, the arch begins to illuminate. When the pressure is released the illumination recedes. Creating a permanent, weatherproof, interactive sculpture however, involves a set of challenges that the public should never be prompted to consider.
Pictured from left to right are the custom software application which controls the arch, a printed circuit board containing the analog to digital converters that monitor the pressure plates, and the circuit board being tested with a full load cells.
Reliability has been a major focus of mine during the design of this work. Designing logical redundancies in the custom electronics, protection mechanism for natural phenomenon like lightning, as well as remote debug and control mechanisms ensures that the sculpture will continue to function smoothly.
Perhaps the best part though, is that I have been testing the electronics housed inside a small, sample portion of the arch on the roof of my office to simulate real conditions. This means that every day I go to work I have a great excuse to go outside.
