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Yang et al. Soft Sci 2024;4:9 https://dx.doi.org/10.20517/ss.2023.43 Page 7 of 26

Table 1. Examples of LMs incorporated with micro-/nano-particles
Liquid metal Doped Approach (reagent) Doping content Improved properties Ref.
composition particles (wt%)
GaIn Ni MPs Mechanical 3%-9% Adhesion [49]
24.5
stirring
GaIn Cu MPs Voltage facilitation 5%-17% Thermal, electrical conductivity & [51]
24.5
(NaOH ) shapeability
aq
GaIn Cu NPs Mechanical stirring 5%-20% Viscosity [52]
24.5
GaIn 24.5 Cu MPs Voltage facilitation 29% Thermal conductivity & shapeability [53]
(NaOH )
aq
GaIn 24.5 Pt-CNTs Mechanical stirring; NMP 3%-15% Thermal and electrical conductivity [54]
GaIn 24.5 Quartz MPs Mechanical stirring or ball UTD Printability and recoverability [55]
milling
GaIn 24.5 Mg MPs Mechanical stirring 0.5%-3% PT conversion efficiency and [56]
shapeability
GaIn 24.5 Fe NPs HCl aq UTD Magnetization [57]
Ga In Sn Fe MPs HCl 2%-20% Elongation [58]
67 20.5 12.5 aq
Ga 68.5 In 21.5 Sn 10 W MPs Oxide wetting 10%-90% Enhanced thermal conductivity [59]
GaIn Fe NPs + Self-assembly of MXene UTD Shape deformability and locomotion [60]
24.5
MXene
CNTs: Carbon nanotubes; LMs: liquid metals; MPs: micro-particles; NMP: N-Methyl-2-pyrrolidone; NPs: nano-particles; PT: photothermal; UTD:
unable to determine.

surfactants and obtained LM nanospheres. Then, they heated the sample at 70 °C for 30 min, and the
nanospheres transformed into nanorods. They further manifested that such a morphology shift was due to
[62]
the production of gallium hydroxide (GaOOH) . Gan et al. prepared polydopamine-coated LMNPs and
took advantage of the PT conversion capability of polydopamine to heat inner LMs, triggering shape
morphing of LMNPs from spheres to ellipsoids . Li et al. performed sonication with relatively high power
[48]
(800 W) and extended duration (120 min) to maximize oxidization and obtained LM nanorods . Sun et al.
[63]
sonicated LMs in an aqueous solution containing cetrimonium bromide, a positively charged surfactant, to
obtain gallium and EGaIn nanorods . In addition to sonication methods, due to the liquid nature of
[40]
gallium, Wang et al. adopted a pressure-derived filtering approach to fabricating homogeneous gallium
[64]
nanorods at 35 °C . As reported by Sun et al., different morphologies of LMNPs will result in varying
thermal properties (e.g., thermal conductivity due to the composition change, specific absorption rate, PT
[40]
efficiency, etc.) and biodegradability .

Sun et al. reported an intriguing transformation behavior of LMMPs under a space-restricted two-phase
[65]
condition . When the LMMPs were cooled in a solution with a higher melting point, the basal solution
would first solidify and trap the LMMPs. Then, as the temperature continued to decrease, the LMMPs
would expand due to the abnormal volume expansion phenomenon and explode to form spikes to pierce
the surrounding ice. This phenomenon offered a distinct inspiration to exert excess mechanical damage to
tumor tissues in cryosurgery [Figure 2C].

THERMAL PROPERTIES OF LM
With the development of cryobiological techniques, precise and rapid temperature control is essential to
achieve optimistic outcomes. However, it is hindered by the intrinsic low thermal conductivity of
biomaterials . Inferior heat transfer results in failures in both cryoablation and cryopreservation, e.g.,
[66]
insufficient elimination of cancer cells, damage to healthy tissues, ice recrystallization during thawing of the
vitrified biosamples, etc. To tackle this challenge, scientists have added adjuvants to improve the heat
transfer and homogenize heat distribution. Ideally, nanomaterials with self-heating effects (e.g., GNRs,