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Homo Viridis presents a hybrid environment, within which the boundaries between humans, technology and plant life have blurred. It examines how we as humans perceive our surroundings and seeks to question whether we are able to sense and cognize what other living organisms might experience.
The installation space consists of a wearable soft robotic skin and a Monstera Deliciosa plant placed on a pedestal. The pneumatic sleeve inflates and attains uncannily organic shapes when the plant is touched. Doing so, it delivers a visceral haptic feedback to the person wearing it, that bystanders can also detect visually. The installation transduces (converts into another form) tactile stimulations of the Monstera Deliciosa plant, so that they come to unfold on a physical scale that fits the human sensorium.
A visitor wearing the soft robotic sleeve is offered an intimate experience of inhabiting, connecting, or synchronizing with the senses of another organism through technology, evoking visions of a future where technologically mediated interspecies communication might be possible.
The title, Homo Viridis, is a play on the systematic name for the extant human species, Homo Sapiens (Latin for ‘wise man’ (Tattersall 1998)). Viridis roughly translates to ‘green’, ‘flourishing’, ‘vigorous’ or ‘lively’.
Background
There is a growing literature on plant movement, in relation to science see for instance Fromm & Lautner 2007 and in relation to interaction design see Kuribayashi & Wakita 2006 and Aspling et al. 2016. Scientists have also investigated how the two types of electrical long-distance signals in plants known as action potentials (AP’s) and variation potentials (VP’s) can be measured and even used as sensor signals in biohybrid technological systems (Brenner, Stahlberg, Mancuso, Vivanco, Baluska, & Van Volkenburgh 2006: 415). Recent studies have debated whether plants have senses and are intelligent, which of course depends on terminology and how one defines ‘senses’ and ‘intelligence’ (Mancuso & Viola 2015: 2,4-5). Although research shows that plants can sense and perform information processing, there is still no general agreement on how plant intelligence should be understood (see Chamovitz 2012).
Technical realization
For Homo Viridis, we would ideally have liked to tap into the actual sensing signals of a plant, such as the electrical variation potential or the action potential. The variation potential is a hydraulically propagating electrical signal occurring exclusively in plant cells. And the action potential is a rapid rise and fall in the cell membrane potential in a specific cell location in a plant. Measuring these naturally occurring signals in plants requires sophisticated and well-calibrated equipment and necessitates the insertion of electrodes inside the plant. Realizing a reliable technical system capable of this was beyond the scope of the project. For the installation, we therefor chose to instead use the plant as what one might term a capacitive interface that detects touch and closeness of humans. It was our hope that an experience of synchrony and an associative link between the plant’s and the human interactant’s sensations would still emerge.
In physics, capacitance is defined as the ratio of the change in electric charge of a system to the corresponding change in its electric potential. It is a measure of how much charge a system is able to hold onto at a specific electric potential (voltage). The microcontroller in the installation can measure the capacitance of the plant, by measuring the time it takes for it to reach a specific fraction of an applied voltage. The capacitance of a plant changes when a human body comes within close distance of it (due to a change in the electrical field) and this change is even more drastic when the plant is touched by a human (as the capacitance measured is now the capacitance of the human and plant together). The microcontroller is therefore able to infer if the plant is close to a human or if it is being touched by a human based on the capacitance value it measures.
The capacitive sensing system is based on code and hardware suggested for Paul Badger’s (n.d.) Capacitive Sensing Arduino Library. A wire was connected to a plant stem and capacitance values read with the Arduino microcontroller. Empirical tests were performed to find out how the input value from the capacitive sensor corresponds with human proximity and touch, and these tabulated values were incorporated into the final code. The microcontroller was then programmed to initiate and alter the soft robotic sleeve’s sequence of movements accordingly.
