# Image Storage in DNA by an Extensible Quaternary Codec System
## 1 Introduction  
With the rapid development of the information age, the total amount of data used globally is projected to grow from 30 ZB in 2018 to 163 ZB by 2025. Based on this trend, researchers predict that by 2040, more than 1000 kg of wafer-scale monocrystalline silicon will be needed to store global data, but only 108 kg of monocrystalline wafers will be available [1]. This impending silicon deficit poses significant challenges to the $574 billion global semiconductor manufacturing sector, where monocrystalline silicon serves as the foundational material for 92% of computing components including CPUs, memory chips, and storage devices [2]. Current projections indicate that maintaining silicon-based storage infrastructure at 2025 data volumes would consume over 65% of annual monocrystalline silicon production, compared to just 22% in 2018 [3]. This resource competition may lead to substantial increases in semiconductor prices, potentially driving significant cost escalation in global computing device production. According to Gartner, Inc.'s latest forecast, worldwide IT spending is projected to reach $5.74 trillion by 2025, with server sales expected to demonstrate exponential growth [4]. DNA-based data storage technology offers a promising solution to this dual crisis of material scarcity and economic pressure. DNA (deoxyribonucleic acid) is a long-strand molecule formed by the connection of fourdeoxyribonucleotideides bases (A, T, C, and G). It ensures the secure storage and stable intergenerational replication of massive quantities of genetic information in living organisms, making it one of the most dense and stable data storage media known. Theoretically, 1 g of DNA can store 455 EB of data, 4 g of DNA can store the total amount of information generated globally in one year, and 1 kg of DNA can store all human information [5]. While DNA exhibits remarkable longevity under controlled conditions (e.g., millennia-old fossils preserve intact sequences [6]), its stability in storage systems requires careful mitigation of enzymatic degradation risks. Environmental DNAses and endonucleases pose significant challenges to unprotected DNA, potentially cleaving phosphodiester bonds and compromising data integrity. To address this, current preservation strategies employ multi-layered protection, such as silica encapsulation and cryogenic storage [7]. Since the dawn of the 21 st century, the field of DNA-based data storage research has witnessed remarkable advancements, fueled by breakthroughs in synthetic biology and collaborative efforts across academia and industry involving researchers, institutions, and enterprises. [PERSON] et al. [8] designed a binary encoding and decoding scheme where one nucleotide corresponded to one binary digit, successfully storing 650 KB of data in vitro. [PERSON] et al. [9] developed a ternary encoding scheme with rotational coding and implemented error correction through quadruple overlapping steps. [PERSON] et al. [10] introduced fountain codes into DNA information storage, using an encoding method where one nucleotide corresponded to two binary digits, marking the advent of the so-called \"quaternary\" codec system. Subsequent studies, including those by [PERSON] et al. [11], [PERSON] et al. [12], [PERSON] et al. [13], [PERSON] et al. [14], [PERSON] et al. [15], [PERSON] et al. [16], and [PERSON] et al. [17], have adopted the innovative concept of fountain codes (as shown in Figure 1). Critically, these encoding paradigms synergize with emerging DNA nanotechnology. By programmatically controlling the spatial arrangement of deoxyribonucleotide bases (A, T, C, and G), DNA strands can serve as programmable building blocks to construct three-dimensional nanostructures through scaffolded origami techniques [18]. This molecular self-assembly process enables the creation of addressable 3D architectures with functionalized domains, effectively integrating data storage with nanoscale structural engineering [19].