Page 12 - Science Focus (Issue 017)

Figure 1. 圖一 [2] Figure 2. 圖二 [2]

There are undoubtedly many quirky applications, 根據你的知識，有多少個金屬元素在室溫是呈液
bordering on sci-fi, for this programmable liquid 態的？答案當然是一個，就是汞（Hg；俗稱水銀），因為它
matter in the fields of robotics, medicine and
military. In terms of robotics, it may be possible to 的熔點只有 –38.8 攝氏度。 除了汞之外，科學家也一直嘗
manufacture more flexible robotic components, 試透過結合兩種或更多種金屬，製造在室溫下呈液態的合
which will allow for greater reach and the ability 金。更奇妙的是，近年科學家製造了一些可以按指令變成
to squeeze through tight spaces that conventional 特定形狀的合金。這個研究範疇被稱為「可編程液態物質
robotics are incapable of achieving [3]. Likewise,
programmable liquid matters may have useful （programmable liquid matter）」，雖然這方面的技
applications as a nano-drug carrier or as a 術還沒完全成熟，但距今發展已經令人興奮不已。
minimally invasive surgery tool. On the military
side, it’s possible that programmable liquid matter 可編程液態物質是從「編程物質（programmable
can create self-repairing metal armor for military
vehicles to increase their durability. matter）」的概念而來。後者在 1991 年被首次提出 [1]，
顧名思義，是指一種可以根據用家指示改變其物理性質的
However, there are still many limitations to
the current form of this technology. One major 材料。這些改變是由一些對其「輸入」的指令而引發的，可
obstacle lies in the pre-treatment phase to create 以是從四周的環境來的，或是從用家而來的。因為改變其
the programmable liquid matter in question as it 物理性質的過程就像讓物質執行一個「電腦程式」，因此
requires large amounts of alkaline electrolytes, a 被形容為「可編程（programmable）」。作為可編程液
highly corrosive substance, for even a tiny droplet of
programmable liquid matter. As a result, it is hardly 態物質，這種液態金屬除了會被操控而變成不同固定的形
cost-effective in its production. Another limitation 狀，有時甚至可以改造其他物理性質，例如導電率和表面
is the difficulty to manipulate the liquid metal 張力。一組來自薩塞克斯大學（University of Sussex）
outside of a lab setting as the technology relies on 和史雲斯大學（Swansea University）的科學家就研發了
an electric field and is easily disrupted outside of a
controlled environment. 一種可以隨著電場方向變形的合金 [2]。

This is the story of programmable liquid matter:
a new, previously unimaginable class of materials 在讓合金變形之前，研究人員需要進行很多準備工作。
that can literally bend to your will thanks to electric 首先，他們製造了一種由鎵（Ga）和銦（In）組成、擁有低
fields. While the technology is still in its infancy, we’ll 熔點的共晶 合金，它看來就像水銀一樣的。為了讓這種液
１
hopefully see these programmable liquid matters in 態金屬能扭動和流動成不同形狀，它要先經過強鹼性氫氧
action for some revolutionary robotic components
-
and in various other applications. 化鈉（NaOH）溶液的處理。氫氧離子（OH ）的作用是令
液態金屬表面產生負電荷，因為它會與鎵起化學反應而產
1 Eutectic system: A mixture of substances, in a specific 生陰性的四羥基合鎵酸根離子（Ga(OH)4 ）。同時，溶液
-
proportion, that contains a lower melting point when
compared with its constituent substances’ melting points 中的鈉離子（Na ）會被帶負極性的合金團吸引，使合金團
+
or any mixtures of different proportions [4]. This allows
the gallium-indium alloy to assume a liquid state at room 被均勻的正電荷包圍（圖一 ） 。 在達致平衡的狀態下，合
temperature even though its constituent gallium and indium
metals are solids at room temperature. 金團會呈現其最穩定的形狀 — 完全對稱的球體。