Biodigital Micro-Cellular Mashrabiya: Lattice Architectural Microbial Membranes for Sustainable Built Environments

Abstract

A typical Mashrabiya in Islamic architecture represents an integral climatic and sustainable solution, not only by offering recycling and the responsible use of small pieces of wood assembled in stunning geometrical and natural abstract lattice panels, but also because it offers air cooling, filtration, and flow from the exterior to the interior of a building. This leads to the air flow being cooled by the water spray offered by the interior patio fountains, in addition to protecting the sanctity and privacy of a building’s inhabitants, which complies with religious beliefs and social considerations. This integral sustainable solution acts on multiple scales: material recycling and responsible use, as well as climatic and socio-cultural considerations similar to Gaudi’s approach with Trencadís technology, not far from the Arabic and Islamic architectural influence revived in the Catalan Modernism contemporary to his time. In these footsteps, we explore the Mashrabiya of our time: an interactive and living architectural membrane, a soft interface that reacts by growing, giving shade, filtrating air, and transforming in time. Despite attempts to design a contemporary concept of the Mashrabiya, none of them have adopted the living organism to form an interactive living lattice architectural system. In this work, we propose the biodigital micro-cellular Mashrabiya as a novel idea and a proof of concept based on employing the authors’ previously published research findings to utilize eco-friendly biopolymers inoculated with useful native–domestic microbial strains to act as soft and living membranes, where these organisms grow and vary in their chemical and physical characteristics, sustainable function, and industrial value. This study implements an analytical–descriptive methodology to analyze the key characteristics of a traditional Mashrabiya as an integral sustainable solution and how the proposed micro-cellular biodigital Mashrabiya system can fulfill these criteria to be integrated into the built environment, forging future research trajectories on the bio-/micro-environmental compatibility of this biomaterial-based biodigital Mashrabiya system by understanding these materials’ physical, chemical, and physiological traits and their sustainable value. In this work, a biodigital Mashrabiya is proposed based on employing previous research findings on experimentally analyzed biomaterials from a biomineralized calcium-phosphate-based hydrogel and bio-welded seashell–mycelium biocomposite in forging the lattice system of a biodigital Mashrabiya, analyzing the feasibility and sustainability impact of these systems for integration into the architectural built environment.

1. Introduction and Background: Revaluation of Mashrabiya as a Soft Membrane and Interactive Environmental Interface

Walking through the ancient streets of Islamic Cairo, Al-Muizz li-Din Allah al-Fatimi Street—an open museum full of architectural phenotypic variations of the genetic code of Islamic architecture, expressed in its varied characteristics, especially in the Fatimid and Mamluk dynasties [1]—one may observe lattice wooden windows that are a breathing membrane to a building and a pleasant visual screen in an urban context [2]. These screens emerged from the Islamic doctrine of preserving the sanctity of a house’s inhabitants by visually blocking the outsider from seeing the insider, while allowing for the insider to securely view outsiders and to view the urban context, creating the need for a see-through material that allows for air flow, light intake, and passive cooling of the building [3], as well as a lightweight structure to fill the wide spans of these architectural openings with cheap and easily operable material. Back then, this was a challenge due to limited construction material options, where buildings were only constructed with adobe, limestone, and wood. The solution emerged from the Islamic philosophy of collaborative systems as expressed in the Hadith, “A faithful believer to a faithful believer is like the bricks of a wall, enforcing each other”, symbolized by clasped hands with interlaced fingers, as visualized by the Prophet Muhammed (peace be upon him) while saying this [4]. This detailed image of a woven, interlaced system of buildings is the typical building principal behind the Mashrabiya, built from little pieces of available wood (small in dimension), and connected to each other in a perfect interlocking system, allowing for air to flow within the interstitial spaces, and allowing for light to flow from the outside to the inside, with a lightweight, contraction-adaptable system and with an infinite possibility for spatial expansion on wide spans of architectural openings.

Moreover, this beautiful architectural membrane not only achieves passive cooling, filtered ventilation, and sparkling light–shade duality, complimented with religious and social considerations, but also their adjacent stone-built platforms (as pronounced in Arabic: “Makaad”) can be used to place drinking water containers (as pronounced in Arabic: “Quolla”) made of fired clay to be cooled by the cool air flow that enters through the openings of the lattice window. From here emerges the name “Mashrabiya”, which means a place of drinking in Arabic. Its other name was “Mashrafiya”, which refers to the same type of system integrated in the upper floors and customized for the “Haremlik”—which is the cluster specialized for women in the house—allowing for them to look from these lattice system openings on the festivals, celebrations, or invited guests in the house without being exposed to strangers or foreign men, complying with the Islamic rules of preserving sanctity. Thus, these Mashrafiyas were usually implemented overlooking celebration or festival halls in a building.

By the end of the 19th century, this sustainable Mashrabiya system fell into decline due to the effect of novel post-industrial revolution materials and the consequent construction systems, where windows started to employ sheet glass, replacing the traditional skilled crafters of the typical Mashrabiya.

However, Mashrabiyas along with other vernacular architecture systems (e.g., earthen architecture) are being revived by the passive-house [5] and ecosystem architecture trends [6], motivated by the search for integral sustainable solutions that minimize a building’s carbon footprint and energy consumption, and realized by adopting passive cooling and enhancing air quality and circulation in a building through the use of functional materials and optimized construction systems.

In the search for a new way of designing the filling of an architectural opening, the emergence of new technologies in the metal and sheet-glass industry has gradually erased the pores on these architectural membranes to become radical holistic systems—either open or closed, light or dark. This radicality in a window′s phase shifting harms the building′s climatic control. The exaggerated closure of the building fully separates it from its surroundings, blocking the air, sound, and sometimes light by closing these glass–aluminum windows, or the contrary by excessively allowing all of these environmental parameters all at once without moderation, by opening. These wide curtain glass sheet windows imported by the rational functionalism of internationalization do not accept adoption or adaptation to various climatic zones. For example, these systems are not compatible with desert and dry climates, in addition to their neglect of the cultural identity of these locations, giving no merit to adopting them at the cost of abandoning native sustainable integral solutions such as the Mashrabiya.

Searching for novelty is the human inherent need to explore the potential of new materials, technologies, and design tools that are products of our time. Since the technology of construction controls the freedom of design to a wide extent, some attempts to reintroduce the concept of the Arabic Mashrabiya in some of its functions have been explored in the literature. For example, the façades of the Institut du Monde Arabe (1987) focused on the light moderation achieved by the Mashrabiya-inspired system. However, this was not a self-sufficient sustainable solution performed by the material level itself, but rather a function of employing complex mechanical parts to achieve a camera-like kinetic movement regulated by sensors and motors to unify the interior intake of day-light, while representing the outer envelope with varied openings! This resulted in a façade with an exterior appearance of standardized machine parts while the interior suffered from a dim and blue-grey light effect.

Another example of the same concept of employing machine kinetic parts and sensors to moderate the light intake of a building is the Abraj Al Bahr Towers in Abu-Dabi (2012) [7], although they achieved more control of the interior light intake and consequently also the interior heat gain; however, as with the Institute du Monde Arabe [8] and the Doha Tower (2012) [9], the exaggeration in the Mashrabiya-inspired pattern scale in all the three projects fails to correspond to the original Mashrabiya fractality. This is not to mention that the materials employed in these designs were mainly various metal alloys and sheet glass curtain walls which are anything but compatible with the desert climate or its environmental conditions. Thus, these attempts could not successfully address the multi-scale sustainability of a typical Mashrabiya as a passive system achieved with the least materials and processes. It is even fair to say that these attempts contradicted the concept of the typical Mashrabiya by using mechanical electronic and non-autonomously operating systems that create an additional need for electricity and maintenance. Based on these criteria of balancing the input with the output, employing the location´s available and compatible resources, and not racing after importing high-tech innovations in materials and systems, several articles in the literature in the last decade [10] do not qualify to be compared with the typical Mashrabiya. This is due to their dependence on sensors and mechanistic parts with complex electric circuits and pathways to automate these systems, making them less passive and less sustainable and meaning they fail to compare to the durability of the original Mashrabiyas that resisted the harsh desert climatic conditions and geological disruptions (e.g., seismic activity) where they were implemented for more than 500 years.

Another bio-inspired example is Fibonacci’s Mashrabiya (2009) [11], focused on the variation in light intake by a monolithic, bio-inspired, Voronoi cell system following a spiral attractor, decreasing and increasing the size of their openings in an interesting duality, using a translucent material varying in its density by controlled material deposition 3D printing to create an interesting visual effect. This example addresses only the light moderation aspect of the typical Mashrabiya while failing to address the Mashrabiya concept and philosophy as discussed in the first section of this work, which is based on integral sustainability spanning many aspects. These include light regulation between the interior and exterior, the air flow and filtration achieved by the wooden small interlocking pieces with their microstructures, and the infinite possibility of harmonical extension of the system based on the same logic—also known as weaving an infinite fabric as a solidarity symbol of the religious belief: expansion, harmony, solidarity, sustainable material use through recycling and customization, unity and variation, the functionality of light and air quality, and socio-cultural congruency. Figure 1 exhibits the Typical Mashrabiya Technology Criteria, identifying the full functions and integral sustainability which define a Mashrabiya system. These criteria are used to evaluate the authors’ own approach in designing the biodigital micro-cellular Mashrabiya in the following sections of this work.

Thus, these seven key characteristics of a Mashrabiya cannot be reduced to only the light moderation criterion, signifying the need to forge the new materials and technologies to propose a 21st-century Mashrabiya: a system that fulfills all seven aspects and adds more. Thus, in the following section, the idea of a biodigital Mashrabiya is proposed by analyzing the feasibility of employing previous biomaterial research findings in synthesizing a 21st-century biodigital Mashrabiya. We propose the use of a bio-welded sea-shell-based biocomposite material welded by mycelium and an artificial bone mineralized hydrogel to be employed in developing the biodigital Mashrabiya. A comparison between these two biomaterials and their potential use in a biodigital Mashrabiya will be presented in the Section 2. Then, the limitations of this research trajectory will be analyzed in the Section 3.

2. Methodology

2.1. The 3D-Printed Biodigital Microbial-Cellular Mashrabiya: The Interactive Living Membrane Feasibility

In the search for a 21st-century Mashrabiya that utilizes advanced functional material research and novel technologies while complying with the 7 key sustainable functions of the traditional Mashrabiya, integral solutions were analyzed to propose added values of fostering biodiversity and forging a lightweight breathable lattice structural system as the novel architectural bioactive membrane. This integral approach originated from 3D-printed biodigital clay bricks [12] with customized bio-inspired geometry realized by the reaction-diffusion algorithm to enhance the mechanical properties in compressive strength and elasticity in comparison to the standard clay brick. This system achieved the moderation of light intake by the lattice curvilinear forms that not only imitate the traditional Mashrabiya in its light–shade duality but also draw beautiful bioinspired curvilinear shadows and offering a curtain to diffuse the view of the interior from the outside, conserving the socio-cultural and religious origins of the Mashrabiya, as well as air filtration and cooling by the effect of the porous characteristics of clay material and its microstructure that captures moisture, cools down air, and filters dust and micropollutants, enhancing interior air quality. This is in addition to the material sustainability of clay as an abundant and easily operable material. Integrating the advanced contemporary technology of 3D printing through controlled material deposition facilitates the reproducibility of the system and its democratic adoption and adaptation. The proposed 3D-printed biodigital clay bricks work autonomously as a passive system; however, they suffer from two limitations, failing one point of the seven key-point criteria of a traditional Mashrabiya which is the lightweight structure, since fired clay is heavier than wood—although the lattice design of the biodigital bricks and their reduced weight in comparison to traditional clay bricks can count as a successful adaptation of clay material for this proposed function. The second limitation is the system assembly, although these 3D-printed biodigital clay bricks have proved their elasticity and competent compressive strength in comparison to standard clay bricks; however, the extension of the collaborative system of the Mashrabiya using these clay units is more difficult than the wooden units in the traditional Mashrabiya. This is not to mention that clay material has reduced durability in comparison to wood due to the low clay elasticity post-firing. These limitations of the material led the research into developing biodigital bricks with a customized material design that combines being lightweight with elasticity and durability while fostering biodiversity as well. This is applied and analyzed in the following section on designing a bio-welded myco-biocomposite Mashrabiya.

2.2. The 3D-Printed, Bio-Welded, Myco-Biocomposite Mashrabiya

Bio-welded 3D-printed biodigital bricks using a seashell-based biocomposite welded by mycelium [13] offer an alternative material that is lighter and more autonomously welded than 3D-printed clay bricks that lack autonomous welding and hardening over time, as well solving clay bricks having a heavier weight than the wood in a traditional wooden Mashrabiya. This system achieves a lattice breathing, light structure and a living structure that becomes harder with time as the mycelium grows and bio-welds the seashell-based biocomposite through a biomineralization chain reaction of calcium carbonate generation (Figure 2).

The system of bio-welded, myco-biocomposite bricks achieved the visual camouflage effect of a typical Mashrabiya and the bio-reinforcement of the material on the material-structure scale level, where the densely myco-colonized locations served as growth radiant points extending their hyphal network in a lattice arrangement and allowing the system’s infinite spatial propagation to weld wide spans, allowing light transfer while the layered growth of these bioagents reinforces their existence by reciprocal weaving dense hyphae networks. In addition to the biomineralization recurrent reaction that precipitates calcium carbonate (CaCO₃) to strengthen the system, by consuming carbon dioxide (CO₂) from the air, the system can alleviate the carbon footprint as well. This goes beyond the literature where mycelium-bound materials were experimentally used as possible structural or insulating materials [15,16,17] and elsewhere. In the literature, mycelium composite materials were applied on dense or bulk building blocks, while the bio-welded biodigital bricks achieved bio-welding in fine resolution working in the curvilinear thickness of the biocomposite 3D-printed profiles, miniating the lattice form of the biodigital brick to keep it visible and non-interrupted by fungal hyphae growth. This proves the particular eligibility of this developed bio-active material from the mycelium-bound seashell composite in achieving the lattice structure system of a traditional Mashrabiya, as well as performing air filtration from CO₂ and becoming more rigid over time, allowing for the expanded structural filling of wide-span architectural openings (windows). Furthermore, the majority of mycelium-bound materials in the literature halted the growth of the bioagent (the mycelium) to apply only its product in architectural and construction applications [18,19].

This is unlike the bio-welded seashell–mycelium composite material at hand, which allows continuous growth of the mycelium as a bounding and continuously reinforcing agent to this lattice structure system, providing self-connectivity systems to solve the assembly and tessellation of the original biodigital bricks in a bio- and eco-friendly autonomous method. This is achieved through a bio-decided interplay between the solid and the void, responding to environmental conditions such as temperature, humidity, nutrients, and oxygenation conditions and fulfilling the 7 key-point criteria of a Mashrabiya including light moderation; air-flow moderation; material sustainability, since it is developed from food waste and mycelium; lightweight structure; and autonomous performance. In addition, the system achieves a bioactive, environmentally sensing and responsive system that is self-healing and bio-welded [13].

This proves the promising applications of material scale level functionality and customization in fulfilling the criteria of the traditional Mashrabiya based on the main concept of integral sustainable solutions.

2.3. The 3D-Bioprinted Bone-Inspired Mashrabiya System

Working on the material scale level as the integral solution to achieve customized multi-functionality in a sustainable breathable lattice system, the project “Bone Tissue Architecture” was developed to produce a self-healing acellular-mineralized material that is biomimetically designed to resemble the cortical–trabecular level of the bone tissue. The 3D-bioprinted material was developed from calcium phosphate dibasic enhanced SA-Gelatine hydrogel in specific concentrations treated with three-stage chemical crosslinking. The developed hydrogel exhibited enhanced printability and rheological properties such as coherency, shape retention post-printing, and pre-crosslinking; mineralization in open air in non-sterile conditions; antimicrobial properties; and enhanced cell encapsulation of the osteosarcoma SaOs-2 cells. This is thanks to its biomimetic microstructure where the exterior interfaces of the 3D-printed hydrogel mineralize in open air by consuming CO₂ to start a two-step mineralization reaction to create calcium carbonate and hydroxyapatite, turning into a solid cortical bone-like shell while maintaining the soft inner body of the hydrogel at a slower mineralization rate allowing the viability of the encapsulated cells. This was proved by the mineralization results of the hydrogel exhibited in the SEM images of the outer interface of the hydrogel samples that are in the first interaction site with the surrounding air. This offers a unique cementitious construction material with chronic solidification and antimicrobial traits with self-healing and carbon dioxide-capturing properties [20].

Such a material, with this particular microstructure and system, aligns with the concept of the typical Mashrabiya system on a fractal level. As exhibited in Figure 3, the meso-to micro-scale demonstrates the application of the developed self-healing mineralized material. Figure 3a exhibits the 3D-bioprinted samples of the hydrogel with varied concentrations of calcium phosphate in a lattice 3D form, featuring a rectangular micro-grid infill pattern [20]. The varied rate of mineralization on the outer interface of the printed hydrogel samples resulted in morphological differentiation in texture, color, shape fidelity, and mechanical properties, as exhibited in the four samples of the 3D-printed hydrogel, with four specimens each, corresponding to the varied calcium phosphate concentrations in the hydrogel composition.

Figure 3b exhibits a 3D-printed large-scale panel (20 × 20 cm²) that is printed in PLA (Polylactic Acid), following the biomimetic design of the cortical–trabecular meso-scale, with a material system morphology inspired by the hierarchical structural motifs of bone tissue. Meanwhile, Figure 3c–e present the material′s micro-scale structure under a Scanning Electron Microscope (SEM), exhibiting the mineralized interface of the hydrogel with densely formed hydroxyapatite platelets.

At all three levels of the experimental phases of this 3D-bioprinted bone-like mineralized material, the lattice structure serves as a load-bearing and filling system, as demonstrated [20]. This structure addresses light and air-flow moderation in a more biochemically regulated manner, while also achieving material sustainability by being developed from two of the most abundant biopolymers in nature (alginate and gelatine) and calcium phosphate, which can be sourced from various food wastes [21,22].

Additionally, the mineralized material offers a lightweight, load-bearing structure, while the entire system functions autonomously in an environmentally responsive manner. The system also achieves reproducibility and ease of repair, as it mineralizes in open air, as a self-healing system.

3. Discussion

3.1. Limitations and Future Research Trajectories

Although these two biomaterials have proven their efficiency as a correct trajectory toward integral sustainability solutions—based on the material scale and corresponding with the typical Mashrabiya’s seven key-point criteria—several considerations still need to be addressed to enable real-scale integration and the realization of these systems in architecture and the urban built environment.

For instance, the life cycle of the material in both cases, particularly in the case of the bioactive myco-biocomposite material, remains a challenge for its safe and permanent application in covering wide architectural openings. This is not only due to health considerations—since, although the incorporated fungal strain in this case is safe and even edible, the bioactive chemical composition of the material could invite infections from other harmful or opportunistic fungi (for example, Aspergillus niger and Aspergillus flavus commonly grow alongside Penicillium chrysogenum [23]), bacterial strains, and insects—but also due to the variation in the mechanical properties of the bioactive composite material, which depends on the growth of the bioactive agent, in this case, mycelium. This results in heterogeneous mechanical properties along the material’s span, leading to potential structural instability. Uneven responses to structural loads—whether from the system’s own weight or additional architectural loads—could ultimately result in the system’s collapse when applied in architectural openings. Additionally, as the living bioagent undergoes phases of growth, reproduction, and possible decay, its impact on the system’s feasibility for long-term application must be carefully considered, especially in terms of species coexistence.

Even if the mycelium strains used are non-pathogenic, fungi, in general, are opportunistic. This means they could potentially infect immunocompromised individuals if implemented in an indoor space in a bioactive manner, raising serious concerns about their long-term feasibility and future applications in the built environment.

Moreover, the possible integration of various non-pathogenic fungal strains is governed by location, as fungal species and strains thrive more in their native environments. This raises another question about the possible customization of the production of these myco-biocomposite Mashrabiya systems in various climatic zones and sites. Furthermore, the indefinite biological growth that results in uneven forms and extensions might not yet be socially accepted by various users [24].

Despite these limitations, bioactive materials, especially mycelium-bound composites, have recently been in active research and application due to their economic and sustainability values [25], thanks to their economic and eco-friendly production materials and processes, as well as the possibility of decentralized and democratic production. Additionally, they possess an all-in-one combination of properties, including thermal and acoustic insulation, self-healing capabilities, lightweight composition, affordability, and recyclability. Although they have not yet been adopted as structural materials, the current proposals in the active literature [26,27] regarding the modification of the mechanical properties of mycelium-bound composites play a significant role in advancing the wider application of these materials in the architectural built environment.

These limitations, however, are eliminated in the case of the developed bone-like material and its possible application in the biodigital Mashrabiya, thanks to its antimicrobial properties and the homogeneous composition of the material, which becomes harder over time, offering adequate mechanical strength [19,20,28].

Thus, with the new possibilities provided by advances in functional bioactive material synthesis and 3D-printing technologies, new considerations are being applied to guarantee the safe and sustainable use of these materials on an architectural scale, which corresponds to the biodigital Mashrabiya proposal approach in the current study. Following the analytical–descriptive methodology, this study analyzes the eligibility of the two projects—the 3D-printed myco-biocomposite Mashrabiya and the 3D-bioprinted bone-inspired Mashrabiya—to serve as a 21st-century biodigital Mashrabiya.

Accordingly, the following matrix (

Table 1. Comparison of the 3D-printed myco-biocomposite Mashrabiya and the 3D-bioprinted bone-inspired Mashrabiya to the key criteria of the traditional Mashrabiya.

Typical Mashrabiya Key-Criteria	3D-Printed Myco-Biocomposite Mashrabiya	3D-Bioprinted Bone-Inspired Mashrabiya
Light-intake moderation	Moderately achieved due to the large openings of the lattice curvilinear biodigital bricks design in comparison to the typical Mashrabiya.	Fully achieved varied scale moderation of light intake since this project proposes micro-, meso-, and macro-scale organization of the trabecular-inspired lattice pores, with the added value of the self-organization fractality of the system based on mineralization on the material scale.
Socio-cultural compliance of the Mashrafiya	Moderately achieved in comparison to the interior camouflage effect of the typical Mashrafiya due to the wider voids in the biodigital brick design.	Fully achieved varied scale diffusion and camouflage of the interior based on the fractal varied scale pores of the material system.
Air filtration and flow moderation	Achieved with the added value of air filtration due to the designed material mineralization reaction that captures carbon dioxide to produce and precipitate calcium carbonate as a side product of the interaction between the mycelium and the seashell-based biocomposite [13].	Achieved with the added value of air filtration thanks to the designed material mineralization that captures carbon dioxide in the mineralization pathway of the hydrogel interface reaction with the surrounding air to produce calcium carbonate and hydroxyapatite [20].
	Air cooling and air-flow moderation requires further experimentation in collaboration with the other architectural elements that facilitate the air flow and circulation inside the building.
Material sustainability	Fully achieved since the myco-biocomposite biodigital bricks are developed from recycled seashells from food waste and edible fungi mycelium (Pleurotus ostreatus) which is identified as a current material in sustainability to exploit waste and cheap microbial cultures in architecture and construction.	Partially achieved. Gelatine and alginate are abundant biopolymers that are affordable and available; however, the 3D bioprinter is less economic democratically. Nevertheless, domestically developed and manufactured bioprinters are a possible solution to overcome the cost of commercially available bioprinters.
Reproducibility and easy maintenance	The biodigital myco-biocomposite bricks are considered reproducible and self-healing. However, patch-to-patch variations caused by uneven bioagent growth on the replicated bricks can be considered a challenge in the reproducibility of this system. Another challenge is the inoculation-to-growth duration that can last two weeks minimum and requires further study on the system life-cycle in reaching the full mineralization of the system by the proposed reaction.	The biomimetic bone-like material system is reproducible and easily maintained thanks to its easy preparation procedures and autonomous mineralization. Thus, this system is more suitable for application as a biodigital Mashrabiya.
Lightweight structure	This system achieves an enhanced lightweight structure in comparison to clay and wood. However, further research is required to evaluate the structural and mechanical property variations of the myco-biocomposite material upon mineralization and dense welding by the bioagent (mycelium).	This system achieves a lightweight structure that is based on the material biomimetic morphology of cortical–trabecular hierarchical structural motifs. This qualifies this material system as a fractal load-bearing lightweight system. Further research is needed to study the morphological variation and fractality of the mineralized material, as well as estimating the mechanical property variation chronologically to the mineralization rate and sites.
Autonomous passive operation	This system is autonomously and passively operating by the effect of the bioagent (mycelium) welding and reinforcing the material while absorbing carbon dioxide in the mineralization reaction, generating a coherent welded system of a mineralized biodigital Mashrabiya.	This system autonomously and passively operates by the effect of the acellular chemical mineralization reaction consuming carbon dioxide in the mineralization of the outer interfaces of the material while providing enhanced mechanical performance and the possibility of encapsulating living cells of useful organisms [20] (for instance, bioluminescent bacteria or algae strains) to add to the sustainability of this biodigital Mashrabiya system by fostering biodiversity.
Sustainability added values	This system offers wide potential in sustainability functions in the production of food by employing edible mushrooms’ mycelium as applied in this case using the King Oyster Mushroom [13], as well as producing industrially valuable enzymes (e.g., Laccase) according to the fungal strain used to weld the seashell biocomposite [29]. Another possible added value is the generation of bioelectricity based on the oxidation–reduction reaction of the fungal strain used in the bio-welding of the biocomposite which consumes the auxiliary media in the system [29,30]. This can lead to a fully self-sufficient biodigital Mashrabiya that is an integral sustainable solution for an architectural bioactive and functional membrane.	Because of the excellent encapsulation properties of this biomimetic hydrogel, this system can host and maintain the viability of various useful microbial strains such as bioluminescent algae that can produce oxygen, proteins, enzymes, and naturally emitted light [31]. This is currently under experimentation and will be published in a future study.

) compares the two mentioned projects—the 3D-printed myco-biocomposite Mashrabiya and the 3D-bioprinted bone-inspired Mashrabiya—to the key criteria of the traditional Mashrabiya, as exhibited in Figure 1. This comparison also highlights the added values and possible limitations of these systems, which require further research to validate their scalability and actual implementation on an architectural scale.

3.2. Between 3D Bioprinting and Casting: Future Application of Bioactive Lattice Membranes

The biodigital bioactive lattice Mashrabiya approach exhibited in the two projects analyzed in this study proves that working at the material scale level is a promising approach to achieving integral sustainability solutions, with the system′s inherent characteristics based on synthesis and emergence rather than mere assembly. Although 3D-printing technology has been advancing rapidly, particularly in the biomedical and biomaterial fields [32,33,34], scaling up these bioprinting technologies to an architectural scale amplifies the material limitations—especially regarding the viability of bioactive agents (e.g., encapsulated cells), stability, and the physiochemical reactions and properties within the material itself and its interaction with the surrounding environment.

Additionally, adjusting the rheological properties of biomaterial pastes, such as biocomposites, hydrogels, or bioinks, remains a challenge, as they must achieve coherent injectability while maintaining shape retention and competent mechanical properties after crosslinking and mineralization. Another challenge is managing the bioactive agents within the material system and their life cycle, which, as previously mentioned, still requires further research.

These challenges are driving the calibration–feedback–optimization loop in the search for various biomanufacturing technologies to realize these bioactive biomaterial systems. Between 3D bioprinting, casting, and mixing, these two methods introduce several parameters to better control the desired outcome. For example, the author is currently experimenting with bioplastic–myco-receptive lattice membranes (Figure 4 and Figure 5) to explore the possible adaptation of bioplastic in the biodigital micro-cellular Mashrabiya design as an architectural system. This system differs from the myco-biocomposite biodigital Mashrabiya in its unlimited and defined receptivity to the microbial strains that can grow on it, with these strains being highly localized to the specific installation site of the biodigital bioplastic Mashrabiya.

Functioning as both an environmental mirror and marker, it reflects the microbiome of a particular zone and location, while also raising health considerations regarding the safety of these strains to users. Therefore, the author is experimenting with media customization of the developed bioplastic material, creating a medium that supports the growth of beneficial microbial strains while inhibiting others.

The other key focus of this project is the form logic of the system, aiming to create a lattice stand-alone structure, which is challenging due to the fragility of the bioplastic membrane. These two aspects, in addition to the study of the hosted microbial cultures (fungi and bacteria), their morphology, physio-chemical interactions with the bioplastic material, and the subsequent effects on the material′s physio-chemical and mechanical properties, represent another current research trajectory. This will be explored further and published in a future study.

Although bioplastic has been shown to be unsuitable for application in lattice Mashrabiya systems due to its poor mechanical properties, which hinder its potential as a standalone material—especially in lattice configurations—it still holds considerable potential for use in the biodigital Mashrabiya system, provided it is combined with other mechanical and antimicrobial enhancers. For instance, the addition of calcium carbonate can improve the mechanical properties of bioplastic [35], while zinc oxide (ZnO) can be incorporated to enhance its antimicrobial properties [36]. This opens further possibilities for applying bioplastic in the design and biofabrication of a biodigital Mashrabiya.

4. Conclusions

The current work aims to propose a 21st-century biodigital Mashrabiya by analyzing previous research on biomaterials, with the goal of integrating them into the built environment to achieve sustainability. Using an analytical-descriptive methodology, the typical characteristics of the traditional Mashrabiya were analyzed to understand its integral sustainability, which can be summarized in seven key points: lightweight, light and air modulation, camouflaging the interior of a building, responsible use of available materials, reproducibility, ease of maintenance, and autonomous operation. In this study, the traditional Mashrabiya was reanalyzed to emphasize its origins and the correct understanding of its philosophy of integral sustainability and environmental architecture efficiency. These criteria were then used to evaluate the feasible application of two developed biomaterials designed and previously published by the author: the 3D-printed myco-biocomposite Mashrabiya and the 3D-bioprinted bone-inspired Mashrabiya. The goal is to offer a biodigital Mashrabiya that is a product of its time, leveraging advances in functional material research and 3D-bioprinting technology. The results revealed that the material scale level is a promising research field for synthesizing customized, bioactive, multi-scale functional materials that can meet the seven key criteria of a typical Mashrabiya in a sustainable and fractal manner. These materials also offer additional benefits, such as mineralization, chronic solidification, cell viability through encapsulation, and the generation of light, oxygen, food, and industrially valuable enzymes. However, in the current stage of research, these two projects still face limitations in terms of mechanical coherency and antimicrobial properties. Nevertheless, they hold considerable potential that warrants further experimentation on their scaling-up and integration into the built environment, as they offer greater sustainability. This opens up further research trajectories focused on customizing 3D bioprinters and printing within the medium space, as well as exploring the life cycle, physicochemical pathways, and environmental interactions of bioactive functional materials, along with their health implications.