Table 1.

A usage comparison of floating droplets and static droplets approaches.

	Floating droplets	Static droplets
		SlipChip	MSP	kChip	Programmable microfluidic reaction array
Sample types (Anaerobic cultures are marked by *)	Bacterial pure culture. Environmental microbiota sampled from soil and pond water. Human microbiota sampled from oral, gastrointestinal tract*, and feces*. Animal microbiota sampled from bear oral.	Bacterial pure culture*. Environmental microbiota sampled from soil. Human microbiota sampled from gastrointestinal tract*.	Bacterial pure culture. Environmental microbiota sampled from soil and deep sea sediment. Animal microbiota sampled termite gastrointestinal tract*.	Bacterial pure culture. Environmental microbiota sampled from soil.	Bacterial pure culture. Environmental microbiota sampled from marine enrichment culture, deep sea sediment. Human microbiota sampled from oral.
Typical workflow	Droplet encapsulation. On/Off-chip incubation. Addition of bacterial cells or functional compounds. Growth detection and on/off-chip droplet sorting. Demulsification of droplets to release bacterial cells. Off chip expanded cultivation and isolation. Taxonomy classification by sequencing. Metabolites analysis by using LC–MS.	Loading of reagents and bacterial cells. Manipulation of the liquid in droplets by sliding the chip. Culture and on chip PCR. Off chip expanded cultivation and isolation. Taxonomy classification by sequencing.	Droplet encapsulation. Manual or automatic streaking droplets on Petri dish. Culture. Manual or semi-automatic droplets collection. Expanded cultivation. Taxonomy classification by sequencing.	Encapsulation of microbial cells in color-coded droplets. Pool droplets and load into kChip to form groups. Merge droplet to generate parallel synthetic communities. Tracking the communities’ phenotypes via optical assays.	Droplet encapsulation and loading into a separate storage chamber. On chip incubation and imaging. On chip PCR and WGA. Sample recovery and off-chip sequencing.
Applications	New taxa discovery and isolation. Study of cell–cell interactions. Screening for antibiotic-resistant species. Mining of microbiome resources.	Chemotaxis-based cell sorting. Genetically targeted isolation of interested taxa.	Antimicrobial susceptibility testing. Recovering rare microbial taxa from various environments.	Construction and screening of microbial communities.	Microbes cultivation. Taxonomy classification.

Anaerobic cultures are marked by *, which means that the droplet microdevice was manipulated under anaerobic environment.