Table 1.

Summary of features of miniature fluorescence imaging systems

Systems	Miniature single-photon microscopy			Miniature two-photon microscopy
	Integrated miniature headpiece	Fiber-bundle	Miniature confocal system	Fiber-scanning headpiece	MEMS-scanning headpiece	Fiber-bundle
Weight and size	1.9 g, ~2.4 cm3 [22] 33 g [23] 9 g, 5 cm3 [24] 10 g, 3 cm long [44]	1.1 g [20]	Not reported [28]	25 g, 7.5 cm long [10] 5.5 g [11] 0.6 g [12]	2.9 g, 2.0 × 1.9 × 1.1 cm3 [13] 2.15 g, ~1 cm3 [14]	2.5 g [15]
Signal-to-background contrast	Poor		Good	Excellent
Resolution of neuronal structures	Dendrites and somas resolved with computational processing of sparse activity against background		Cellular resolution	Cellular resolution	Cellular resolution [13] Subcellular resolution that resolves spines [14]	Cellular resolution
Temporal resolution	36 Hz (640×480 pixels) [22] 30 Hz (758×480 pixels) [23] 15 Hz (640×640 pixels) [24] 900 Hz (32×32 pixels) [44]	500 Hz [18] 100 Hz [19] 100 Hz [20]	200 Hz [28]	2 Hz (128×128 pixels) [10] 11 Hz (64×64 pixels) [11] 25 Hz (128×128 pixels) [12]	4 Hz (400 × 135 pixels) [13] 40 Hz (256 × 256 pixels) Line scanning: 10,000 Hz Random-access scanning: 128 Hz (4 neurons) [14]	2.5 Hz [15]
kHz-frame-rate imaging	Yes [44]	Yes [18]	Not reported	Not reported	Not reported	Not reported
FOV	0.5 mm2 [22] 7.8 × 4 mm2 [23] 3 × 3 mm2 [24] 4.8 mm2 [44]	3 × 3 mm2 [18] 685 μm dia. [19] 370 μm dia. [20]	230 μm dia. [28]	65 × 65 μm2 [10] ~250 × 250 μm2 * [11] 200 μm dia. [12]	295 × 100 μm2 [13] 130 × 130 μm2 [14] 420 × 420 μm2 (unpublished) [45]	240 μm dia. [15]
Depth of penetration	50–100 μm		120 μm [28]	250 μm [10]	~150 μm [14] 400 μm (unpublished)	180 μm [15]
Volumetric imaging	Yes [26] (miniature light-field microscopy)	Not reported	Not reported	Not reported	Yes [46]	Yes [15]
Wireless	Yes [27]	Not feasible
Single-neuron precision optogenetics	Not feasible			Feasible

*Derived from figures in the paper.