Adobe Research Scientist, Christine Dierk, unveiled an intriguing new project called Project Primrose at the Adobe Max conference. Project Primrose showcases a dress adorned with a series of liquid crystal panels that can react to movement, thereby altering the design of the dress. Recently, Adobe released a paper highlighting some of the technical aspects of the dress.
The paper, presented at the User Interface & Software (UIST) conference in 2022, discusses the utilization of the same technology in a canvas and a handbag. The dress employs Polymer-dispersed Liquid Crystal (PDLC) panels from Shanghai HO HO Industry Co, typically used for windows and doors to ensure privacy. The dress employs an Iradium Tin oxide-coated PET film that is initially opaque but becomes transparent when a voltage difference is applied.
The PDLC panels are meticulously shaped in a hexagonal pattern and interconnected with flexible printed circuit boards (PCBs) through a daisy chain. Interestingly, Christine Dierk discovered that reducing the size of the panels resulted in lower voltage requirements for activation. For the canvas example, the voltage was substantially decreased to safer levels, ranging from -15V to 15V, making it much safer for a wearable device.
When triggered, the panels exhibit a “soft ivory” appearance when layered over a reflective material. The paper also explains that greyscales can be achieved through Pulse Coded Modulation (PCM), enabling the variation in panel transparency. By driving the panels at a frequency of 3.2KHz, a total of 64 shades of grey were achieved.
The dress’s primary controller consists of a customized PCB featuring a Teensy 4.1 microcontroller and a BlueFruit LE SPI module. Power is supplied by two 14.8V Lithium Polymer (LiPo) batteries, with converters enabling the provision of power to the chips and switch modules. The Teensy microcontroller directly controls the -15V and +15V levels required to trigger the panels by switching between the two batteries.
The dress’s array is constructed from multiple modules, with each module comprising four panels connected to a controller PCB. Analog Signal Device (ASD) ADG1414 chips within the controller PCB receive signals from the bus and use switch registers to control each individual panel.
The implementation of bus modulation allows for both power delivery and bus signal transmission within the daisy-chained modules. This is achieved through -15V and +15V levels modulated with a 50Hz square wave to power the panels and transmit the bus signal simultaneously.
The Teensy 4.1 microcontroller serves as the central control unit for the entire system and leverages its Inertial Measurement Unit (IMU) to detect movement and change the dress’s pattern accordingly. Although the dress video does not showcase the electronics, it is estimated that the canvas example consumed a mere 0.58 watts of power, suggesting that the dress likely uses only a few watts.
Undeniably, Project Primrose is an extraordinary creation, exhibiting immense potential. It leaves us pondering the question, “What would you do with this?” The possibilities appear endless.