  As a potential revolutionary topic in future information processing,
mechanical computing has gained tremendous attention for replacing or
supplementing conventional electronics vulnerable to power outages, security
attacks, and harsh environments. Despite its potential for constructing
intelligent matter towards nonclassical computing systems beyond the von
Neumann architecture, most works on mechanical computing demonstrated that the
ad hoc design of simple logic gates cannot fully realize a universal mechanical
processing framework involving interconnected arithmetic logic components and
memory. However, such a logic-with-memory computing architecture is critical
for complex and persistent state-dependent computations such as sequential
logic. Here we propose a mechanical transistor (M-Transistor), abstracting
omnipresent temperatures as the input-output mechanical bits, which consists of
a metamaterial thermal channel as the gate terminal driving a nonlinear
bistable soft actuator to selectively connect the output terminal to two other
variable thermal sources. This M-Transistor is an elementary unit to modularly
form various combinational and sequential circuits, such as complex logic
gates, registers (volatile memory), and long-term memories (non-volatile
memory) with much fewer units than the electronic counterparts. Moreover, they
can establish a universal processing core comprising an arithmetic circuit and
a register in a compact, reprogrammable network involving periodic read, write,
memory, and logic operations of the mechanical bits. Our work contributes to
realizing a non-electric universal mechanical computing architecture that
combines multidisciplinary engineering with structural mechanics, materials
science, thermal engineering, physical intelligence, and computational science.
